Subject: [NEXTEL-1] The Electromagnetic Bomb - a Weapon of Electrical Mass Destruction

From: Marcel <[email-masked]>
Date: Tue, 10 Dec 2002 14:06:46 -0500

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The Electromagnetic Bomb - a Weapon of Electrical Mass Destruction

Carlo Kopp

Defence Analyst

Melbourne, Australia

[email-masked]

http://www.cs.monash.edu.au/~carlo/

ABSTRACT

High Power Electromagnetic Pulse generation techniques and High Power
Microwave technology have matured to the point where practical E-bombs (Electromagnetic
bombs) are becoming technically feasible, with new applications in both Strategic and
Tactical Information Warfare. The development of conventional E-bomb devices allows their
use in non-nuclear confrontations. This paper discusses aspects of the technology base,
weapon delivery techniques and proposes a doctrinal foundation for the use of such devices
in warhead and bomb applications.

1. Introduction

The prosecution of a successful Information Warfare (IW) campaign against an
industrialised or post industrial opponent will require a suitable set of tools. As
demonstrated in the Desert Storm air campaign, air power has proven to be a most effective
means of inhibiting the functions of an opponent's vital information processing
infrastructure. This is because air power allows concurrent or parallel engagement of a
large number of targets over geographically significant areas [SZAFRANSKI95].

While Desert Storm demonstrated that the application of air power was the most
practical means of crushing an opponent's information processing and transmission nodes,
the need to physically destroy these with guided munitions absorbed a substantial
proportion of available air assets in the early phase of the air campaign. Indeed, the
aircraft capable of delivery laser guided bombs were largely occupied with this very
target set during the first nights of the air battle.

The efficient execution of an IW campaign against a modern industrial or
post-industrial opponent will require the use of specialised tools designed to destroy
information systems. Electromagnetic bombs built for this purpose can provide, where
delivered by suitable means, a very effective tool for this purpose.

2.The EMP Effect

The ElectroMagnetic Pulse (EMP) effect [1] was first
observed during the early testing of high altitude airburst nuclear weapons [GLASSTONE64].
The effect is characterised by the production of a very short (hundreds of nanoseconds)
but intense electromagnetic pulse, which propagates away from its source with ever
diminishing intensity, governed by the theory of electromagnetism. The ElectroMagnetic
Pulse is in effect an electromagnetic shock wave.

This pulse of energy produces a powerful electromagnetic field, particularly within the
vicinity of the weapon burst. The field can be sufficiently strong to produce short lived
transient voltages of thousands of Volts (ie kiloVolts) on exposed electrical conductors,
such as wires, or conductive tracks on printed circuit boards, where exposed.

It is this aspect of the EMP effect which is of military significance, as it can result
in irreversible damage to a wide range of electrical and electronic equipment,
particularly computers and radio or radar receivers. Subject to the electromagnetic
hardness of the electronics, a measure of the equipment's resilience to this effect, and
the intensity of the field produced by the weapon, the equipment can be irreversibly
damaged or in effect electrically destroyed. The damage inflicted is not unlike that
experienced through exposure to close proximity lightning strikes, and may require
complete replacement of the equipment, or at least substantial portions thereof.

Commercial computer equipment is particularly vulnerable to EMP effects, as it is
largely built up of high density Metal Oxide Semiconductor (MOS) devices, which are very
sensitive to exposure to high voltage transients. What is significant about MOS devices is
that very little energy is required to permanently wound or destroy them, any voltage in
typically in excess of tens of Volts can produce an effect termed gate breakdown which
effectively destroys the device. Even if the pulse is not powerful enough to produce
thermal damage, the power supply in the equipment will readily supply enough energy to
complete the destructive process. Wounded devices may still function, but their
reliability will be seriously impaired. Shielding electronics by equipment chassis
provides only limited protection, as any cables running in and out of the equipment will
behave very much like antennae, in effect guiding the high voltage transients into the
equipment.

Computers used in data processing systems, communications systems, displays, industrial
control applications, including road and rail signalling, and those embedded in military
equipment, such as signal processors, electronic flight controls and digital engine
control systems, are all potentially vulnerable to the EMP effect.

Other electronic devices and electrical equipment may also be destroyed by the EMP
effect. Telecommunications equipment can be highly vulnerable, due to the presence of
lengthy copper cables between devices. Receivers of all varieties are particularly
sensitive to EMP, as the highly sensitive miniature high frequency transistors and diodes
in such equipment are easily destroyed by exposure to high voltage electrical transients.
Therefore radar and electronic warfare equipment, satellite, microwave, UHF, VHF, HF and
low band communications equipment and television equipment are all potentially vulnerable
to the EMP effect.

It is significant that modern military platforms are densely packed with electronic
equipment, and unless these platforms are well hardened, an EMP device can substantially
reduce their function or render them unusable.

3. The Technology Base for Conventional Electromagnetic Bombs

The technology base which may be applied to the design of electromagnetic bombs is both
diverse, and in many areas quite mature. Key technologies which are extant in the area are
explosively pumped Flux Compression Generators (FCG), explosive or propellant driven
Magneto-Hydrodynamic (MHD) generators and a range of HPM devices, the foremost of which is
the Virtual Cathode Oscillator or Vircator. A wide range of experimental designs have been
tested in these technology areas, and a considerable volume of work has been published in
unclassified literature.

This paper will review the basic principles and attributes of these technologies, in
relation to bomb and warhead applications. It is stressed that this treatment is not
exhaustive, and is only intended to illustrate how the technology base can be adapted to
an operationally deployable capability.

3.1. Explosively Pumped Flux Compression Generators

The explosively pumped FCG is the most mature technology applicable to bomb designs.
The FCG was first demonstrated by Clarence Fowler at Los Alamos National Laboratories
(LANL) in the late fifties [FOWLER60]. Since that time a wide range of FCG configurations
has been built and tested, both in the US and the USSR, and more recently CIS.

The FCG is a device capable of producing electrical energies of tens of MegaJoules in
tens to hundreds of microseconds of time, in a relatively compact package. With peak power
levels of the order of TeraWatts to tens of TeraWatts, FCGs may be used directly, or as
one shot pulse power supplies for microwave tubes. To place this in perspective, the
current produced by a large FCG is between ten to a thousand times greater than that
produced by a typical lightning stroke [WHITE78].

The central idea behind the construction of FCGs is that of using a fast explosive to
rapidly compress a magnetic field, transferring much energy from the explosive into the
magnetic field.

The initial magnetic field in the FCG prior to explosive initiation is produced by a
start current. The start current is supplied by an external source, such a a high voltage
capacitor bank (Marx bank), a smaller FCG or an MHD device. In principle, any device
capable of producing a pulse of electrical current of the order of tens of kiloAmperes to
MegaAmperes will be suitable.

A number of geometrical configurations for FCGs have been published (for examples see
REINOVSKY85, CAIRD85, FOWLER89) The most commonly used arrangement is that of the coaxial
FCG. The coaxial arrangement is of particular interest in this context, as its essentially
cylindrical form factor lends itself to packaging into munitions.

In a typical coaxial FCG , a cylindrical copper tube forms the armature. This tube is
filled with a fast high energy explosive. A number of explosive types have been used,
ranging from B and C-type compositions to machined blocks of PBX-9501. The armature is
surrounded by a helical coil of heavy wire, typically copper, which forms the FCG stator.
The stator winding is in some designs split into segments, with wires bifurcating at the
boundaries of the segments, to optimise the electromagnetic inductance of the armature
coil.

The intense magnetic forces produced during the operation of the FCG could potentially
cause the device to disintegrate prematurely if not dealt with. This is typically
accomplished by the addition of a structural jacket of a non-magnetic material. Materials
such as concrete or Fibreglass in an Epoxy matrix have been used. In principle, any
material with suitable electrical and mechanical properties could be used. In applications
where weight is an issue, such as air delivered bombs or missile warheads, a glass or
Kevlar Epoxy composite would be a viable candidate.

It is typical that the explosive is initiated when the start current peaks. This is
usually accomplished with a explosive lense plane wave generator which produces a uniform
plane wave burn (or detonation) front in the explosive. Once initiated, the front
propagates through the explosive in the armature, distorting it into a conical shape
(typically 12 to 14 degrees of arc). Where the armature has expanded to the full diameter
of the stator, it forms a short circuit between the ends of the stator coil, shorting and
thus isolating the start current source and trapping the current within the device. The
propagating short has the effect of compressing the magnetic field, whilst reducing the
inductance of the stator winding. The result is that such generators will producing a
ramping current pulse, which peaks before the final disintegration of the device.
Published results suggest ramp times of tens to hundreds of microseconds, specific to the
characteristics of the device, for peak currents of tens of MegaAmperes and peak energies
of tens of MegaJoules.

The current multiplication (ie ratio of output current to start current) achieved
varies with designs, but numbers as high as 60 have been demonstrated. In a munition
application, where space and weight are at a premium, the smallest possible start current
source is desirable. These applications can exploit cascading of FCGs, where a small FCG
is used to prime a larger FCG with a start current. Experiments conducted by LANL and AFWL
have demonstrated the viability of this technique [KIRTLAND94, REINOVSKY85].

The principal technical issues in adapting the FCG to weapons applications lie in
packaging, the supply of start current, and matching the device to the intended load.
Interfacing to a load is simplified by the coaxial geometry of coaxial and conical FCG
designs. Significantly, this geometry is convenient for weapons applications, where FCGs
may be stacked axially with devices such a microwave Vircators. The demands of a load such
as a Vircator, in terms of waveform shape and timing, can be satisfied by inserting pulse
shaping networks, transformers and explosive high current switches.

3.2. Explosive and Propellant Driven MHD Generators

The design of explosive and propellant driven Magneto-Hydrodynamic generators is a much
less mature art that that of FCG design. Technical issues such as the size and weight of
magnetic field generating devices required for the operation of MHD generators suggest
that MHD devices will play a minor role in the near term. In the context of this paper,
their potential lies in areas such as start current generation for FCG devices.

The fundamental principle behind the design of MHD devices is that a conductor moving
through a magnetic field will produce an electrical current transverse to the direction of
the field and the conductor motion. In an explosive or propellant driven MHD device, the
conductor is a plasma of ionised explosive or propellant gas, which travels through the
magnetic field. Current is collected by electrodes which are in contact with the plasma
jet [FANTHOME89].

The electrical properties of the plasma are optimised by seeding the explosive or
propellant with with suitable additives, which ionise during the burn [FANTHOME89,
FLANAGAN81]. Published experiments suggest that a typical arrangement uses a solid
propellant gas generator, often using conventional ammunition propellant as a base.
Cartridges of such propellant can be loaded much like artillery rounds, for multiple shot
operation.

3.3. High Power Microwave Sources - The Vircator

Whilst FCGs are potent technology base for the generation of large electrical power
pulses, the output of the FCG is by its basic physics constrained to the frequency band
below 1 MHz. Many target sets will be difficult to attack even with very high power levels
at such frequencies, moreover focussing the energy output from such a device will be
problematic. A HPM device overcomes both of the problems, as its output power may be
tightly focussed and it has a much better ability to couple energy into many target types.

A wide range of HPM devices exist. Relativistic Klystrons, Magnetrons, Slow Wave
Devices, Reflex triodes, Spark Gap Devices and Vircators are all examples of the available
technology base [GRANATSTEIN87, HOEBERLING92]. From the perspective of a bomb or warhead
designer, the device of choice will be at this time the Vircator, or in the nearer term a
Spark Gap source. The Vircator is of interest because it is a one shot device capable of
producing a very powerful single pulse of radiation, yet it is mechanically simple, small
and robust, and can operate over a relatively broad band of microwave frequencies.

The physics of the Vircator tube are substantially more complex than those of the
preceding devices. The fundamental idea behind the Vircator is that of accelerating a high
current electron beam against a mesh (or foil) anode. Many electrons will pass through the
anode, forming a bubble of space charge behind the anode. Under the proper conditions,
this space charge region will oscillate at microwave frequencies. If the space charge
region is placed into a resonant cavity which is appropriately tuned, very high peak
powers may be achieved. Conventional microwave engineering techniques may then be used to
extract microwave power from the resonant cavity. Because the frequency of oscillation is
dependent upon the electron beam parameters, Vircators may be tuned or chirped in
frequency, where the microwave cavity will support appropriate modes. Power levels
achieved in Vircator experiments range from 170 kiloWatts to 40 GigaWatts over frequencies
spanning the decimetric and centimetric bands [THODE87].

The two most commonly described configurations for the Vircator are the Axial Vircator
(AV) (Fig.3), and the Transverse Vircator (TV). The Axial Vircator is the simplest by
design, and has generally produced the best power output in experiments. It is typically
built into a cylindrical waveguide structure. Power is most often extracted by
transitioning the waveguide into a conical horn structure, which functions as an antenna.
AVs typically oscillate in Transverse Magnetic (TM) modes. The Transverse Vircator injects
cathode current from the side of the cavity and will typically oscillate in a Transverse
Electric (TE) mode.

Technical issues in Vircator design are output pulse duration, which is typically of
the order of a microsecond and is limited by anode melting, stability of oscillation
frequency, often compromised by cavity mode hopping, conversion efficiency and total power
output. Coupling power efficiently from the Vircator cavity in modes suitable for a chosen
antenna type may also be an issue, given the high power levels involved and thus the
potential for electrical breakdown in insulators.

4. The Lethality of Electromagnetic Warheads

The issue of electromagnetic weapon lethality is complex. Unlike the technology base
for weapon construction, which has been widely published in the open literature, lethality
related issues have been published much less frequently.

While the calculation of electromagnetic field strengths achievable at a given radius
for a given device design is a straightforward task, determining a kill probability for a
given class of target under such conditions is not.

This is for good reasons. The first is that target types are very diverse in their
electromagnetic hardness, or ability to resist damage. Equipment which has been
intentionally shielded and hardened against electromagnetic attack will withstand orders
of magnitude greater field strengths than standard commercially rated equipment. Moreover,
various manufacturer's implementations of like types of equipment may vary significantly
in hardness due the idiosyncrasies of specific electrical designs, cabling schemes and
chassis/shielding designs used.

The second major problem area in determining lethality is that of coupling efficiency,
which is a measure of how much power is transferred from the field produced by the weapon
into the target. Only power coupled into the target can cause useful damage.

4.1. Coupling Modes

In assessing how power is coupled into targets, two principal coupling modes are
recognised in the literature:

Front Door Coupling occurs typically when power from a electromagnetic weapon is coupled
into an antenna associated with radar or communications equipment. The antenna subsystem
is designed to couple power in and out of the equipment, and thus provides an efficient
path for the power flow from the electromagnetic weapon to enter the equipment and cause
damage.

Back Door Coupling occurs when the electromagnetic field from a weapon produces large
transient currents (termed spikes, when produced by a low frequency weapon ) or electrical
standing waves (when produced by a HPM weapon) on fixed electrical wiring and cables
interconnecting equipment, or providing connections to mains power or the telephone
network [TAYLOR92, WHITE78]. Equipment connected to exposed cables or wiring will
experience either high voltage transient spikes or standing waves which can damage power
supplies and communications interfaces if these are not hardened. Moreover, should the
transient penetrate into the equipment, damage can be done to other devices inside.

A low frequency weapon will couple well into a typical wiring infrastructure, as most
telephone lines, networking cables and power lines follow streets, building risers and
corridors. In most instances any particular cable run will comprise multiple linear
segments joined at approximately right angles. Whatever the relative orientation of the
weapons field, more than one linear segment of the cable run is likely to be oriented such
that a good coupling efficiency can be achieved.

It is worth noting at this point the safe operating envelopes of some typical types of
semiconductor devices. Manufacturer's guaranteed breakdown voltage ratings for Silicon
high frequency bipolar transistors, widely used in communications equipment, typically
vary between 15 V and 65 V. Gallium Arsenide Field Effect Transistors are usually rated at
about 10V. High density Dynamic Random Access Memories (DRAM), an essential part of any
computer, are usually rated to 7 V against earth. Generic CMOS logic is rated between 7 V
and 15 V, and microprocessors running off 3.3 V or 5 V power supplies are usually rated
very closely to that voltage. Whilst many modern devices are equipped with additional
protection circuits at each pin, to sink electrostatic discharges, sustained or repeated
application of a high voltage will often defeat these [MOTO3, MICRON92, NATSEMI86].

Communications interfaces and power supplies must typically meet electrical safety
requirements imposed by regulators. Such interfaces are usually protected by isolation
transformers with ratings from hundreds of Volts to about 2 to 3 kV [NPI93].

It is clearly evident that once the defence provided by a transformer, cable pulse
arrestor or shielding is breached, voltages even as low as 50 V can inflict substantial
damage upon computer and communications equipment. The author has seen a number of
equipment items (computers, consumer electronics) exposed to low frequency high voltage
spikes (near lightning strikes, electrical power transients), and in every instance the
damage was extensive, often requiring replacement of most semiconductors in the equipment [2].

HPM weapons operating in the centimetric and millimetric bands however offer an
additional coupling mechanism to Back Door Coupling. This is the ability to directly
couple into equipment through ventilation holes, gaps between panels and poorly shielded
interfaces. Under these conditions, any aperture into the equipment behaves much like a
slot in a microwave cavity, allowing microwave radiation to directly excite or enter the
cavity. The microwave radiation will form a spatial standing wave pattern within the
equipment. Components situated within the anti-nodes within the standing wave pattern will
be exposed to potentially high electromagnetic fields.

Because microwave weapons can couple more readily than low frequency weapons, and can
in many instances bypass protection devices designed to stop low frequency coupling,
microwave weapons have the potential to be significantly more lethal than low frequency
weapons.

What research has been done in this area illustrates the difficulty in producing
workable models for predicting equipment vulnerability. It does however provide a solid
basis for shielding strategies and hardening of equipment.

The diversity of likely target types and the unknown geometrical layout and
electrical characteristics of the wiring and cabling infrastructure surrounding a target
makes the exact prediction of lethality impossible.

A general approach for dealing with wiring and cabling related back door coupling is to
determine a known lethal voltage level, and then use this to find the required field
strength to generate this voltage. Once the field strength is known, the lethal radius for
a given weapon configuration can be calculated.

A trivial example is that of a 10 GW 5 GHz HPM device illuminating a footprint of 400
to 500 metres diameter, from a distance of several hundred metres. This will result in
field strengths of several kiloVolts per metre within the device footprint, in turn
capable of producing voltages of hundreds of volts to kiloVolts on exposed wires or cables
[KRAUS88, TAYLOR92]. This suggests lethal radii of the order of hundreds of metres,
subject to weapon performance and target set electrical hardness.

4.2. Maximising Electromagnetic Bomb Lethality

To maximise the lethality of an electromagnetic bomb it is necessary to maximise the
power coupled into the target set.

The first step in maximising bomb lethality is is to maximise the peak power and
duration of the radiation of the weapon. For a given bomb size, this is accomplished by
using the most powerful flux compression generator (and Vircator in a HPM bomb) which will
fit the weapon size, and by maximising the efficiency of internal power transfers in the
weapon. Energy which is not emitted is energy wasted at the expense of lethality.

The second step is to maximise the coupling efficiency into the target set. A good
strategy for dealing with a complex and diverse target set is to exploit every coupling
opportunity available within the bandwidth of the weapon.

A low frequency bomb built around an FCG will require a large antenna to provide good
coupling of power from the weapon into the surrounding environment. Whilst weapons built
this way are inherently wide band, as most of the power produced lies in the frequency
band below 1 MHz compact antennas are not an option. One possible scheme is for a bomb
approaching its programmed firing altitude to deploy five linear antenna elements. These
are produced by firing off cable spools which unwind several hundred metres of cable. Four
radial antenna elements form a "virtual" earth plane around the bomb, while an
axial antenna element is used to radiate the power from the FCG. The choice of element
lengths would need to be carefully matched to the frequency characteristics of the weapon,
to produce the desired field strength. A high power coupling pulse transformer is used to
match the low impedance FCG output to the much higher impedance of the antenna, and ensure
that the current pulse does not vapourise the cable prematurely.

Other alternatives are possible. One is to simply guide the bomb very close to the
target, and rely upon the near field produced by the FCG winding, which is in effect a
loop antenna of very small diameter relative to the wavelength. Whilst coupling efficiency
is inherently poor, the use of a guided bomb would allow the warhead to be positioned
accurately within metres of a target. An area worth further investigation in this context
is the use of low frequency bombs to damage or destroy magnetic tape libraries, as the
near fields in the vicinity of a flux generator are of the order of magnitude of the
coercivity of most modern magnetic materials.

Microwave bombs have a broader range of coupling modes and given the small wavelength
in comparison with bomb dimensions, can be readily focussed against targets with a compact
antenna assembly. Assuming that the antenna provides the required weapon footprint, there
are at least two mechanisms which can be employed to further maximise lethality.

The first is sweeping the frequency or chirping the Vircator. This can improve coupling
efficiency in comparison with a single frequency weapon, by enabling the radiation to
couple into apertures and resonances over a range of frequencies. In this fashion, a
larger number of coupling opportunities are exploited.

The second mechanism which can be exploited to improve coupling is the polarisation of
the weapon's emission. If we assume that the orientations of possible coupling apertures
and resonances in the target set are random in relation to the weapon's antenna
orientation, a linearly polarised emission will only exploit half of the opportunities
available. A circularly polarised emission will exploit all coupling opportunities.

The practical constraint is that it may be difficult to produce an efficient high power
circularly polarised antenna design which is compact and performs over a wide band. Some
work therefore needs to be done on tapered helix or conical spiral type antennas capable
of handling high power levels, and a suitable interface to a Vircator with multiple
extraction ports must devised. A possible implementation is depicted in Fig.5. In this
arrangement, power is coupled from the tube by stubs which directly feed a multi-filar
conical helix antenna. An implementation of this scheme would need to address the specific
requirements of bandwidth, beamwidth, efficiency of coupling from the tube, while
delivering circularly polarised radiation.

Another aspect of electromagnetic bomb lethality is its detonation altitude, and by
varying the detonation altitude, a tradeoff may be achieved between the size of the lethal
footprint and the intensity of the electromagnetic field in that footprint. This provides
the option of sacrificing weapon coverage to achieve kills against targets of greater
electromagnetic hardness, for a given bomb size (Fig.7, 8). This is not unlike the use of
airburst explosive devices.

In summary, lethality is maximised by maximising power output and the efficiency of
energy transfer from the weapon to the target set. Microwave weapons offer the ability to
focus nearly all of their energy output into the lethal footprint, and offer the ability
to exploit a wider range of coupling modes. Therefore, microwave bombs are the preferred
choice.

5. Targeting Electromagnetic Bombs

The task of identifying targets for attack with electromagnetic bombs can be complex.
Certain categories of target will be very easy to identify and engage. Buildings housing
government offices and thus computer equipment, production facilities, military bases and
known radar sites and communications nodes are all targets which can be readily identified
through conventional photographic, satellite, imaging radar, electronic reconnaissance and
humint operations. These targets are typically geographically fixed and thus may be
attacked providing that the aircraft can penetrate to weapon release range. With the
accuracy inherent in GPS/inertially guided weapons, the electromagnetic bomb can be
programmed to detonate at the optimal position to inflict a maximum of electrical damage.

Mobile and camouflaged targets which radiate overtly can also be readily engaged.
Mobile and relocatable air defence equipment, mobile communications nodes and naval
vessels are all good examples of this category of target. While radiating, their positions
can be precisely tracked with suitable Electronic Support Measures (ESM) and Emitter
Locating Systems (ELS) carried either by the launch platform or a remote surveillance
platform. In the latter instance target coordinates can be continuously datalinked to the
launch platform. As most such targets move relatively slowly, they are unlikely to escape
the footprint of the electromagnetic bomb during the weapon's flight time.

Mobile or hidden targets which do not overtly radiate may present a problem,
particularly should conventional means of targeting be employed. A technical solution to
this problem does however exist, for many types of target. This solution is the detection
and tracking of Unintentional Emission (UE) [HERSKOWITZ96]. UE has attracted most
attention in the context of TEMPEST [3] surveillance, where
transient emanations leaking out from equipment due poor shielding can be detected and in
many instances demodulated to recover useful intelligence. Termed Van Eck radiation
[VECK85], such emissions can only be suppressed by rigorous shielding and emission control
techniques, such as are employed in TEMPEST rated equipment.

Whilst the demodulation of UE can be a technically difficult task to perform well, in
the context of targeting electromagnetic bombs this problem does not arise. To target such
an emitter for attack requires only the ability to identify the type of emission and thus
target type, and to isolate its position with sufficient accuracy to deliver the bomb.
Because the emissions from computer monitors, peripherals, processor equipment, switchmode
power supplies, electrical motors, internal combustion engine ignition systems, variable
duty cycle electrical power controllers (thyristor or triac based), superheterodyne
receiver local oscillators and computer networking cables are all distinct in their
frequencies and modulations, a suitable Emitter Locating System can be designed to detect,
identify and track such sources of emission.

A good precedent for this targeting paradigm exists. During the SEA (Vietnam) conflict
the United States Air Force (USAF) operated a number of night interdiction gunships which
used direction finding receivers to track the emissions from vehicle ignition systems.
Once a truck was identified and tracked, the gunship would engage it [4].

Because UE occurs at relatively low power levels, the use of this detection method
prior to the outbreak of hostilities can be difficult, as it may be necessary to overfly
hostile territory to find signals of usable intensity [5]. The
use of stealthy reconnaissance aircraft or long range, stealthy Unmanned Aerial Vehicles
(UAV) may be required. The latter also raises the possibility of autonomous
electromagnetic warhead armed expendable UAVs, fitted with appropriate homing receivers.
These would be programmed to loiter in a target area until a suitable emitter is detected,
upon which the UAV would home in and expend itself against the target.

6. The Delivery of Conventional Electromagnetic Bombs

As with explosive warheads, electromagnetic warheads will occupy a volume of physical
space and will also have some given mass (weight) determined by the density of the
internal hardware. Like explosive warheads, electromagnetic warheads may be fitted to a
range of delivery vehicles.

Known existing applications [6] involve fitting an
electromagnetic warhead to a cruise missile airframe. The choice of a cruise missile
airframe will restrict the weight of the weapon to about 340 kg (750 lb), although some
sacrifice in airframe fuel capacity could see this size increased. A limitation in all
such applications is the need to carry an electrical energy storage device, eg a battery,
to provide the current used to charge the capacitors used to prime the FCG prior to its
discharge. Therefore the available payload capacity will be split between the electrical
storage and the weapon itself.

In wholly autonomous weapons such as cruise missiles, the size of the priming current
source and its battery may well impose important limitations on weapon capability. Air
delivered bombs, which have a flight time between tens of seconds to minutes, could be
built to exploit the launch aircraft's power systems. In such a bomb design, the bomb's
capacitor bank can be charged by the launch aircraft enroute to target, and after release
a much smaller onboard power supply could be used to maintain the charge in the priming
source prior to weapon initiation.

An electromagnetic bomb delivered by a conventional aircraft [7]
can offer a much better ratio of electromagnetic device mass to total bomb mass, as most
of the bomb mass can be dedicated to the electromagnetic device installation itself. It
follows therefore, that for a given technology an electromagnetic bomb of identical mass
to a electromagnetic warhead equipped missile can have a much greater lethality, assuming
equal accuracy of delivery and technologically similar electromagnetic device design.

A missile borne electromagnetic warhead installation will comprise the electromagnetic
device, an electrical energy converter, and an onboard storage device such as a battery.
As the weapon is pumped, the battery is drained. The electromagnetic device will be
detonated by the missile's onboard fusing system. In a cruise missile, this will be tied
to the navigation system; in an anti-shipping missile the radar seeker and in an
air-to-air missile, the proximity fusing system. The warhead fraction (ie ratio of total
payload (warhead) mass to launch mass of the weapon) will be between 15% and 30% [8].

An electromagnetic bomb warhead will comprise an electromagnetic device, an electrical
energy converter and a energy storage device to pump and sustain the electromagnetic
device charge after separation from the delivery platform. Fusing could be provided by a
radar altimeter fuse to airburst the bomb, a barometric fuse or in GPS/inertially guided
bombs, the navigation system. The warhead fraction could be as high as 85%, with most of
the usable mass occupied by the electromagnetic device and its supporting hardware.

Due to the potentially large lethal radius of an electromagnetic device, compared to an
explosive device of similar mass, standoff delivery would be prudent. Whilst this is an
inherent characteristic of weapons such as cruise missiles, potential applications of
these devices to glidebombs, anti-shipping missiles and air-to-air missiles would dictate
fire and forget guidance of the appropriate variety, to allow the launching aircraft to
gain adequate separation of several miles before warhead detonation.

The recent advent of GPS satellite navigation guidance kits for conventional bombs and
glidebombs has provided the optimal means for cheaply delivering such weapons. While GPS
guided weapons without differential GPS enhancements may lack the pinpoint accuracy of
laser or television guided munitions, they are still quite accurate (CEP \(~~ 40 ft) and
importantly, cheap, autonomous all weather weapons.

The USAF has recently deployed the Northrop GAM (GPS Aided Munition) on the B-2 bomber
[NORTHROP95], and will by the end of the decade deploy the GPS/inertially guided GBU-29/30
JDAM (Joint Direct Attack Munition)[MDC95] and the AGM-154 JSOW (Joint Stand Off Weapon)
[PERGLER94] glidebomb. Other countries are also developing this technology, the Australian
BAeA AGW (Agile Glide Weapon) glidebomb achieving a glide range of about 140 km (75 nmi)
when launched from altitude [KOPP96].

The importance of glidebombs as delivery means for HPM warheads is threefold. Firstly,
the glidebomb can be released from outside effective radius of target air defences,
therefore minimising the risk to the launch aircraft. Secondly, the large standoff range
means that the aircraft can remain well clear of the bomb's effects. Finally the bomb's
autopilot may be programmed to shape the terminal trajectory of the weapon, such that a
target may be engaged from the most suitable altitude and aspect.

A major advantage of using electromagnetic bombs is that they may be delivered by any
tactical aircraft with a nav-attack system capable of delivering GPS guided munitions. As
we can expect GPS guided munitions to be become the standard weapon in use by Western air
forces by the end of this decade, every aircraft capable of delivering a standard guided
munition also becomes a potential delivery vehicle for a electromagnetic bomb. Should
weapon ballistic properties be identical to the standard weapon, no software changes to
the aircraft would be required.

Because of the simplicity of electromagnetic bombs in comparison with weapons such as
Anti Radiation Missiles (ARM), it is not unreasonable to expect that these should be both
cheaper to manufacture, and easier to support in the field, thus allowing for more
substantial weapon stocks. In turn this makes saturation attacks a much more viable
proposition.

In this context it is worth noting that the USAF's possesion of the JDAM capable F-117A
and B-2A will provide the capability to deliver E-bombs against arbitrary high value
targets with virtual impunity. The ability of a B-2A to deliver up to sixteen GAM/JDAM
fitted E-bomb warheads with a 20 ft class CEP would allow a small number of such aircraft
to deliver a decisive blow against key strategic, air defence and theatre targets. A
strike and electronic combat capable derivative of the F-22 would also be a viable
delivery platform for an E-bomb/JDAM. With its superb radius, low signature and supersonic
cruise capability an RFB-22 could attack air defence sites, C3I sites, airbases and
strategic targets with E-bombs, achieving a significant shock effect. A good case may be
argued for the whole F-22 build to be JDAM/E-bomb capable, as this would allow the USAF to
apply the maximum concentration of force against arbitrary air and surface targets during
the opening phase of an air campaign.

7. Defence Against Electromagnetic Bombs

The most effective defence against electromagnetic bombs is to prevent their delivery
by destroying the launch platform or delivery vehicle, as is the case with nuclear
weapons. This however may not always be possible, and therefore systems which can be
expected to suffer exposure to the electromagnetic weapons effects must be
electromagnetically hardened.

The most effective method is to wholly contain the equipment in an electrically
conductive enclosure, termed a Faraday cage, which prevents the electromagnetic field from
gaining access to the protected equipment. However, most such equipment must communicate
with and be fed with power from the outside world, and this can provide entry points via
which electrical transients may enter the enclosure and effect damage. While optical
fibres address this requirement for transferring data in and out, electrical power feeds
remain an ongoing vulnerability.

Where an electrically conductive channel must enter the enclosure, electromagnetic
arresting devices must be fitted. A range of devices exist, however care must be taken in
determining their parameters to ensure that they can deal with the rise time and strength
of electrical transients produced by electromagnetic devices. Reports from the US [9] indicate that hardening measures attuned to the behaviour of
nuclear EMP bombs do not perform well when dealing with some conventional microwave
electromagnetic device designs.

It is significant that hardening of systems must be carried out at a system level, as
electromagnetic damage to any single element of a complex system could inhibit the
function of the whole system. Hardening new build equipment and systems will add a
substantial cost burden. Older equipment and systems may be impossible to harden properly
and may require complete replacement. In simple terms, hardening by design is
significantly easier than attempting to harden existing equipment.

An interesting aspect of electrical damage to targets is the possibility of wounding
semiconductor devices thereby causing equipment to suffer repetitive intermittent faults
rather than complete failures. Such faults would tie down considerable maintenance
resources while also diminishing the confidence of the operators in the equipment's
reliability. Intermittent faults may not be possible to repair economically, thereby
causing equipment in this state to be removed from service permanently, with considerable
loss in maintenance hours during damage diagnosis. This factor must also be considered
when assessing the hardness of equipment against electromagnetic attack, as partial or
incomplete hardening may in this fashion cause more difficulties than it would solve.
Indeed, shielding which is incomplete may resonate when excited by radiation and thus
contribute to damage inflicted upon the equipment contained within it.

Other than hardening against attack, facilities which are concealed should not radiate
readily detectable emissions. Where radio frequency communications must be used, low
probability of intercept (ie spread spectrum) techniques should be employed exclusively to
preclude the use of site emissions for electromagnetic targeting purposes [DIXON84].
Appropriate suppression of UE is also mandatory.

Communications networks for voice, data and services should employ topologies with
sufficient redundancy and failover mechanisms to allow operation with multiple nodes and
links inoperative. This will deny a user of electromagnetic bombs the option of disabling
large portions if not the whole of the network by taking down one or more key nodes or
links with a single or small number of attacks.

8. Limitations of Electromagnetic Bombs

The limitations of electromagnetic weapons are determined by weapon implementation and
means of delivery. Weapon implementation will determine the electromagnetic field strength
achievable at a given radius, and its spectral distribution. Means of delivery will
constrain the accuracy with which the weapon can be positioned in relation to the intended
target. Both constrain lethality.

In the context of targeting military equipment, it must be noted that thermionic
technology (ie vacuum tube equipment) is substantially more resilient to the
electromagnetic weapons effects than solid state (ie transistor) technology. Therefore a
weapon optimised to destroy solid state computers and receivers may cause little or no
damage to a thermionic technology device, for instance early 1960s Soviet military
equipment. Therefore a hard electrical kill may not be achieved against such targets
unless a suitable weapon is used.

This underscores another limitation of electromagnetic weapons, which is the difficulty
in kill assessment. Radiating targets such as radars or communications equipment may
continue to radiate after an attack even though their receivers and data processing
systems have been damaged or destroyed. This means that equipment which has been
successfully attacked may still appear to operate. Conversely an opponent may shut down an
emitter if attack is imminent and the absence of emissions means that the success or
failure of the attack may not be immediately apparent.

Assessing whether an attack on a non radiating emitter has been successful is more
problematic. A good case can be made for developing tools specifically for the purpose of
analysing unintended emissions, not only for targeting purposes, but also for kill
assessment.

An important factor in assessing the lethal coverage of an electromagnetic weapon is
atmospheric propagation. While the relationship between electromagnetic field strength and
distance from the weapon is one of an inverse square law in free space, the decay in
lethal effect with increasing distance within the atmosphere will be greater due quantum
physical absorption effects [10]. This is particularly so at
higher frequencies, and significant absorption peaks due water vapour and oxygen exist at
frequencies above 20 GHz. These will therefore contain the effect of HPM weapons to
shorter radii than are ideally achievable in the K and L frequency bands.

Means of delivery will limit the lethality of an electromagnetic bomb by introducing
limits to the weapon's size and the accuracy of its delivery. Should the delivery error be
of the order of the weapon's lethal radius for a given detonation altitude, lethality will
be significantly diminished. This is of particular importance when assessing the lethality
of unguided electromagnetic bombs, as delivery errors will be more substantial than those
experienced with guided weapons such as GPS guided bombs.

Therefore accuracy of delivery and achievable lethal radius must be considered against
the allowable collateral damage for the chosen target. Where collateral electrical damage
is a consideration, accuracy of delivery and lethal radius are key parameters. An
inaccurately delivered weapon of large lethal radius may be unusable against a target
should the likely collateral electrical damage be beyond acceptable limits. This can be a
major issue for users constrained by treaty provisions on collateral damage [AAP1003].

9. The Proliferation of Electromagnetic Bombs

At the time of writing, the United States and the CIS are the only two nations with the
established technology base and the depth of specific experience to design weapons based
upon this technology. However, the relative simplicity of the FCG and the Vircator
suggests that any nation with even a 1940s technology base, once in possession of
engineering drawings and specifications for such weapons, could manufacture them.

As an example, the fabrication of an effective FCG can be accomplished with basic
electrical materials, common plastic explosives such as C-4 or Semtex, and readily
available machine tools such as lathes and suitable mandrels for forming coils.
Disregarding the overheads of design, which do not apply in this context, a two stage FCG
could be fabricated for a cost as low as $1,000-2,000, at Western labour rates
[REINOVSKY85]. This cost could be even lower in a Third World or newly industrialised
economy.

While the relative simplicity and thus low cost of such weapons can be considered of
benefit to First World nations intending to build viable war stocks or maintain production
in wartime, the possibility of less developed nations mass producing such weapons is
alarming. The dependence of modern economies upon their information technology
infrastructure makes them highly vulnerable to attack with such weapons, providing that
these can be delivered to their targets.

Of major concern is the vulnerability resulting from increasing use of communications
and data communications schemes based upon copper cable media. If the copper medium were
to be replaced en masse with optical fibre in order to achieve higher bandwidths, the
communications infrastructure would become significantly more robust against
electromagnetic attack as a result. However, the current trend is to exploit existing
distribution media such as cable TV and telephone wiring to provide multiple Megabit/s
data distribution (eg cable modems, ADSL/HDSL/VDSL) to premises. Moreover, the gradual
replacement of coaxial Ethernet networking with 10-Base-T twisted pair equipment has
further increased the vulnerability of wiring systems inside buildings. It is not
unreasonable to assume that the data and services communications infrastructure in the
West will remain a "soft" electromagnetic target in the forseeable future.

At this time no counter-proliferation regimes exist. Should treaties be agreed to limit
the proliferation of electromagnetic weapons, they would be virtually impossible to
enforce given the common availability of suitable materials and tools.

With the former CIS suffering significant economic difficulties, the possibility of CIS
designed microwave and pulse power technology leaking out to Third World nations or
terrorist organisations should not be discounted. The threat of electromagnetic bomb
proliferation is very real.

10. A Doctrine for the Use of Conventional Electromagnetic Bombs

A fundamental tenet of IW is that complex organisational systems such as governments,
industries and military forces cannot function without the flow of information through
their structures. Information flows within these structures in several directions, under
typical conditions of function. A trivial model for this function would see commands and
directives flowing outward from a central decisionmaking element, with information about
the state of the system flowing in the opposite direction. Real systems are substantially
more complex.

This is of military significance because stopping this flow of information will
severely debilitate the function of any such system. Stopping the outward flow of
information produces paralysis, as commands cannot reach the elements which are to execute
them. Stopping the inward flow of information isolates the decisionmaking element from
reality, and thus severely inhibits its capacity to make rational decisions which are
sensitive to the currency of information at hand.

The recent evolution of strategic (air) warfare indicates a growing trend toward
targeting strategies which exploit this most fundamental vulnerability of any large and
organised system [11]. The Desert Storm air war of 1991 is a
good instance, with a substantial effort expended against such targets. Indeed, the model
used for modern strategic air attack places leadership and its supporting communications
in the position of highest targeting priority [WARDEN95]. No less importantly, modern
Electronic Combat concentrates upon the disruption and destruction of communications and
information gathering sensors used to support military operations. Again the Desert Storm
air war provides a good illustration of the application of this method.

A strategy which stresses attack upon the information processing and communications
elements of the systems which it is targeting offers a very high payoff, as it will
introduce an increasing level of paralysis and disorientation within its target.
Electromagnetic bombs are a powerful tool in the implementation of such a strategy.

10.1 Electronic Combat Operations using Electromagnetic Bombs

The central objective of Electronic Combat (EC) operations is the command of the
electromagnetic spectrum, achieved by soft and hard kill means [12]
against the opponent's electronic assets. The underlying objective of commanding the
electromagnetic spectrum is to interrupt or substantially reduce the flow of information
through the opponent's air defence system, air operations environment and between
functional elements of weapon systems.

In this context the ability of electromagnetic bombs to achieve kills against a wide
range of target types allows their general application to the task of inflicting attrition
upon an opponent's electronic assets, be they specialised air defence assets or more
general Command-Control-Communications (C3) and other military assets.

Electromagnetic bombs can be a means of both soft and hard electrical kill, subject to
the lethality of the weapon and the hardness of its target. A hard electrical kill by
means of an electromagnetic device will be achieved in those instances where such severe
electrical damage is achieved against a target so as to require the replacement of most if
not all of its internal electronics.

Electronic combat operations using electromagnetic devices involve the use of these to
attack radar, C3 and air defence weapon systems. These should always be attacked initially
with an electromagnetic weapon to achieve soft or hard electrical kills, followed up by
attack with conventional munitions to preclude possible repair of disabled assets at a
later time. As with conventional SEAD operations, the greatest payoff will be achieved by
using electromagnetic weapons against systems of strategic importance first, followed in
turn by those of operational and tactical importance [KOPP92].

In comparison with an AntiRadiation Missile (ARM - a missile which homes on the
emissions from a threat radar), the established and specialised tool in the conduct of
SEAD operations, an electromagnetic bomb can achieve kills against multiple targets of
diverse types within its lethal footprint. In this respect an electromagnetic device may
be described as a Weapon of Electrical Mass Destruction (WEMD). Therefore electromagnetic
weapons are a significant force multiplier in electronic combat operations.

A conventional electronic combat campaign, or intensive electronic combat operations,
will initially concentrate on saturating the opponent's electronic defences, denying
information and inflicting maximum attrition upon electronic assets. The force
multiplication offered by electromagnetic weapons vastly reduces the number of air assets
required to inflict substantial attrition, and where proper electronic reconnaissance has
been carried out beforehand, also reduces the need for specialised assets such as ARM
firing aircraft equipped with costly emitter locating systems.

The massed application of electromagnetic bombs in the opening phase of an electronic
battle will allow much faster attainment of command of the electromagnetic spectrum, as it
will inflict attrition upon electronic assets at a much faster rate than possible with
conventional means.

Whilst the immaturity of conventional electromagnetic weapons precludes an exact
analysis of the scale of force multiplication achievable, it is evident that a single
aircraft carrying an electromagnetic bomb capable of concurrently disabling a SAM site
with its colocated acquisition radar and supporting radar directed AAA weapons, will have
the potency of the several ARM firing and support jamming aircraft required to accomplish
the same result by conventional means. This and the ability of multirole tactical aircraft
to perform this task allows for a much greater concentration of force in the opening phase
of the battle, for a given force size.

In summary the massed application of electromagnetic weapons to Electronic Combat
operations will provide for a much faster rate of attrition against hostile electronic
assets, achievable with a significantly reduced number of specialised and multirole air
assets [13]. This will allow even a modestly sized force to
apply overwhelming pressure in the initial phase of an electronic battle, and therefore
achieve command of the electromagnetic spectrum in a significantly shorter time than by
conventional means.

10.2. Strategic Air Attack Operations using Electromagnetic Bombs

The modern approach to strategic air warfare reflects in many respects aspects of the
IW model, in that much effort is expended in disabling an opponent's fundamental
information processing infrastructure. Since we however are yet to see a systematic IW
doctrine which has been tested in combat, this paper will approach the subject from a more
conservative viewpoint and use established strategic doctrine.

Modern strategic air attack theory is based upon Warden's Five Rings model [WARDEN95],
which identifies five centres of gravity in a nation's warfighting capability. In
descending order of importance, these are the nation's leadership and supporting C3
system, its essential economic infrastructure, its transportation network, its population
and its fielded military forces.

Electromagnetic weapons may be productively used against all elements in this model,
and provide a particularly high payoff when applied against a highly industrialised and
geographically concentrated opponent. Of particular importance in the context of strategic
air attack, is that while electromagnetic weapons are lethal to electronics, they have
little if any effect on humans. This is a characteristic which is not shared with
established conventional and nuclear weapons.

This selectivity in lethal effect makes electromagnetic weapons far more readily
applicable to a strategic air attack campaign, and reduces the internal political pressure
which is experienced by the leadership of any democracy which must commit to warfare. An
opponent may be rendered militarily, politically and economically ineffective with little
if any loss in human life.

The innermost ring in the Warden model essentially comprises government bureaucracies
and civilian and military C3 systems. In any modern nation these are heavily dependent
upon the use of computer equipment and communications equipment. What is of key importance
at this time is an ongoing change in the structure of computing facilities used in such
applications, as these are becoming increasingly decentralised. A modern office
environment relies upon a large number of small computers, networked to interchange
information, in which respect it differs from the traditional model of using a small
number of powerful central machines.

This decentralisation and networking of information technology systems produces a major
vulnerability to electromagnetic attack. Whereas a small number of larger computers could
be defended against electromagnetic attack by the use of electromagnetic hardened computer
rooms, a large distributed network cannot. Moreover, unless optical fibre networking is
used, the networking cables are themselves a medium via which electromagnetic effects can
be efficiently propagated throughout the network, to destroy machines. Whilst the use of
distributed computer networks reduces vulnerability to attack by conventional munitions,
it increases vulnerability to attack by electromagnetic weapons.

Selective targeting of government buildings with electromagnetic weapons will result in
a substantial reduction in a government's ability to handle and process information. The
damage inflicted upon information records may be permanent, should inappropriate backup
strategies have been used to protect stored data. It is reasonable to expect most data
stored on machines which are affected will perish with the host machine, or become
extremely difficult to recover from damaged storage devices.

The cost of hardening existing computer networks is prohibitive, as is the cost of
replacement with hardened equipment. Whilst the use of hardened equipment for critical
tasks would provide some measure of resilience, the required discipline in the handling of
information required to implement such a scheme renders its utility outside of military
organisations questionable. Therefore the use of electromagnetic weapons against
government facilities offers an exceptionally high payoff.

Other targets which fall into the innermost ring may also be profitably attacked.
Satellite link and importantly control facilities are vital means of communication as well
as the primary interface to military and commercial reconnaissance satellites. Television
and radio broadcasting stations, one of the most powerful tools of any government, are
also vulnerable to electromagnetic attack due the very high concentration of electronic
equipment in such sites. Telephone exchanges, particularly later generation digital
switching systems, are also highly vulnerable to appropriate electromagnetic attack.

In summary the use of electromagnetic weapons against leadership and C3 targets is
highly profitable, in that a modest number of weapons appropriately used can introduce the
sought state of strategic paralysis, without the substantial costs incurred by the use of
conventional munitions to achieve the same effect.

Essential economic infrastructure is also vulnerable to electromagnetic attack. The
finance industry and stock markets are almost wholly dependent upon computers and their
supporting communications. Manufacturing, chemical, petroleum product industries and
metallurgical industries rely heavily upon automation which is almost universally
implemented with electronic PLC (Programmable Logic Controller) systems or digital
computers. Furthermore, most sensors and telemetry devices used are electrical or
electronic.

Attacking such economic targets with electromagnetic weapons will halt operations for
the time required to either repair the destroyed equipment, or to reconfigure for manual
operation. Some production processes however require automated operation, either because
hazardous conditions prevent human intervention, or the complexity of the control process
required cannot be carried out by a human operator in real time. A good instance are
larger chemical, petrochemical and oil/gas production facilities. Destroying automated
control facilities will therefore result in substantial loss of production, causing
shortages of these vital materials.

Manufacturing industries which rely heavily upon robotic and semiautomatic machinery,
such as the electronics, computer and electrical industry, precision machine industry and
aerospace industries, are all key assets in supporting a military capability. They are all
highly vulnerable to electromagnetic attack. Whilst material processing industries may in
some instances be capable of function with manual process control, the manufacturing
industries are almost wholly dependent upon their automated machines to achieve any useful
production output.

Historical experience [14] suggests that manufacturing
industries are highly resilient to air attack as production machinery is inherently
mechanically robust and thus a very high blast overpressure is required to destroy it. The
proliferation of electronic and computer controlled machinery has produced a major
vulnerability, for which historical precedent does not exist. Therefore it will be
necessary to reevaluate this orthodoxy in targeting strategy.

The finance industry and stock markets are a special case in this context, as the
destruction of their electronic infrastructure can yield, unlike manufacturing industries,
much faster economic dislocation. This can in turn produce large systemic effects across a
whole economy, including elements which are not vulnerable to direct electromagnetic
attack. This may be of particular relevance when dealing with an opponent which does not
have a large and thus vulnerable manufacturing economy. Nations which rely on agriculture,
mining or trade for a large proportion of the their gross domestic product are prime
candidates for electromagnetic attack on their finance industry and stock markets. Since
the latter are usually geographically concentrated and typically electromagnetically
"soft" targets, they are highly vulnerable.

In summary there is a large payoff in striking at economic essentials with
electromagnetic weapons, particularly in the opening phase of a strategic air attack
campaign, as economic activity may be halted or reduced with modest expenditure of the
attacker's resources. An important caveat is that centres of gravity within the target
economy must be properly identified and prioritised for strikes to ensure that maximum
effect is achieved as quickly as possible.

Transport infrastructure is the third ring in the Warden model, and also offers some
useful opportunities for the application of electromagnetic weapons. Unlike the innermost
rings, the concentration of electronic and computer equipment is typically much lower, and
therefore considerable care must be taken in the selection of targets.

Railway and road signalling systems, where automated, are most vulnerable to
electromagnetic attack on their control centres. This could be used to produce traffic
congestion by preventing the proper scheduling of rail traffic, and disabling road traffic
signalling, although the latter may not yield particularly useful results.

Significantly, most modern automobiles and trucks use electronic ignition systems which
are known to be vulnerable to electromagnetic weapons effects, although opportunities to
find such concentrations so as to allow the profitable use of an electromagnetic bomb may
be scarce.

The population of the target nation is the fourth ring in the Warden model, and its
morale is the object of attack. The morale of the population will be affected
significantly by the quality and quantity of the government propaganda it is subjected to,
as will it be affected by living conditions.

Using electromagnetic weapons against urban areas provides the opportunity to prevent
government propaganda from reaching the population via means of mass media, through the
damaging or destruction of all television and radio receivers within the footprint of the
weapon. Whether this is necessary, given that broadcast facilities may have already been
destroyed, is open to discussion. Arguably it may be counterproductive, as it will prevent
the target population from being subjected to friendly means of psychological warfare such
as propaganda broadcasts.

The use of electromagnetic weapons against a target population is therefore an area
which requires requires careful consideration in the context of the overall IW campaign
strategy. If useful objectives can be achieved by isolating the population from government
propaganda, then the population is a valid target for electromagnetic attack. Forces
constrained by treaty obligations will have to reconcile this against the applicable
regulations relating to denial of services to non-combatants [AAP1003].

The outermost and last ring in the Warden model are the fielded military forces. These
are by all means a target vulnerable to electromagnetic attack, and C3 nodes, fixed
support bases as well as deployed forces should be attacked with electromagnetic devices.
Fixed support bases which carry out depot level maintenance on military equipment offer a
substantial payoff, as the concentration of computers in both automatic test equipment and
administrative and logistic support functions offers a good return per expended weapon.

Any site where more complex military equipment is concentrated should be attacked with
electromagnetic weapons to render the equipment unservicable and hence reduce the fighting
capability, and where possible also mobility of the targeted force. As discussed earlier
in the context of Electronic Combat, the ability of an electromagnetic weapon to achieve
hard electrical kills against any non-hardened targets within its lethal footprint
suggests that some target sites may only require electromagnetic attack to render them
both undefended and non-operational. Whether to expend conventional munitions on targets
in this state would depend on the immediate military situation.

In summary the use of electromagnetic weapons in strategic air attack campaign offers a
potentially high payoff, particularly when applied to leadership, C3 and vital economic
targets, all of which may be deprived of much of their function for substantial periods of
time. The massed application of electromagnetic weapons in the opening phase of the
campaign would introduce paralysis within the government, deprived of much of its
information processing infrastructure, as well as paralysis in most vital industries. This
would greatly reduce the capability of the target nation to conduct military operations of
any substantial intensity.

Because conventional electromagnetic weapons produce negligible collateral damage,
in comparison with conventional explosive munitions, they allow the conduct of an
effective and high tempo campaign without the loss of life which is typical of
conventional campaigns. This will make the option of a strategic bombing campaign more
attractive to a Western democracy, where mass media coverage of the results of
conventional strategic strike operations will adversely affect domestic civilian morale.

The long term effects of a sustained and concentrated strategic bombing campaign using
a combination of conventional and electromagnetic weapons will be important. The cost of
computer and communications infrastructure is substantial, and its massed destruction
would be a major economic burden for any industrialised nation. In addition it is likely
that poor protection of stored data will add to further economic losses, as much data will
be lost with the destroyed machines.

From the perspective of conducting an IW campaign, this method of attack achieves many
of the central objectives sought. Importantly, the massed application of electromagnetic
weapons would inflict attrition on an opponent's information processing infrastructure
very rapidly, and this would arguably add a further psychological dimension to the potency
of the attack. Unlike the classical IW model of Gibsonian CyberWar, in which the opponent
can arguably isolate his infrastructure from hostile penetration, parallel or hyperwar
style massed attack with electromagnetic bombs will be be extremely difficult to defend
against.

10.3. Offensive Counter Air (OCA) Operations using Electromagnetic Bombs

Electromagnetic bombs may be usefully applied to OCA operations. Modern aircraft are
densely packed with electronics, and unless properly hardened, are highly vulnerable
targets for electromagnetic weapons.

The cost of the onboard electronics represents a substantial fraction of the total cost
of a modern military aircraft, and therefore stock levels of spares will in most instances
be limited to what is deemed necessary to cover operational usage at some nominal sortie
rate. Therefore electromagnetic damage could render aircraft unusable for substantial
periods of time.

Attacking airfields with electromagnetic weapons will disable communications, air
traffic control facilities, navigational aids and operational support equipment, if these
items are not suitably electromagnetic hardened. Conventional blast hardening measures
will not be effective, as electrical power and fixed communications cabling will carry
electromagnetic induced transients into most buildings. Hardened aircraft shelters may
provide some measure of protection due electrically conductive reinforcement embedded in
the concrete, but conventional revetments will not.

Therefore OCA operations against airfields and aircraft on the ground should include
the use of electromagnetic weapons as they offer the potential to substantially reduce
hostile sortie rates.

10.4. Maritime Air Operations using Electromagnetic Bombs

As with modern military aircraft, naval surface combatants are fitted with a
substantial volume of electronic equipment, performing similar functions in detecting and
engaging targets and warning of attack. As such they are vulnerable to electromagnetic
attack, if not suitably hardened. Should they be hardened, volumetric, weight and cost
penalties will be incurred.

Conventional methods for attacking surface combatants involve the use of saturation
attacks by anti-ship missiles or coordinated attacks using a combination of ARMs and
anti-ship missiles. The latter instance is where disabling the target electronically by
stripping its antennae precedes lethal attack with specialised anti-ship weapons.

An electromagnetic warhead detonated within lethal radius of a surface combatant will
render its air defence system inoperable, as well as damaging other electronic equipment
such as electronic countermeasures, electronic support measures and communications. This
leaves the vessel undefended until these systems can be restored, which may or may not be
possible on the high seas. Therefore launching an electromagnetic glidebomb on to a
surface combatant, and then reducing it with laser or television guided weapons is an
alternate strategy for dealing with such targets.

10.5. Battlefield Air Interdiction Operations using Electromagnetic Bombs

Modern land warfare doctrine emphasises mobility, and manoeuvre warfare methods are
typical for contemporary land warfare. Coordination and control are essential to the
successful conduct of manoeuvre operations, and this provides another opportunity to apply
electromagnetic weapons. Communications and command sites are key elements in the
structure of such a land army, and these concentrate communications and computer
equipment. Therefore they should be attacked with electromagnetic weapons, to disrupt the
command and control of land operations.

Should concentrations of armoured vehicles be found, these are also profitable targets
for electromagnetic attack, as their communications and fire control systems may be
substantially damaged or disabled as a result. A useful tactic would be initial attack
with electromagnetic weapons to create a maximum of confusion, followed by attack with
conventional weapons to take advantage of the immediate situation.

10.6. Defensive Counter-Air (DCA) and Air Defence Operations using Electromagnetic
Warheads

Providing that compact electromagnetic warheads can be built with useful lethality
performance, then a number of other potential applications become viable. One is to equip
an Air-Air Missile (AAM) with such a warhead. A weapon with datalink midcourse guidance,
such as the AIM-120, could be used to break up inbound raids by causing soft or hard
electrical kills in a formation (raid) of hostile aircraft. Should this be achieved, the
defending fighter will have the advantage in any following engagement as the hostile
aircraft may not be fully mission capable. Loss of air intercept or nav attack radar, EW
equipment, mission computers, digital engine controls, communications and electronic
flight controls, where fitted, could render the victim aircraft defenceless against attack
with conventional missiles.

This paradigm may also be applied to air defence operations using area defence SAMs.
Large SAMs such as the MIM-104 Patriot, RIM-66E/M and RIM-67A Standard, 5V55/48N6 (SA-10)
and 9M82/9M83 (SA-12) could accommodate an electromagnetic warhead comparable in size to a
bomb warhead. A SAM site subjected to jamming by inbound bombers could launch a first
round under datalink control with an electromagnetic warhead to disable the bombers, and
then follow with conventional rounds against targets which may not be able to defend
themselves electronically. This has obvious implications for the electromagnetic hardness
of combat aircraft systems.

10.7. A Strategy of Graduated Response

The introduction of non-nuclear electromagnetic bombs into the arsenal of a modern air
force considerably broadens the options for conducting strategic campaigns. Clearly such
weapons are potent force multipliers in conducting a conventional war, particularly when
applied to Electronic Combat, OCA and strategic air attack operations.

The massed use of such weapons would provide a decisive advantage to any nation with
the capability to effectively target and deliver them. The qualitative advantage in
capability so gained would provide a significant advantage even against a much stronger
opponent not in the possession of this capability.

Electromagnetic weapons however open up less conventional alternatives for the conduct
of a strategic campaign, which derive from their ability to inflict significant material
damage without inflicting visible collateral damage and loss of life. Western governments
have been traditionally reluctant to commit to strategic campaigns, as the expectation of
a lengthy and costly battle, with mass media coverage of its highly visible results, will
quickly produce domestic political pressure to cease the conflict.

An alternative is a Strategy of Graduated Response (SGR). In this strategy, an opponent
who threatens escalation to a full scale war is preemptively attacked with electromagnetic
weapons, to gain command of the electromagnetic spectrum and command of the air. Selective
attacks with electromagnetic weapons may then be applied against chosen strategic targets,
to force concession. Should these fail to produce results, more targets may be disabled by
electromagnetic attack. Escalation would be sustained and graduated, to produce steadily
increasing pressure to concede the dispute. Air and sea blockade are complementary means
via which pressure may be applied.

Because electromagnetic weapons can cause damage on a large scale very quickly, the
rate at which damage can be inflicted can be very rapid, in which respect such a campaign
will differ from the conventional, where the rate at which damage is inflicted is limited
by the usable sortie rate of strategic air attack capable assets [15].

Should blockade and the total disabling of vital economic assets fail to yield results,
these may then be systematically reduced by conventional weapons, to further escalate the
pressure. Finally, a full scale conventional strategic air attack campaign would follow,
to wholly destroy the hostile nation's warfighting capability.

Another situation where electromagnetic bombs may find useful application is in dealing
with governments which actively implement a policy of state sponsored terrorism or
info-terrorism, or alternately choose to conduct a sustained low intensity land warfare
campaign. Again the Strategy of Graduated Response, using electromagnetic bombs in the
initial phases, would place the government under significant pressure to concede.

Importantly, high value targets such as R&D and production sites for Weapons of
Mass Destruction (nuclear, biological, chemical) and many vital economic sites, such as
petrochemical production facilities, are critically dependent upon high technology
electronic equipment. The proliferation of WMD into developing nations has been greatly
assisted by the availability of high quality test and measurement equipment commercially
available from First World nations, as well as modern electronic process control
equipment. Selectively destroying such equipment can not only paralyse R&D effort, but
also significantly impair revenue generating production effort. A Middle Eastern nation
sponsoring terrorism will use oil revenue to support such activity. Crippling its primary
source of revenue without widespread environmental pollution may be an effective and
politically acceptable punitive measure.

As a punitive weapon electromagnetic devices are attractive for dealing with
belligerent governments. Substantial economic, military and political damage may be
inflicted with a modest commitment of resources by their users, and without politically
damaging loss of life.

11. Conclusions

Electromagnetic bombs are Weapons of Electrical Mass Destruction with applications
across a broad spectrum of targets, spanning both the strategic and tactical. As such
their use offers a very high payoff in attacking the fundamental information processing
and communication facilities of a target system. The massed application of these weapons
will produce substantial paralysis in any target system, thus providing a decisive
advantage in the conduct of Electronic Combat, Offensive Counter Air and Strategic Air
Attack.

Because E-bombs can cause hard electrical kills over larger areas than conventional
explosive weapons of similar mass, they offer substantial economies in force size for a
given level of inflicted damage, and are thus a potent force multiplier for appropriate
target sets.

The non-lethal nature of electromagnetic weapons makes their use far less politically
damaging than that of conventional munitions, and therefore broadens the range of military
options available.

This paper has included a discussion of the technical, operational and targeting
aspects of using such weapons, as no historical experience exists as yet upon which to
build a doctrinal model. The immaturity of this weapons technology limits the scope of
this discussion, and many potential areas of application have intentionally not been
discussed. The ongoing technological evolution of this family of weapons will clarify the
relationship between weapon size and lethality, thus producing further applications and
areas for study.

E-bombs can be an affordable force multiplier for military forces which are under post
Cold War pressures to reduce force sizes, increasing both their combat potential and
political utility in resolving disputes. Given the potentially high payoff deriving from
the use of these devices, it is incumbent upon such military forces to appreciate both the
offensive and defensive implications of this technology. It is also incumbent upon
governments and private industry to consider the implications of the proliferation of this
technology, and take measures to safeguard their vital assets from possible future attack.
Those who choose not to may become losers in any future wars.

12. Acknowledgements

Thanks to Dr D.H. Steven for his insightful comment on microwave coupling and
propagation, and to Professor C.S. Wallace, Dr Ronald Pose and Dr Peter Leigh-Jones for
their most helpful critique of the drafts. Thanks also to the RAAF Air Power Studies
Centre and its then Director, Group Captain Gary Waters, for encouraging the author to
investigate this subject in 1993. Some material in this paper is derived from RAAF APSC
Working Paper 15, "A Doctrine for the Use of Electromagnetic Pulse Bombs",
published in 1993 [KOPP93], and is posted with permission.

An earlier version of this paper was presented at InfoWarCon V and first published in
"Information Warfare - Cyberterrorism: Protecting Your Personal Security In the
Electronic Age", 1996, Thunder's Mouth Press, 632 Broadway 7th FL, New York, NY,
ISBN: 1-56025-132-8, http://www.infowar.com, posted with permission.

13. References

AAP1000 - RAAF, DI(AF) AAP1000, The Air Power Manual, Second Edition, RAAF APSC,
Canberra, 1994

AAP1003 - RAAF, DI(AF) AAP1003, Ch.8 The Law of Aerial Targeting, Operations Law for
RAAF Commanders, First Edition, RAAF APSC, Canberra, 1994

AFM1-1 - Basic Aerospace Doctrine of the United States Air Force, Air Force Manual 1-1,
Volume 1, March 1992.

CAIRD85 - Caird R.S. et al, Tests of an Explosive Driven Coaxial Generator, Digest of
Technical Papers, 5th IEEE Pulsed Power Conference, pp.220, IEEE, New York, 1985.

DIXON84 - Dixon R.C., Spread Spectrum Systems, John Wiley and Sons, New York, 1984.

FANTHOME89 - Fanthome B.A., MHD Pulsed Power Generation, Digest of Technical Papers,
7th IEEE Pulsed Power Conference, pp.483, IEEE, New York, 1989.

FLANAGAN81 - Flanagan J., High-Performance MHD Solid Gas Generator, Naval Research Lab,
Patent Application 4269637, May 1981.

FOWLER60 - C. M. Fowler, W. B. Garn, and R. S. Caird, Production of Very High Magnetic
Fields by Implosion, Journal of Applied Physics, Vol. 31, No. 3, 588-594, March, 1960.

FOWLER89 - C. M. Fowler,R. S. Caird, The Mark IX Generator, Digest of Technical Papers,
Seventh IEEE Pulsed Power Conference, 475, IEEE, New York, 1989.

FULGHUM93 - Fulghum, D.A., ALCMs Given Non Lethal Role, Aviation Week & Space
Technology, February 22, 1993.

GLASSTONE64 - S. Glasstone, Editor, The Effects of Nuclear Weapons, US AEC, April,
1962, Revised Edition February, 1964.

GOFORTH89 - Goforth J.H. et al, Experiments with Explosively Formed Fuse Opening
Switches in Higher Efficiency Circuits, Digest of Technical Papers, 7th IEEE Pulsed Power
Conference, pp.479, IEEE, New York, 1989.

GRANATSTEIN87 - Granatstein V.L., Alexeff I., High Power Microwave Sources, Artech
House, Boston, London, 1987

HERSKOVITZ96 - Herskowitz D., The Other SIGINT/ELINT, Journal of Electronic Defence,
April, 1996.

HOEBERLING92 - Heoberling R.F., Fazio M.V., Advances in Virtual Cathode Microwave
Sources, IEEE Transactions on Electromagnetic Compatibility, Vol. 34, No. 3, 252, August
1992.

ICH10 - EW Systems: AN/ Designated Hardware, pp.86, International Countermeasures
Handbook, 10th Edition, Cardiff Publishing, Colorado, 1985.

ICH14 - International Countermeasures Handbook, 14th Edition, Cardiff Publishing,
Colorado, 1989.

JED95 - USAF Looks for HPM SEAD Solution, pp.36, Journal of Electronic Defence,
September, 1995.

JED96 - Hughes to Build HPM SEAD Demonstrator, pp.29, Journal of Electronic Defence,
February, 1996.

KIRTLAND94 - High Energy Microwave Laboratory, Fact Sheet, USAF AFMC, Phillips
Laboratory, Kirtland AFB, 1994.

KOPP92 - Kopp C., Command of the Electromagnetic Spectrum - An Electronic Combat
Doctrine for the RAAF, Working Paper No.8, Air Power Studies Centre, Royal Australian Air
Force, Canberra, November 1992.

KOPP93 - Kopp C., A Doctrine for the Use of Electromagnetic Pulse Bombs, Working Paper
No.15, Air Power Studies Centre, Royal Australian Air Force, Canberra, July 1993.

KOPP96 - Kopp C., Australia's Kerkanya Based Agile Gliding Weapon, pp.28, Australian
Aviation, Aerospace Publications, Canberra, June 1996.

KRAUS88 - Kraus J.D., Antennas, Second Edition, McGraw-Hill, 1988.

MDC95 - Joint Direct Attack Munition (JDAM), unclassified briefing, McDonnell Douglas
Corporation, 1995, unpublished material.

MICRON92 - Micron DRAM Data Book, Micron Technology Inc, Idaho, 1992.

MOTO3 - Motorola RF Device Data, Motorola Semiconductor Products Inc, Arizona, 1983.

NATSEMI78 - CMOS Databook, National Semiconductor Corporation, Santa Clara, 1978

NORTHROP95 - B-2 Precision Weapons, unclassified briefing, Northrop-Grumman
Corporation, September, 1995, unpublished material.

NPI93 - NPI Local Area Network Products, SMD Transformers, Nano Pulse Industries, Brea,
1993.

PERGLER94 - Pergler R., Joint Standoff Weapon System (JSOW), unclassified briefing,
Texas Instruments, Inc., December 1994, unpublished material.

RAMO65 - Ramo S. et al, Fields and Waves in Communications Electronics, New York, John
Wiley & Sons, 1965

REINOVSKY85 - Reinovsky R.E., Levi P.S. and Welby J.M., An Economical, 2 Stage Flux
Compression Generator System, Digest of Technical Papers, 5th IEEE Pulsed Power
Conference, pp.216, IEEE, New York, 1985.

SANDER86 - Sander K. F. and G.A.L. Reed, Transmission and Propagation of
Electromagnetic Waves, Cambridge University Press, 1986.

STAINES93 - Staines, G.W., High Power Microwave Technology - Part IV, Military
Applications of High Power Microwaves, Salisbury, DSTO ERL, EWD, 1993, draft paper.

SZAFRANSKI95 - Szafranski R., Col USAF, Parallel War and Hyperwar, Chapter 5 in
Schneider B.R, Grinter L.E., Battlefield of the Future, 21st Century Warfare Issues, Air
University Press, Maxwell AFB, September 1995.

TAYLOR92 - Taylor C.D., Harrison C.W., On the Coupling of Microwave Radiation to Wire
Structures, IEEE Transactions on Electromagnetic Compatibility, Vol. 34, No. 3, 183,
August 1992.

THODE87 - Thode L.E., Virtual-Cathode Microwave Device Research: Experiment and
Simulation, Chapter 14 in High Power Microwave Sources, 1987.

VECK85 - van Eck W., "Electromagnetic Radiation from Video Display Units: An
Eavesdropping Risk", Computers and Security, 1985, pp. 269.

WARDEN95 - Warden J.A. III, Col USAF, Air Theory for the Twenty-first Century, Chapter
4 in Schneider B.R, Grinter L.E., Battlefield of the Future, 21st Century Warfare Issues,
Air University Press, Maxwell AFB, September 1995.

WATERS92 - Waters Gary, Gulf Lesson One, Canberra, Air Power Studies Centre, 1992

WHITE78 - The EMP - A Triangular Impulse, 2.29, A Handbook Series on Electromagnetic
Interference and Compatibility, Don White Consultants, Maryland, 1978.

Carlo Kopp Born in Perth, Western Australia, the author graduated with
first class honours in Electrical Engineering in 1984, from the University of Western
Australia. In 1996 he completed an MSc in Computer Science and is currently working on a
PhD in the same discipline, at Monash University in Melbourne, Australia. He has over a
decade of diverse industry experience, including the design of high speed communications
equipment, optical fibre receivers and transmitters, communications equipment including
embedded code, Unix computer workstation motherboards, graphics adaptors and chassis. More
recently, he has consulted in Unix systems programming, performance engineering and system
administration. Actively publishing as a defence analyst in Australia's leading aviation
trade journal, Australian Aviation, since 1980, he has become a locally recognised
authority on the application of modern military technology to operations and strategy. His
work on electronic combat doctrine, electromagnetic weapons doctrine, laser remote sensing
and signature reduction has been published by the Royal Australian Air Force's Air Power
Studies Centre since 1992, and he has previously contributed to CADRE Air Chronicles.

1 - Electromagnetic pulse or EMP device is a generic term applied to
any device, nuclear or conventional, which is capable of generating a very intense but
short electromagnetic field transient. For weapons applications, this transient must be
sufficiently intense to produce electromagnetic power densities which are lethal to
electronic and electrical equipment. Electromagnetic weapons are electromagnetic devices
specifically designed as weapons. Whilst the terms 'conventional EMP weapon' and 'High
Power Microwave or HPM weapon' have been used interchangeably in trade journals (see
FULGHUM93), this paper will distinguish between microwave band and low frequency weapons.
The term 'electromagnetic bomb' or 'E-bomb' will be used to describe both microwave and
low frequency non-nuclear bombs. This paper will not address the use of nuclear EMP, or
alternate uses of HPM technology. HPM technology has a broad range of potential
applications in EW, radar and directed energy weapons (DEW). The general conclusions of
this paper in the areas of infrastructure vulnerability and hardening are also true for
microwave directed energy weapons. This paper extends the scope of earlier work by the
author on this subject [KOPP93].

2 - One bizzare instance of lightning strike electrical damage was
described to the author by an eyewitness technician, tasked with assessing the damage on
the site. A lightning bolt impacted in the close vicinity of a transmitter shed. RF and
power cables ran from the transmitter shed to a transmission tower through a rectangular,
metal shielded tunnel. The effect of the lightning strike was to produce an
electromagnetic standing wave in the tunnel, much like in a microwave waveguide. All
cables within the tunnel were burned through at regular spacings along the tunnel,
corresponding precisely to the half wavelength of the standing wave in the tunnel.

3 - The NACSIM 5100A standard specifies acceptable emission levels for
TEMPEST (Transient ElectroMagnetic Pulse Emanation Standard) rated equipment.

4 - The Northrop/Lockheed ASD-5 Black Crow DF receiver was fitted to
the AC-130A Pave Pronto gunships, rebuilt from obsoleted C-130 transports [ICH10].

5 - A noteworthy technical issue in this context is that even equipment
not-rated to TEMPEST standards will radiate energy at very low power levels, in comparison
with intentional transmissions by radar or communications equipment. A receiver designed
to detect, identify and locate sources of UE radiation will either need to be highly
sensitive, or deployed very close to the emitter. It is worth noting that UE from computer
monitors and networks exhibit known regular patterns, and correlation techniques could be
used to significantly improve receiver sensitivity [DIXON84].

6 - Fulghum D.A., ALCMs Given Non Lethal Role, AW&ST, Feb 22, 1993.
This recent report indicates that the US has progressed significantly with its development
work on electromagnetic warhead technology. An electromagnetic warhead was fitted to the
USAF AGM-86 Air Launched Cruise Missile airframe, involving both structural and guidance
system modifications. The description in this report suggests the use of an explosive
pumped flux generator feeding a device such as a Vircator. References to magnetic coils
almost certainly relate to the flux compression generator hardware.

7 - The Journal of Electronic Defence [JED96] recently reported on the
USAF Phillips Laboratory at Kirtland awarding a $6.6M HPM SEAD weapon technology
demonstration program contract to Hughes Missile Systems Co. This contract will see Hughes
conduct design studies in order to define design goals, and then fabricate brassboard
demonstration hardware using government developed technology. JED speculate that the
weapon will be a FCG driven microwave tube, which is most likely the case given the USAF's
prior research activities in this area [REINOVSKY85]. An earlier report [JED95] indicated
the existence of a related program which addresses command and control warfare and
counter-air capabilities. In any event, the devices produced by these programs are likely
to become the first operationally fielded HPM electromagnetic bombs for delivery by combat
aircraft.

8 - This may be readily determined by calculating the ratio of warhead
mass to total weapon launch mass, for representative missile types. Taking the AGM-78
Standard as a lower limit yields 15.9%, whereas taking the AGM/BGM-109 Tomahawk as an
upper limit yields about 28%. Figures are derived from manufacturers' brochures and
reference publications eg Jane's Air-Launched Weapons.

9 - Staines, Fulghum. This is entirely consistent with theoretical
expectations, as the different spectral characteristics of microwave electromagnetic
warheads, compared to nuclear electromagnetic weapons, will significantly affect the
effectiveness of protective filters. What is important from an electrical engineering
viewpoint is that a filter designed to stop signals in the lower frequency bands may
perform very poorly at microwave frequencies.

10 - See International Countermeasures Handbook, 14th Edition, pp 104.

11 - Gary Waters, Gulf Lesson One. Chapter 16 of this reference
provides a good discussion of both the rationale and implementation of this strategy.

12 - Soft kill means will inhibit or degrade the function of a target
system during their application, leaving the target system electrically and physically
intact upon the cessation of their application. Hard kill means will damage or destroy the
target system, and are thus a means of inflicting attrition.

13 - This is also the stated intent of the USAF HPM SEAD technology
demonstration program. The fact that the first application of a HPM bomb is electronic
combat underscores the tactical, operational and strategic importance of first defeating
an air defence system when prosecuting a strategic air war.

14 - The classical argument here is centred upon Allied experience in
bombing Germany during WW2, where even repeated raids on industrial targets were unable to
wholly stop production, and in many instances only served to reduce the rate of increase
in production. What must not be overlooked is that both the accuracy and lethality of
weapons in this period bore little comparison to what is available today, and automation
of production facilities was almost non-existent.

15- This constraint primarily results from limitations in numbers.
Strategic air attack requires precision delivery of substantial payloads, and is thus most
effectively performed with specialised bomber assets, such as the B-52, B-1, B-2, F-111,
F-15E, F-117A, Tornado or Su-24. These are typically more maintenance intensive than less
complex multirole fighters, and this will become a constraint to the sortie rate
achievable with a finite number of aircraft, assuming the availability of aircrew. Whilst
multirole fighters may be applied to strategic air attack, their typically lesser payload
radius performance and lesser accuracy will reduce their effectiveness. In the doctrinal
context, this can be directly related to existing USAF aerospace doctrine [AFM1-1], in
several areas.

A version of this article was first published in: "Information Warfare -
Cyberterroism: Protecting Your Personal Security in the Electronic Age" by Winn
Schwartau, 1996 Thunder's Mouth Press, 632 Broadway 7th Fl, New York, New York, ISBN:
1-56025-132-8, http://www.infowar.com

The conclusions and opinions expressed in this document are those of the author
cultivated in the freedom of expression, and academic environment of Air University. They
do not reflect the official position of the US Government, Department of Defense, the
United States Air Force or the Air University.

Aerospace
Power Chronicles Home Page | Feedback? Email to [email-masked]

---

From: "Gerard G. Cook" <[email-masked]>
Date: Tue, 10 Dec 2002 16:23:12 -0500

The Electromagnetic Bomb - a Weapon of Electrical Mass Destructioni always
liked this idea, now that we revisit- JUST IMAGINE, STRAP ON YOUR SOLDER
IRON AND NEVER ENDING SERVICE CALLS!   helluva way to run a war.
  -----Original Message-----
  From: Marcel [mailto:[email-masked]]
  Sent: Tuesday, December 10, 2002 2:07 PM
  To: WFHSG; [email-masked]
  Subject: [NEXTEL-1] The Electromagnetic Bomb - a Weapon of Electrical Mass
Destruction

       ABSTRACT
       High Power Electromagnetic Pulse generation techniques and High Power
Microwave technology have matured to the point where practical E-bombs
(Electromagnetic bombs) are becoming technically feasible, with new
applications in both Strategic and Tactical Information Warfare. The
development of conventional E-bomb devices allows their use in non-nuclear
confrontations. This paper discusses aspects of the technology base, weapon
delivery techniques and proposes a doctrinal foundation for the use of such
devices in warhead and bomb applications.

  1. Introduction
  The prosecution of a successful Information Warfare (IW) campaign against
an industrialised or post industrial opponent will require a suitable set of
tools. As demonstrated in the Desert Storm air campaign, air power has
proven to be a most effective means of inhibiting the functions of an
opponent's vital information processing infrastructure. This is because air
power allows concurrent or parallel engagement of a large number of targets
over geographically significant areas [SZAFRANSKI95].

  While Desert Storm demonstrated that the application of air power was the
most practical means of crushing an opponent's information processing and
transmission nodes, the need to physically destroy these with guided
munitions absorbed a substantial proportion of available air assets in the
early phase of the air campaign. Indeed, the aircraft capable of delivery
laser guided bombs were largely occupied with this very target set during
the first nights of the air battle.

  The efficient execution of an IW campaign against a modern industrial or
post-industrial opponent will require the use of specialised tools designed
to destroy information systems. Electromagnetic bombs built for this purpose
can provide, where delivered by suitable means, a very effective tool for
this purpose.

  2.The EMP Effect
  The ElectroMagnetic Pulse (EMP) effect [1] was first observed during the
early testing of high altitude airburst nuclear weapons [GLASSTONE64]. The
effect is characterised by the production of a very short (hundreds of
nanoseconds) but intense electromagnetic pulse, which propagates away from
its source with ever diminishing intensity, governed by the theory of
electromagnetism. The ElectroMagnetic Pulse is in effect an electromagnetic
shock wave.

  This pulse of energy produces a powerful electromagnetic field,
particularly within the vicinity of the weapon burst. The field can be
sufficiently strong to produce short lived transient voltages of thousands
of Volts (ie kiloVolts) on exposed electrical conductors, such as wires, or
conductive tracks on printed circuit boards, where exposed.

  It is this aspect of the EMP effect which is of military significance, as
it can result in irreversible damage to a wide range of electrical and
electronic equipment, particularly computers and radio or radar receivers.
Subject to the electromagnetic hardness of the electronics, a measure of the
equipment's resilience to this effect, and the intensity of the field
produced by the weapon, the equipment can be irreversibly damaged or in
effect electrically destroyed. The damage inflicted is not unlike that
experienced through exposure to close proximity lightning strikes, and may
require complete replacement of the equipment, or at least substantial
portions thereof.

  Commercial computer equipment is particularly vulnerable to EMP effects,
as it is largely built up of high density Metal Oxide Semiconductor (MOS)
devices, which are very sensitive to exposure to high voltage transients.
What is significant about MOS devices is that very little energy is required
to permanently wound or destroy them, any voltage in typically in excess of
tens of Volts can produce an effect termed gate breakdown which effectively
destroys the device. Even if the pulse is not powerful enough to produce
thermal damage, the power supply in the equipment will readily supply enough
energy to complete the destructive process. Wounded devices may still
function, but their reliability will be seriously impaired. Shielding
electronics by equipment chassis provides only limited protection, as any
cables running in and out of the equipment will behave very much like
antennae, in effect guiding the high voltage transients into the equipment.

  Computers used in data processing systems, communications systems,
displays, industrial control applications, including road and rail
signalling, and those embedded in military equipment, such as signal
processors, electronic flight controls and digital engine control systems,
are all potentially vulnerable to the EMP effect.

  Other electronic devices and electrical equipment may also be destroyed by
the EMP effect. Telecommunications equipment can be highly vulnerable, due
to the presence of lengthy copper cables between devices. Receivers of all
varieties are particularly sensitive to EMP, as the highly sensitive
miniature high frequency transistors and diodes in such equipment are easily
destroyed by exposure to high voltage electrical transients. Therefore radar
and electronic warfare equipment, satellite, microwave, UHF, VHF, HF and low
band communications equipment and television equipment are all potentially
vulnerable to the EMP effect.

  It is significant that modern military platforms are densely packed with
electronic equipment, and unless these platforms are well hardened, an EMP
device can substantially reduce their function or render them unusable.

  3. The Technology Base for Conventional Electromagnetic Bombs
  The technology base which may be applied to the design of electromagnetic
bombs is both diverse, and in many areas quite mature. Key technologies
which are extant in the area are explosively pumped Flux Compression
Generators (FCG), explosive or propellant driven Magneto-Hydrodynamic (MHD)
generators and a range of HPM devices, the foremost of which is the Virtual
Cathode Oscillator or Vircator. A wide range of experimental designs have
been tested in these technology areas, and a considerable volume of work has
been published in unclassified literature.

  This paper will review the basic principles and attributes of these
technologies, in relation to bomb and warhead applications. It is stressed
that this treatment is not exhaustive, and is only intended to illustrate
how the technology base can be adapted to an operationally deployable
capability.

  3.1. Explosively Pumped Flux Compression Generators
  The explosively pumped FCG is the most mature technology applicable to
bomb designs. The FCG was first demonstrated by Clarence Fowler at Los
Alamos National Laboratories (LANL) in the late fifties [FOWLER60]. Since
that time a wide range of FCG configurations has been built and tested, both
in the US and the USSR, and more recently CIS.

  The FCG is a device capable of producing electrical energies of tens of
MegaJoules in tens to hundreds of microseconds of time, in a relatively
compact package. With peak power levels of the order of TeraWatts to tens of
TeraWatts, FCGs may be used directly, or as one shot pulse power supplies
for microwave tubes. To place this in perspective, the current produced by a
large FCG is between ten to a thousand times greater than that produced by a
typical lightning stroke [WHITE78].

  The central idea behind the construction of FCGs is that of using a fast e
xplosive to rapidly compress a magnetic field, transferring much energy from
the explosive into the magnetic field.

  The initial magnetic field in the FCG prior to explosive initiation is
produced by a start current. The start current is supplied by an external
source, such a a high voltage capacitor bank (Marx bank), a smaller FCG or
an MHD device. In principle, any device capable of producing a pulse of
electrical current of the order of tens of kiloAmperes to MegaAmperes will
be suitable.

  A number of geometrical configurations for FCGs have been published (for
examples see REINOVSKY85, CAIRD85, FOWLER89) The most commonly used
arrangement is that of the coaxial FCG. The coaxial arrangement is of
particular interest in this context, as its essentially cylindrical form
factor lends itself to packaging into munitions.

  In a typical coaxial FCG , a cylindrical copper tube forms the armature.
This tube is filled with a fast high energy explosive. A number of explosive
types have been used, ranging from B and C-type compositions to machined
blocks of PBX-9501. The armature is surrounded by a helical coil of heavy
wire, typically copper, which forms the FCG stator. The stator winding is in
some designs split into segments, with wires bifurcating at the boundaries
of the segments, to optimise the electromagnetic inductance of the armature
coil.

  The intense magnetic forces produced during the operation of the FCG could
potentially cause the device to disintegrate prematurely if not dealt with.
This is typically accomplished by the addition of a structural jacket of a
non-magnetic material. Materials such as concrete or Fibreglass in an Epoxy
matrix have been used. In principle, any material with suitable electrical
and mechanical properties could be used. In applications where weight is an
issue, such as air delivered bombs or missile warheads, a glass or Kevlar
Epoxy composite would be a viable candidate.

  It is typical that the explosive is initiated when the start current
peaks. This is usually accomplished with a explosive lense plane wave
generator which produces a uniform plane wave burn (or detonation) front in
the explosive. Once initiated, the front propagates through the explosive in
the armature, distorting it into a conical shape (typically 12 to 14 degrees
of arc). Where the armature has expanded to the full diameter of the stator,
it forms a short circuit between the ends of the stator coil, shorting and
thus isolating the start current source and trapping the current within the
device. The propagating short has the effect of compressing the magnetic
field, whilst reducing the inductance of the stator winding. The result is
that such generators will producing a ramping current pulse, which peaks
before the final disintegration of the device. Published results suggest
ramp times of tens to hundreds of microseconds, specific to the
characteristics of the device, for peak currents of tens of MegaAmperes and
peak energies of tens of MegaJoules.

  The current multiplication (ie ratio of output current to start current)
achieved varies with designs, but numbers as high as 60 have been
demonstrated. In a munition application, where space and weight are at a
premium, the smallest possible start current source is desirable. These
applications can exploit cascading of FCGs, where a small FCG is used to
prime a larger FCG with a start current. Experiments conducted by LANL and
AFWL have demonstrated the viability of this technique [KIRTLAND94,
REINOVSKY85].

  The principal technical issues in adapting the FCG to weapons applications
lie in packaging, the supply of start current, and matching the device to
the intended load. Interfacing to a load is simplified by the coaxial
geometry of coaxial and conical FCG designs. Significantly, this geometry is
convenient for weapons applications, where FCGs may be stacked axially with
devices such a microwave Vircators. The demands of a load such as a
Vircator, in terms of waveform shape and timing, can be satisfied by
inserting pulse shaping networks, transformers and explosive high current
switches.

  3.2. Explosive and Propellant Driven MHD Generators
  The design of explosive and propellant driven Magneto-Hydrodynamic
generators is a much less mature art that that of FCG design. Technical
issues such as the size and weight of magnetic field generating devices
required for the operation of MHD generators suggest that MHD devices will
play a minor role in the near term. In the context of this paper, their
potential lies in areas such as start current generation for FCG devices.

  The fundamental principle behind the design of MHD devices is that a
conductor moving through a magnetic field will produce an electrical current
transverse to the direction of the field and the conductor motion. In an
explosive or propellant driven MHD device, the conductor is a plasma of
ionised explosive or propellant gas, which travels through the magnetic
field. Current is collected by electrodes which are in contact with the
plasma jet [FANTHOME89].

  The electrical properties of the plasma are optimised by seeding the
explosive or propellant with with suitable additives, which ionise during
the burn [FANTHOME89, FLANAGAN81]. Published experiments suggest that a
typical arrangement uses a solid propellant gas generator, often using
conventional ammunition propellant as a base. Cartridges of such propellant
can be loaded much like artillery rounds, for multiple shot operation.

  3.3. High Power Microwave Sources - The Vircator
  Whilst FCGs are potent technology base for the generation of large
electrical power pulses, the output of the FCG is by its basic physics
constrained to the frequency band below 1 MHz. Many target sets will be
difficult to attack even with very high power levels at such frequencies,
moreover focussing the energy output from such a device will be problematic.
A HPM device overcomes both of the problems, as its output power may be
tightly focussed and it has a much better ability to couple energy into many
target types.

  A wide range of HPM devices exist. Relativistic Klystrons, Magnetrons,
Slow Wave Devices, Reflex triodes, Spark Gap Devices and Vircators are all
examples of the available technology base [GRANATSTEIN87, HOEBERLING92].
From the perspective of a bomb or warhead designer, the device of choice
will be at this time the Vircator, or in the nearer term a Spark Gap source.
The Vircator is of interest because it is a one shot device capable of
producing a very powerful single pulse of radiation, yet it is mechanically
simple, small and robust, and can operate over a relatively broad band of
microwave frequencies.

  The physics of the Vircator tube are substantially more complex than those
of the preceding devices. The fundamental idea behind the Vircator is that
of accelerating a high current electron beam against a mesh (or foil) anode.
Many electrons will pass through the anode, forming a bubble of space charge
behind the anode. Under the proper conditions, this space charge region will
oscillate at microwave frequencies. If the space charge region is placed
into a resonant cavity which is appropriately tuned, very high peak powers
may be achieved. Conventional microwave engineering techniques may then be
used to extract microwave power from the resonant cavity. Because the
frequency of oscillation is dependent upon the electron beam parameters,
Vircators may be tuned or chirped in frequency, where the microwave cavity
will support appropriate modes. Power levels achieved in Vircator
experiments range from 170 kiloWatts to 40 GigaWatts over frequencies
spanning the decimetric and centimetric bands [THODE87].

  The two most commonly described configurations for the Vircator are the
Axial Vircator (AV) (Fig.3), and the Transverse Vircator (TV). The Axial
Vircator is the simplest by design, and has generally produced the best
power output in experiments. It is typically built into a cylindrical
waveguide structure. Power is most often extracted by transitioning the
waveguide into a conical horn structure, which functions as an antenna. AVs
typically oscillate in Transverse Magnetic (TM) modes. The Transverse
Vircator injects cathode current from the side of the cavity and will
typically oscillate in a Transverse Electric (TE) mode.

  Technical issues in Vircator design are output pulse duration, which is
typically of the order of a microsecond and is limited by anode melting,
stability of oscillation frequency, often compromised by cavity mode
hopping, conversion efficiency and total power output. Coupling power
efficiently from the Vircator cavity in modes suitable for a chosen antenna
type may also be an issue, given the high power levels involved and thus the
potential for electrical breakdown in insulators.

  4. The Lethality of Electromagnetic Warheads
  The issue of electromagnetic weapon lethality is complex. Unlike the
technology base for weapon construction, which has been widely published in
the open literature, lethality related issues have been published much less
frequently.

  While the calculation of electromagnetic field strengths achievable at a
given radius for a given device design is a straightforward task,
determining a kill probability for a given class of target under such
conditions is not.

  This is for good reasons. The first is that target types are very diverse
in their electromagnetic hardness, or ability to resist damage. Equipment
which has been intentionally shielded and hardened against electromagnetic
attack will withstand orders of magnitude greater field strengths than
standard commercially rated equipment. Moreover, various manufacturer's
implementations of like types of equipment may vary significantly in
hardness due the idiosyncrasies of specific electrical designs, cabling
schemes and chassis/shielding designs used.

  The second major problem area in determining lethality is that of coupling
efficiency, which is a measure of how much power is transferred from the
field produced by the weapon into the target. Only power coupled into the
target can cause useful damage.

  4.1. Coupling Modes
  In assessing how power is coupled into targets, two principal coupling
modes are recognised in the literature:

    a.. Front Door Coupling occurs typically when power from a
electromagnetic weapon is coupled into an antenna associated with radar or
communications equipment. The antenna subsystem is designed to couple power
in and out of the equipment, and thus provides an efficient path for the
power flow from the electromagnetic weapon to enter the equipment and cause
damage.
    b.. Back Door Coupling occurs when the electromagnetic field from a
weapon produces large transient currents (termed spikes, when produced by a
low frequency weapon ) or electrical standing waves (when produced by a HPM
weapon) on fixed electrical wiring and cables interconnecting equipment, or
providing connections to mains power or the telephone network [TAYLOR92,
WHITE78]. Equipment connected to exposed cables or wiring will experience
either high voltage transient spikes or standing waves which can damage
power supplies and communications interfaces if these are not hardened.
Moreover, should the transient penetrate into the equipment, damage can be
done to other devices inside.
  A low frequency weapon will couple well into a typical wiring
infrastructure, as most telephone lines, networking cables and power lines
follow streets, building risers and corridors. In most instances any
particular cable run will comprise multiple linear segments joined at
approximately right angles. Whatever the relative orientation of the weapons
field, more than one linear segment of the cable run is likely to be
oriented such that a good coupling efficiency can be achieved.

  It is worth noting at this point the safe operating envelopes of some
typical types of semiconductor devices. Manufacturer's guaranteed breakdown
voltage ratings for Silicon high frequency bipolar transistors, widely used
in communications equipment, typically vary between 15 V and 65 V. Gallium
Arsenide Field Effect Transistors are usually rated at about 10V. High
density Dynamic Random Access Memories (DRAM), an essential part of any
computer, are usually rated to 7 V against earth. Generic CMOS logic is
rated between 7 V and 15 V, and microprocessors running off 3.3 V or 5 V
power supplies are usually rated very closely to that voltage. Whilst many
modern devices are equipped with additional protection circuits at each pin,
to sink electrostatic discharges, sustained or repeated application of a
high voltage will often defeat these [MOTO3, MICRON92, NATSEMI86].

  Communications interfaces and power supplies must typically meet
electrical safety requirements imposed by regulators. Such interfaces are
usually protected by isolation transformers with ratings from hundreds of
Volts to about 2 to 3 kV [NPI93].

  It is clearly evident that once the defence provided by a transformer,
cable pulse arrestor or shielding is breached, voltages even as low as 50 V
can inflict substantial damage upon computer and communications equipment.
The author has seen a number of equipment items (computers, consumer
electronics) exposed to low frequency high voltage spikes (near lightning
strikes, electrical power transients), and in every instance the damage was
extensive, often requiring replacement of most semiconductors in the
equipment [2].

  HPM weapons operating in the centimetric and millimetric bands however
offer an additional coupling mechanism to Back Door Coupling. This is the
ability to directly couple into equipment through ventilation holes, gaps
between panels and poorly shielded interfaces. Under these conditions, any
aperture into the equipment behaves much like a slot in a microwave cavity,
allowing microwave radiation to directly excite or enter the cavity. The
microwave radiation will form a spatial standing wave pattern within the
equipment. Components situated within the anti-nodes within the standing
wave pattern will be exposed to potentially high electromagnetic fields.

  Because microwave weapons can couple more readily than low frequency
weapons, and can in many instances bypass protection devices designed to
stop low frequency coupling, microwave weapons have the potential to be
significantly more lethal than low frequency weapons.

  What research has been done in this area illustrates the difficulty in
producing workable models for predicting equipment vulnerability. It does
however provide a solid basis for shielding strategies and hardening of
equipment.

  The diversity of likely target types and the unknown geometrical layout
and electrical characteristics of the wiring and cabling infrastructure
surrounding a target makes the exact prediction of lethality impossible.

  A general approach for dealing with wiring and cabling related back door
coupling is to determine a known lethal voltage level, and then use this to
find the required field strength to generate this voltage. Once the field
strength is known, the lethal radius for a given weapon configuration can be
calculated.

  A trivial example is that of a 10 GW 5 GHz HPM device illuminating a
footprint of 400 to 500 metres diameter, from a distance of several hundred
metres. This will result in field strengths of several kiloVolts per metre
within the device footprint, in turn capable of producing voltages of
hundreds of volts to kiloVolts on exposed wires or cables [KRAUS88,
TAYLOR92]. This suggests lethal radii of the order of hundreds of metres,
subject to weapon performance and target set electrical hardness.

  4.2. Maximising Electromagnetic Bomb Lethality
  To maximise the lethality of an electromagnetic bomb it is necessary to
maximise the power coupled into the target set.

  The first step in maximising bomb lethality is is to maximise the peak
power and duration of the radiation of the weapon. For a given bomb size,
this is accomplished by using the most powerful flux compression generator
(and Vircator in a HPM bomb) which will fit the weapon size, and by
maximising the efficiency of internal power transfers in the weapon. Energy
which is not emitted is energy wasted at the expense of lethality.

  The second step is to maximise the coupling efficiency into the target
set. A good strategy for dealing with a complex and diverse target set is to
exploit every coupling opportunity available within the bandwidth of the
weapon.

  A low frequency bomb built around an FCG will require a large antenna to
provide good coupling of power from the weapon into the surrounding
environment. Whilst weapons built this way are inherently wide band, as most
of the power produced lies in the frequency band below 1 MHz compact
antennas are not an option. One possible scheme is for a bomb approaching
its programmed firing altitude to deploy five linear antenna elements. These
are produced by firing off cable spools which unwind several hundred metres
of cable. Four radial antenna elements form a "virtual" earth plane around
the bomb, while an axial antenna element is used to radiate the power from
the FCG. The choice of element lengths would need to be carefully matched to
the frequency characteristics of the weapon, to produce the desired field
strength. A high power coupling pulse transformer is used to match the low
impedance FCG output to the much higher impedance of the antenna, and ensure
that the current pulse does not vapourise the cable prematurely.

  Other alternatives are possible. One is to simply guide the bomb very
close to the target, and rely upon the near field produced by the FCG
winding, which is in effect a loop antenna of very small diameter relative
to the wavelength. Whilst coupling efficiency is inherently poor, the use of
a guided bomb would allow the warhead to be positioned accurately within
metres of a target. An area worth further investigation in this context is
the use of low frequency bombs to damage or destroy magnetic tape libraries,
as the near fields in the vicinity of a flux generator are of the order of
magnitude of the coercivity of most modern magnetic materials.

  Microwave bombs have a broader range of coupling modes and given the small
wavelength in comparison with bomb dimensions, can be readily focussed
against targets with a compact antenna assembly. Assuming that the antenna
provides the required weapon footprint, there are at least two mechanisms
which can be employed to further maximise lethality.

  The first is sweeping the frequency or chirping the Vircator. This can
improve coupling efficiency in comparison with a single frequency weapon, by
enabling the radiation to couple into apertures and resonances over a range
of frequencies. In this fashion, a larger number of coupling opportunities
are exploited.

  The second mechanism which can be exploited to improve coupling is the
polarisation of the weapon's emission. If we assume that the orientations of
possible coupling apertures and resonances in the target set are random in
relation to the weapon's antenna orientation, a linearly polarised emission
will only exploit half of the opportunities available. A circularly
polarised emission will exploit all coupling opportunities.

  The practical constraint is that it may be difficult to produce an
efficient high power circularly polarised antenna design which is compact
and performs over a wide band. Some work therefore needs to be done on
tapered helix or conical spiral type antennas capable of handling high power
levels, and a suitable interface to a Vircator with multiple extraction
ports must devised. A possible implementation is depicted in Fig.5. In this
arrangement, power is coupled from the tube by stubs which directly feed a
multi-filar conical helix antenna. An implementation of this scheme would
need to address the specific requirements of bandwidth, beamwidth,
efficiency of coupling from the tube, while delivering circularly polarised
radiation.

  Another aspect of electromagnetic bomb lethality is its detonation
altitude, and by varying the detonation altitude, a tradeoff may be achieved
between the size of the lethal footprint and the intensity of the
electromagnetic field in that footprint. This provides the option of
sacrificing weapon coverage to achieve kills against targets of greater
electromagnetic hardness, for a given bomb size (Fig.7, 8). This is not
unlike the use of airburst explosive devices.

  In summary, lethality is maximised by maximising power output and the
efficiency of energy transfer from the weapon to the target set. Microwave
weapons offer the ability to focus nearly all of their energy output into
the lethal footprint, and offer the ability to exploit a wider range of
coupling modes. Therefore, microwave bombs are the preferred choice.

  5. Targeting Electromagnetic Bombs
  The task of identifying targets for attack with electromagnetic bombs can
be complex. Certain categories of target will be very easy to identify and
engage. Buildings housing government offices and thus computer equipment,
production facilities, military bases and known radar sites and
communications nodes are all targets which can be readily identified through
conventional photographic, satellite, imaging radar, electronic
reconnaissance and humint operations. These targets are typically
geographically fixed and thus may be attacked providing that the aircraft
can penetrate to weapon release range. With the accuracy inherent in
GPS/inertially guided weapons, the electromagnetic bomb can be programmed to
detonate at the optimal position to inflict a maximum of electrical damage.

  Mobile and camouflaged targets which radiate overtly can also be readily
engaged. Mobile and relocatable air defence equipment, mobile communications
nodes and naval vessels are all good examples of this category of target.
While radiating, their positions can be precisely tracked with suitable
Electronic Support Measures (ESM) and Emitter Locating Systems (ELS) carried
either by the launch platform or a remote surveillance platform. In the
latter instance target coordinates can be continuously datalinked to the
launch platform. As most such targets move relatively slowly, they are
unlikely to escape the footprint of the electromagnetic bomb during the
weapon's flight time.

  Mobile or hidden targets which do not overtly radiate may present a
problem, particularly should conventional means of targeting be employed. A
technical solution to this problem does however exist, for many types of
target. This solution is the detection and tracking of Unintentional
Emission (UE) [HERSKOWITZ96]. UE has attracted most attention in the context
of TEMPEST [3] surveillance, where transient emanations leaking out from
equipment due poor shielding can be detected and in many instances
demodulated to recover useful intelligence. Termed Van Eck radiation
[VECK85], such emissions can only be suppressed by rigorous shielding and
emission control techniques, such as are employed in TEMPEST rated
equipment.

  Whilst the demodulation of UE can be a technically difficult task to
perform well, in the context of targeting electromagnetic bombs this problem
does not arise. To target such an emitter for attack requires only the
ability to identify the type of emission and thus target type, and to
isolate its position with sufficient accuracy to deliver the bomb. Because
the emissions from computer monitors, peripherals, processor equipment,
switchmode power supplies, electrical motors, internal combustion engine
ignition systems, variable duty cycle electrical power controllers
(thyristor or triac based), superheterodyne receiver local oscillators and
computer networking cables are all distinct in their frequencies and
modulations, a suitable Emitter Locating System can be designed to detect,
identify and track such sources of emission.

  A good precedent for this targeting paradigm exists. During the SEA
(Vietnam) conflict the United States Air Force (USAF) operated a number of
night interdiction gunships which used direction finding receivers to track
the emissions from vehicle ignition systems. Once a truck was identified and
tracked, the gunship would engage it [4].

  Because UE occurs at relatively low power levels, the use of this
detection method prior to the outbreak of hostilities can be difficult, as
it may be necessary to overfly hostile territory to find signals of usable
intensity [5]. The use of stealthy reconnaissance aircraft or long range,
stealthy Unmanned Aerial Vehicles (UAV) may be required. The latter also
raises the possibility of autonomous electromagnetic warhead armed
expendable UAVs, fitted with appropriate homing receivers. These would be
programmed to loiter in a target area until a suitable emitter is detected,
upon which the UAV would home in and expend itself against the target.

  6. The Delivery of Conventional Electromagnetic Bombs
  As with explosive warheads, electromagnetic warheads will occupy a volume
of physical space and will also have some given mass (weight) determined by
the density of the internal hardware. Like explosive warheads,
electromagnetic warheads may be fitted to a range of delivery vehicles.

  Known existing applications [6] involve fitting an electromagnetic warhead
to a cruise missile airframe. The choice of a cruise missile airframe will
restrict the weight of the weapon to about 340 kg (750 lb), although some
sacrifice in airframe fuel capacity could see this size increased. A
limitation in all such applications is the need to carry an electrical
energy storage device, eg a battery, to provide the current used to charge
the capacitors used to prime the FCG prior to its discharge. Therefore the
available payload capacity will be split between the electrical storage and
the weapon itself.

  In wholly autonomous weapons such as cruise missiles, the size of the
priming current source and its battery may well impose important limitations
on weapon capability. Air delivered bombs, which have a flight time between
tens of seconds to minutes, could be built to exploit the launch aircraft's
power systems. In such a bomb design, the bomb's capacitor bank can be
charged by the launch aircraft enroute to target, and after release a much
smaller onboard power supply could be used to maintain the charge in the
priming source prior to weapon initiation.

  An electromagnetic bomb delivered by a conventional aircraft [7] can offer
a much better ratio of electromagnetic device mass to total bomb mass, as
most of the bomb mass can be dedicated to the electromagnetic device
installation itself. It follows therefore, that for a given technology an
electromagnetic bomb of identical mass to a electromagnetic warhead equipped
missile can have a much greater lethality, assuming equal accuracy of
delivery and technologically similar electromagnetic device design.

  A missile borne electromagnetic warhead installation will comprise the
electromagnetic device, an electrical energy converter, and an onboard
storage device such as a battery. As the weapon is pumped, the battery is
drained. The electromagnetic device will be detonated by the missile's
onboard fusing system. In a cruise missile, this will be tied to the
navigation system; in an anti-shipping missile the radar seeker and in an
air-to-air missile, the proximity fusing system. The warhead fraction (ie
ratio of total payload (warhead) mass to launch mass of the weapon) will be
between 15% and 30% [8].

  An electromagnetic bomb warhead will comprise an electromagnetic device,
an electrical energy converter and a energy storage device to pump and
sustain the electromagnetic device charge after separation from the delivery
platform. Fusing could be provided by a radar altimeter fuse to airburst the
bomb, a barometric fuse or in GPS/inertially guided bombs, the navigation
system. The warhead fraction could be as high as 85%, with most of the
usable mass occupied by the electromagnetic device and its supporting
hardware.

  Due to the potentially large lethal radius of an electromagnetic device,
compared to an explosive device of similar mass, standoff delivery would be
prudent. Whilst this is an inherent characteristic of weapons such as cruise
missiles, potential applications of these devices to glidebombs,
anti-shipping missiles and air-to-air missiles would dictate fire and forget
guidance of the appropriate variety, to allow the launching aircraft to gain
adequate separation of several miles before warhead detonation.

  The recent advent of GPS satellite navigation guidance kits for
conventional bombs and glidebombs has provided the optimal means for cheaply
delivering such weapons. While GPS guided weapons without differential GPS
enhancements may lack the pinpoint accuracy of laser or television guided
munitions, they are still quite accurate (CEP \(~~ 40 ft) and importantly,
cheap, autonomous all weather weapons.

  The USAF has recently deployed the Northrop GAM (GPS Aided Munition) on
the B-2 bomber [NORTHROP95], and will by the end of the decade deploy the
GPS/inertially guided GBU-29/30 JDAM (Joint Direct Attack Munition)[MDC95]
and the AGM-154 JSOW (Joint Stand Off Weapon) [PERGLER94] glidebomb. Other
countries are also developing this technology, the Australian BAeA AGW
(Agile Glide Weapon) glidebomb achieving a glide range of about 140 km (75
nmi) when launched from altitude [KOPP96].

  The importance of glidebombs as delivery means for HPM warheads is
threefold. Firstly, the glidebomb can be released from outside effective
radius of target air defences, therefore minimising the risk to the launch
aircraft. Secondly, the large standoff range means that the aircraft can
remain well clear of the bomb's effects. Finally the bomb's autopilot may be
programmed to shape the terminal trajectory of the weapon, such that a
target may be engaged from the most suitable altitude and aspect.

  A major advantage of using electromagnetic bombs is that they may be
delivered by any tactical aircraft with a nav-attack system capable of
delivering GPS guided munitions. As we can expect GPS guided munitions to be
become the standard weapon in use by Western air forces by the end of this
decade, every aircraft capable of delivering a standard guided munition also
becomes a potential delivery vehicle for a electromagnetic bomb. Should
weapon ballistic properties be identical to the standard weapon, no software
changes to the aircraft would be required.

  Because of the simplicity of electromagnetic bombs in comparison with
weapons such as Anti Radiation Missiles (ARM), it is not unreasonable to
expect that these should be both cheaper to manufacture, and easier to
support in the field, thus allowing for more substantial weapon stocks. In
turn this makes saturation attacks a much more viable proposition.

  In this context it is worth noting that the USAF's possesion of the JDAM
capable F-117A and B-2A will provide the capability to deliver E-bombs
against arbitrary high value targets with virtual impunity. The ability of a
B-2A to deliver up to sixteen GAM/JDAM fitted E-bomb warheads with a 20 ft
class CEP would allow a small number of such aircraft to deliver a decisive
blow against key strategic, air defence and theatre targets. A strike and
electronic combat capable derivative of the F-22 would also be a viable
delivery platform for an E-bomb/JDAM. With its superb radius, low signature
and supersonic cruise capability an RFB-22 could attack air defence sites,
C3I sites, airbases and strategic targets with E-bombs, achieving a
significant shock effect. A good case may be argued for the whole F-22 build
to be JDAM/E-bomb capable, as this would allow the USAF to apply the maximum
concentration of force against arbitrary air and surface targets during the
opening phase of an air campaign.

  7. Defence Against Electromagnetic Bombs
  The most effective defence against electromagnetic bombs is to prevent
their delivery by destroying the launch platform or delivery vehicle, as is
the case with nuclear weapons. This however may not always be possible, and
therefore systems which can be expected to suffer exposure to the
electromagnetic weapons effects must be electromagnetically hardened.

  The most effective method is to wholly contain the equipment in an electri
cally conductive enclosure, termed a Faraday cage, which prevents the
electromagnetic field from gaining access to the protected equipment.
However, most such equipment must communicate with and be fed with power
from the outside world, and this can provide entry points via which
electrical transients may enter the enclosure and effect damage. While
optical fibres address this requirement for transferring data in and out,
electrical power feeds remain an ongoing vulnerability.

  Where an electrically conductive channel must enter the enclosure,
electromagnetic arresting devices must be fitted. A range of devices exist,
however care must be taken in determining their parameters to ensure that
they can deal with the rise time and strength of electrical transients
produced by electromagnetic devices. Reports from the US [9] indicate that
hardening measures attuned to the behaviour of nuclear EMP bombs do not
perform well when dealing with some conventional microwave electromagnetic
device designs.

  It is significant that hardening of systems must be carried out at a
system level, as electromagnetic damage to any single element of a complex
system could inhibit the function of the whole system. Hardening new build
equipment and systems will add a substantial cost burden. Older equipment
and systems may be impossible to harden properly and may require complete
replacement. In simple terms, hardening by design is significantly easier
than attempting to harden existing equipment.

  An interesting aspect of electrical damage to targets is the possibility
of wounding semiconductor devices thereby causing equipment to suffer
repetitive intermittent faults rather than complete failures. Such faults
would tie down considerable maintenance resources while also diminishing the
confidence of the operators in the equipment's reliability. Intermittent
faults may not be possible to repair economically, thereby causing equipment
in this state to be removed from service permanently, with considerable loss
in maintenance hours during damage diagnosis. This factor must also be
considered when assessing the hardness of equipment against electromagnetic
attack, as partial or incomplete hardening may in this fashion cause more
difficulties than it would solve. Indeed, shielding which is incomplete may
resonate when excited by radiation and thus contribute to damage inflicted
upon the equipment contained within it.

  Other than hardening against attack, facilities which are concealed should
not radiate readily detectable emissions. Where radio frequency
communications must be used, low probability of intercept (ie spread
spectrum) techniques should be employed exclusively to preclude the use of
site emissions for electromagnetic targeting purposes [DIXON84]. Appropriate
suppression of UE is also mandatory.

  Communications networks for voice, data and services should employ
topologies with sufficient redundancy and failover mechanisms to allow
operation with multiple nodes and links inoperative. This will deny a user
of electromagnetic bombs the option of disabling large portions if not the
whole of the network by taking down one or more key nodes or links with a
single or small number of attacks.

  8. Limitations of Electromagnetic Bombs
  The limitations of electromagnetic weapons are determined by weapon
implementation and means of delivery. Weapon implementation will determine
the electromagnetic field strength achievable at a given radius, and its
spectral distribution. Means of delivery will constrain the accuracy with
which the weapon can be positioned in relation to the intended target. Both
constrain lethality.

  In the context of targeting military equipment, it must be noted that
thermionic technology (ie vacuum tube equipment) is substantially more
resilient to the electromagnetic weapons effects than solid state (ie
transistor) technology. Therefore a weapon optimised to destroy solid state
computers and receivers may cause little or no damage to a thermionic
technology device, for instance early 1960s Soviet military equipment.
Therefore a hard electrical kill may not be achieved against such targets
unless a suitable weapon is used.

  This underscores another limitation of electromagnetic weapons, which is
the difficulty in kill assessment. Radiating targets such as radars or
communications equipment may continue to radiate after an attack even though
their receivers and data processing systems have been damaged or destroyed.
This means that equipment which has been successfully attacked may still
appear to operate. Conversely an opponent may shut down an emitter if attack
is imminent and the absence of emissions means that the success or failure
of the attack may not be immediately apparent.

  Assessing whether an attack on a non radiating emitter has been successful
is more problematic. A good case can be made for developing tools
specifically for the purpose of analysing unintended emissions, not only for
targeting purposes, but also for kill assessment.

  An important factor in assessing the lethal coverage of an electromagnetic
weapon is atmospheric propagation. While the relationship between
electromagnetic field strength and distance from the weapon is one of an
inverse square law in free space, the decay in lethal effect with increasing
distance within the atmosphere will be greater due quantum physical
absorption effects [10]. This is particularly so at higher frequencies, and
significant absorption peaks due water vapour and oxygen exist at
frequencies above 20 GHz. These will therefore contain the effect of HPM
weapons to shorter radii than are ideally achievable in the K and L
frequency bands.

  Means of delivery will limit the lethality of an electromagnetic bomb by
introducing limits to the weapon's size and the accuracy of its delivery.
Should the delivery error be of the order of the weapon's lethal radius for
a given detonation altitude, lethality will be significantly diminished.
This is of particular importance when assessing the lethality of unguided
electromagnetic bombs, as delivery errors will be more substantial than
those experienced with guided weapons such as GPS guided bombs.

  Therefore accuracy of delivery and achievable lethal radius must be
considered against the allowable collateral damage for the chosen target.
Where collateral electrical damage is a consideration, accuracy of delivery
and lethal radius are key parameters. An inaccurately delivered weapon of
large lethal radius may be unusable against a target should the likely
collateral electrical damage be beyond acceptable limits. This can be a
major issue for users constrained by treaty provisions on collateral damage
[AAP1003].

  9. The Proliferation of Electromagnetic Bombs
  At the time of writing, the United States and the CIS are the only two
nations with the established technology base and the depth of specific
experience to design weapons based upon this technology. However, the
relative simplicity of the FCG and the Vircator suggests that any nation
with even a 1940s technology base, once in possession of engineering
drawings and specifications for such weapons, could manufacture them.

  As an example, the fabrication of an effective FCG can be accomplished
with basic electrical materials, common plastic explosives such as C-4 or
Semtex, and readily available machine tools such as lathes and suitable
mandrels for forming coils. Disregarding the overheads of design, which do
not apply in this context, a two stage FCG could be fabricated for a cost as
low as $1,000-2,000, at Western labour rates [REINOVSKY85]. This cost could
be even lower in a Third World or newly industrialised economy.

  While the relative simplicity and thus low cost of such weapons can be
considered of benefit to First World nations intending to build viable war
stocks or maintain production in wartime, the possibility of less developed
nations mass producing such weapons is alarming. The dependence of modern
economies upon their information technology infrastructure makes them highly
vulnerable to attack with such weapons, providing that these can be
delivered to their targets.

  Of major concern is the vulnerability resulting from increasing use of
communications and data communications schemes based upon copper cable
media. If the copper medium were to be replaced en masse with optical fibre
in order to achieve higher bandwidths, the communications infrastructure
would become significantly more robust against electromagnetic attack as a
result. However, the current trend is to exploit existing distribution media
such as cable TV and telephone wiring to provide multiple Megabit/s data
distribution (eg cable modems, ADSL/HDSL/VDSL) to premises. Moreover, the
gradual replacement of coaxial Ethernet networking with 10-Base-T twisted
pair equipment has further increased the vulnerability of wiring systems
inside buildings. It is not unreasonable to assume that the data and
services communications infrastructure in the West will remain a "soft"
electromagnetic target in the forseeable future.

  At this time no counter-proliferation regimes exist. Should treaties be
agreed to limit the proliferation of electromagnetic weapons, they would be
virtually impossible to enforce given the common availability of suitable
materials and tools.

  With the former CIS suffering significant economic difficulties, the
possibility of CIS designed microwave and pulse power technology leaking out
to Third World nations or terrorist organisations should not be discounted.
The threat of electromagnetic bomb proliferation is very real.

  10. A Doctrine for the Use of Conventional Electromagnetic Bombs
  A fundamental tenet of IW is that complex organisational systems such as
governments, industries and military forces cannot function without the flow
of information through their structures. Information flows within these
structures in several directions, under typical conditions of function. A
trivial model for this function would see commands and directives flowing
outward from a central decisionmaking element, with information about the
state of the system flowing in the opposite direction. Real systems are
substantially more complex.

  This is of military significance because stopping this flow of information
will severely debilitate the function of any such system. Stopping the
outward flow of information produces paralysis, as commands cannot reach the
elements which are to execute them. Stopping the inward flow of information
isolates the decisionmaking element from reality, and thus severely inhibits
its capacity to make rational decisions which are sensitive to the currency
of information at hand.

  The recent evolution of strategic (air) warfare indicates a growing trend
toward targeting strategies which exploit this most fundamental
vulnerability of any large and organised system [11]. The Desert Storm air
war of 1991 is a good instance, with a substantial effort expended against
such targets. Indeed, the model used for modern strategic air attack places
leadership and its supporting communications in the position of highest
targeting priority [WARDEN95]. No less importantly, modern Electronic Combat
concentrates upon the disruption and destruction of communications and
information gathering sensors used to support military operations. Again the
Desert Storm air war provides a good illustration of the application of this
method.

  A strategy which stresses attack upon the information processing and
communications elements of the systems which it is targeting offers a very
high payoff, as it will introduce an increasing level of paralysis and
disorientation within its target. Electromagnetic bombs are a powerful tool
in the implementation of such a strategy.

  10.1 Electronic Combat Operations using Electromagnetic Bombs
  The central objective of Electronic Combat (EC) operations is the command
of the electromagnetic spectrum, achieved by soft and hard kill means [12]
against the opponent's electronic assets. The underlying objective of
commanding the electromagnetic spectrum is to interrupt or substantially
reduce the flow of information through the opponent's air defence system,
air operations environment and between functional elements of weapon
systems.

  In this context the ability of electromagnetic bombs to achieve kills
against a wide range of target types allows their general application to the
task of inflicting attrition upon an opponent's electronic assets, be they
specialised air defence assets or more general
Command-Control-Communications (C3) and other military assets.

  Electromagnetic bombs can be a means of both soft and hard electrical
kill, subject to the lethality of the weapon and the hardness of its target.
A hard electrical kill by means of an electromagnetic device will be
achieved in those instances where such severe electrical damage is achieved
against a target so as to require the replacement of most if not all of its
internal electronics.

  Electronic combat operations using electromagnetic devices involve the use
of these to attack radar, C3 and air defence weapon systems. These should
always be attacked initially with an electromagnetic weapon to achieve soft
or hard electrical kills, followed up by attack with conventional munitions
to preclude possible repair of disabled assets at a later time. As with
conventional SEAD operations, the greatest payoff will be achieved by using
electromagnetic weapons against systems of strategic importance first,
followed in turn by those of operational and tactical importance [KOPP92].

  In comparison with an AntiRadiation Missile (ARM - a missile which homes
on the emissions from a threat radar), the established and specialised tool
in the conduct of SEAD operations, an electromagnetic bomb can achieve kills
against multiple targets of diverse types within its lethal footprint. In
this respect an electromagnetic device may be described as a Weapon of
Electrical Mass Destruction (WEMD). Therefore electromagnetic weapons are a
significant force multiplier in electronic combat operations.

  A conventional electronic combat campaign, or intensive electronic combat
operations, will initially concentrate on saturating the opponent's
electronic defences, denying information and inflicting maximum attrition
upon electronic assets. The force multiplication offered by electromagnetic
weapons vastly reduces the number of air assets required to inflict
substantial attrition, and where proper electronic reconnaissance has been
carried out beforehand, also reduces the need for specialised assets such as
ARM firing aircraft equipped with costly emitter locating systems.

  The massed application of electromagnetic bombs in the opening phase of an
electronic battle will allow much faster attainment of command of the
electromagnetic spectrum, as it will inflict attrition upon electronic
assets at a much faster rate than possible with conventional means.

  Whilst the immaturity of conventional electromagnetic weapons precludes an
exact analysis of the scale of force multiplication achievable, it is
evident that a single aircraft carrying an electromagnetic bomb capable of
concurrently disabling a SAM site with its colocated acquisition radar and
supporting radar directed AAA weapons, will have the potency of the several
ARM firing and support jamming aircraft required to accomplish the same
result by conventional means. This and the ability of multirole tactical
aircraft to perform this task allows for a much greater concentration of
force in the opening phase of the battle, for a given force size.

  In summary the massed application of electromagnetic weapons to Electronic
Combat operations will provide for a much faster rate of attrition against
hostile electronic assets, achievable with a significantly reduced number of
specialised and multirole air assets [13]. This will allow even a modestly
sized force to apply overwhelming pressure in the initial phase of an
electronic battle, and therefore achieve command of the electromagnetic
spectrum in a significantly shorter time than by conventional means.

  10.2. Strategic Air Attack Operations using Electromagnetic Bombs
  The modern approach to strategic air warfare reflects in many respects
aspects of the IW model, in that much effort is expended in disabling an
opponent's fundamental information processing infrastructure. Since we
however are yet to see a systematic IW doctrine which has been tested in
combat, this paper will approach the subject from a more conservative
viewpoint and use established strategic doctrine.

  Modern strategic air attack theory is based upon Warden's Five Rings model
[WARDEN95], which identifies five centres of gravity in a nation's
warfighting capability. In descending order of importance, these are the
nation's leadership and supporting C3 system, its essential economic
infrastructure, its transportation network, its population and its fielded
military forces.

  Electromagnetic weapons may be productively used against all elements in
this model, and provide a particularly high payoff when applied against a
highly industrialised and geographically concentrated opponent. Of
particular importance in the context of strategic air attack, is that while
electromagnetic weapons are lethal to electronics, they have little if any
effect on humans. This is a characteristic which is not shared with
established conventional and nuclear weapons.

  This selectivity in lethal effect makes electromagnetic weapons far more
readily applicable to a strategic air attack campaign, and reduces the
internal political pressure which is experienced by the leadership of any
democracy which must commit to warfare. An opponent may be rendered
militarily, politically and economically ineffective with little if any loss
in human life.

  The innermost ring in the Warden model essentially comprises government
bureaucracies and civilian and military C3 systems. In any modern nation
these are heavily dependent upon the use of computer equipment and
communications equipment. What is of key importance at this time is an
ongoing change in the structure of computing facilities used in such
applications, as these are becoming increasingly decentralised. A modern
office environment relies upon a large number of small computers, networked
to interchange information, in which respect it differs from the traditional
model of using a small number of powerful central machines.

  This decentralisation and networking of information technology systems
produces a major vulnerability to electromagnetic attack. Whereas a small
number of larger computers could be defended against electromagnetic attack
by the use of electromagnetic hardened computer rooms, a large distributed
network cannot. Moreover, unless optical fibre networking is used, the
networking cables are themselves a medium via which electromagnetic effects
can be efficiently propagated throughout the network, to destroy machines.
Whilst the use of distributed computer networks reduces vulnerability to
attack by conventional munitions, it increases vulnerability to attack by
electromagnetic weapons.

  Selective targeting of government buildings with electromagnetic weapons
will result in a substantial reduction in a government's ability to handle
and process information. The damage inflicted upon information records may
be permanent, should inappropriate backup strategies have been used to
protect stored data. It is reasonable to expect most data stored on machines
which are affected will perish with the host machine, or become extremely
difficult to recover from damaged storage devices.

  The cost of hardening existing computer networks is prohibitive, as is the
cost of replacement with hardened equipment. Whilst the use of hardened
equipment for critical tasks would provide some measure of resilience, the
required discipline in the handling of information required to implement
such a scheme renders its utility outside of military organisations
questionable. Therefore the use of electromagnetic weapons against
government facilities offers an exceptionally high payoff.

  Other targets which fall into the innermost ring may also be profitably
attacked. Satellite link and importantly control facilities are vital means
of communication as well as the primary interface to military and commercial
reconnaissance satellites. Television and radio broadcasting stations, one
of the most powerful tools of any government, are also vulnerable to
electromagnetic attack due the very high concentration of electronic
equipment in such sites. Telephone exchanges, particularly later generation
digital switching systems, are also highly vulnerable to appropriate
electromagnetic attack.

  In summary the use of electromagnetic weapons against leadership and C3
targets is highly profitable, in that a modest number of weapons
appropriately used can introduce the sought state of strategic paralysis,
without the substantial costs incurred by the use of conventional munitions
to achieve the same effect.

  Essential economic infrastructure is also vulnerable to electromagnetic
attack. The finance industry and stock markets are almost wholly dependent
upon computers and their supporting communications. Manufacturing, chemical,
petroleum product industries and metallurgical industries rely heavily upon
automation which is almost universally implemented with electronic PLC
(Programmable Logic Controller) systems or digital computers. Furthermore,
most sensors and telemetry devices used are electrical or electronic.

  Attacking such economic targets with electromagnetic weapons will halt
operations for the time required to either repair the destroyed equipment,
or to reconfigure for manual operation. Some production processes however
require automated operation, either because hazardous conditions prevent
human intervention, or the complexity of the control process required cannot
be carried out by a human operator in real time. A good instance are larger
chemical, petrochemical and oil/gas production facilities. Destroying
automated control facilities will therefore result in substantial loss of
production, causing shortages of these vital materials.

  Manufacturing industries which rely heavily upon robotic and semiautomatic
machinery, such as the electronics, computer and electrical industry,
precision machine industry and aerospace industries, are all key assets in
supporting a military capability. They are all highly vulnerable to
electromagnetic attack. Whilst material processing industries may in some
instances be capable of function with manual process control, the
manufacturing industries are almost wholly dependent upon their automated
machines to achieve any useful production output.

  Historical experience [14] suggests that manufacturing industries are
highly resilient to air attack as production machinery is inherently
mechanically robust and thus a very high blast overpressure is required to
destroy it. The proliferation of electronic and computer controlled
machinery has produced a major vulnerability, for which historical precedent
does not exist. Therefore it will be necessary to reevaluate this orthodoxy
in targeting strategy.

  The finance industry and stock markets are a special case in this context,
as the destruction of their electronic infrastructure can yield, unlike
manufacturing industries, much faster economic dislocation. This can in turn
produce large systemic effects across a whole economy, including elements
which are not vulnerable to direct electromagnetic attack. This may be of
particular relevance when dealing with an opponent which does not have a
large and thus vulnerable manufacturing economy. Nations which rely on
agriculture, mining or trade for a large proportion of the their gross
domestic product are prime candidates for electromagnetic attack on their
finance industry and stock markets. Since the latter are usually
geographically concentrated and typically electromagnetically "soft"
targets, they are highly vulnerable.

  In summary there is a large payoff in striking at economic essentials with
electromagnetic weapons, particularly in the opening phase of a strategic
air attack campaign, as economic activity may be halted or reduced with
modest expenditure of the attacker's resources. An important caveat is that
centres of gravity within the target economy must be properly identified and
prioritised for strikes to ensure that maximum effect is achieved as quickly
as possible.

  Transport infrastructure is the third ring in the Warden model, and also
offers some useful opportunities for the application of electromagnetic
weapons. Unlike the innermost rings, the concentration of electronic and
computer equipment is typically much lower, and therefore considerable care
must be taken in the selection of targets.

  Railway and road signalling systems, where automated, are most vulnerable
to electromagnetic attack on their control centres. This could be used to
produce traffic congestion by preventing the proper scheduling of rail
traffic, and disabling road traffic signalling, although the latter may not
yield particularly useful results.

  Significantly, most modern automobiles and trucks use electronic ignition
systems which are known to be vulnerable to electromagnetic weapons effects,
although opportunities to find such concentrations so as to allow the
profitable use of an electromagnetic bomb may be scarce.

  The population of the target nation is the fourth ring in the Warden
model, and its morale is the object of attack. The morale of the population
will be affected significantly by the quality and quantity of the government
propaganda it is subjected to, as will it be affected by living conditions.

  Using electromagnetic weapons against urban areas provides the opportunity
to prevent government propaganda from reaching the population via means of
mass media, through the damaging or destruction of all television and radio
receivers within the footprint of the weapon. Whether this is necessary,
given that broadcast facilities may have already been destroyed, is open to
discussion. Arguably it may be counterproductive, as it will prevent the
target population from being subjected to friendly means of psychological
warfare such as propaganda broadcasts.

  The use of electromagnetic weapons against a target population is
therefore an area which requires requires careful consideration in the
context of the overall IW campaign strategy. If useful objectives can be
achieved by isolating the population from government propaganda, then the
population is a valid target for electromagnetic attack. Forces constrained
by treaty obligations will have to reconcile this against the applicable
regulations relating to denial of services to non-combatants [AAP1003].

  The outermost and last ring in the Warden model are the fielded military
forces. These are by all means a target vulnerable to electromagnetic
attack, and C3 nodes, fixed support bases as well as deployed forces should
be attacked with electromagnetic devices. Fixed support bases which carry
out depot level maintenance on military equipment offer a substantial
payoff, as the concentration of computers in both automatic test equipment
and administrative and logistic support functions offers a good return per
expended weapon.

  Any site where more complex military equipment is concentrated should be
attacked with electromagnetic weapons to render the equipment unservicable
and hence reduce the fighting capability, and where possible also mobility
of the targeted force. As discussed earlier in the context of Electronic
Combat, the ability of an electromagnetic weapon to achieve hard electrical
kills against any non-hardened targets within its lethal footprint suggests
that some target sites may only require electromagnetic attack to render
them both undefended and non-operational. Whether to expend conventional
munitions on targets in this state would depend on the immediate military
situation.

  In summary the use of electromagnetic weapons in strategic air attack
campaign offers a potentially high payoff, particularly when applied to
leadership, C3 and vital economic targets, all of which may be deprived of
much of their function for substantial periods of time. The massed
application of electromagnetic weapons in the opening phase of the campaign
would introduce paralysis within the government, deprived of much of its
information processing infrastructure, as well as paralysis in most vital
industries. This would greatly reduce the capability of the target nation to
conduct military operations of any substantial intensity.

  Because conventional electromagnetic weapons produce negligible collateral
damage, in comparison with conventional explosive munitions, they allow the
conduct of an effective and high tempo campaign without the loss of life
which is typical of conventional campaigns. This will make the option of a
strategic bombing campaign more attractive to a Western democracy, where
mass media coverage of the results of conventional strategic strike
operations will adversely affect domestic civilian morale.

  The long term effects of a sustained and concentrated strategic bombing
campaign using a combination of conventional and electromagnetic weapons
will be important. The cost of computer and communications infrastructure is
substantial, and its massed destruction would be a major economic burden for
any industrialised nation. In addition it is likely that poor protection of
stored data will add to further economic losses, as much data will be lost
with the destroyed machines.

  From the perspective of conducting an IW campaign, this method of attack
achieves many of the central objectives sought. Importantly, the massed
application of electromagnetic weapons would inflict attrition on an
opponent's information processing infrastructure very rapidly, and this
would arguably add a further psychological dimension to the potency of the
attack. Unlike the classical IW model of Gibsonian CyberWar, in which the
opponent can arguably isolate his infrastructure from hostile penetration,
parallel or hyperwar style massed attack with electromagnetic bombs will be
be extremely difficult to defend against.

  10.3. Offensive Counter Air (OCA) Operations using Electromagnetic Bombs
  Electromagnetic bombs may be usefully applied to OCA operations. Modern
aircraft are densely packed with electronics, and unless properly hardened,
are highly vulnerable targets for electromagnetic weapons.

  The cost of the onboard electronics represents a substantial fraction of
the total cost of a modern military aircraft, and therefore stock levels of
spares will in most instances be limited to what is deemed necessary to
cover operational usage at some nominal sortie rate. Therefore
electromagnetic damage could render aircraft unusable for substantial
periods of time.

  Attacking airfields with electromagnetic weapons will disable
communications, air traffic control facilities, navigational aids and
operational support equipment, if these items are not suitably
electromagnetic hardened. Conventional blast hardening measures will not be
effective, as electrical power and fixed communications cabling will carry
electromagnetic induced transients into most buildings. Hardened aircraft
shelters may provide some measure of protection due electrically conductive
reinforcement embedded in the concrete, but conventional revetments will
not.

  Therefore OCA operations against airfields and aircraft on the ground
should include the use of electromagnetic weapons as they offer the
potential to substantially reduce hostile sortie rates.

  10.4. Maritime Air Operations using Electromagnetic Bombs
  As with modern military aircraft, naval surface combatants are fitted with
a substantial volume of electronic equipment, performing similar functions
in detecting and engaging targets and warning of attack. As such they are
vulnerable to electromagnetic attack, if not suitably hardened. Should they
be hardened, volumetric, weight and cost penalties will be incurred.

  Conventional methods for attacking surface combatants involve the use of
saturation attacks by anti-ship missiles or coordinated attacks using a
combination of ARMs and anti-ship missiles. The latter instance is where
disabling the target electronically by stripping its antennae precedes
lethal attack with specialised anti-ship weapons.

  An electromagnetic warhead detonated within lethal radius of a surface
combatant will render its air defence system inoperable, as well as damaging
other electronic equipment such as electronic countermeasures, electronic
support measures and communications. This leaves the vessel undefended until
these systems can be restored, which may or may not be possible on the high
seas. Therefore launching an electromagnetic glidebomb on to a surface
combatant, and then reducing it with laser or television guided weapons is
an alternate strategy for dealing with such targets.

  10.5. Battlefield Air Interdiction Operations using Electromagnetic Bombs
  Modern land warfare doctrine emphasises mobility, and manoeuvre warfare
methods are typical for contemporary land warfare. Coordination and control
are essential to the successful conduct of manoeuvre operations, and this
provides another opportunity to apply electromagnetic weapons.
Communications and command sites are key elements in the structure of such a
land army, and these concentrate communications and computer equipment.
Therefore they should be attacked with electromagnetic weapons, to disrupt
the command and control of land operations.

  Should concentrations of armoured vehicles be found, these are also
profitable targets for electromagnetic attack, as their communications and
fire control systems may be substantially damaged or disabled as a result. A
useful tactic would be initial attack with electromagnetic weapons to create
a maximum of confusion, followed by attack with conventional weapons to take
advantage of the immediate situation.

  10.6. Defensive Counter-Air (DCA) and Air Defence Operations using
Electromagnetic Warheads
  Providing that compact electromagnetic warheads can be built with useful
lethality performance, then a number of other potential applications become
viable. One is to equip an Air-Air Missile (AAM) with such a warhead. A
weapon with datalink midcourse guidance, such as the AIM-120, could be used
to break up inbound raids by causing soft or hard electrical kills in a
formation (raid) of hostile aircraft. Should this be achieved, the defending
fighter will have the advantage in any following engagement as the hostile
aircraft may not be fully mission capable. Loss of air intercept or nav
attack radar, EW equipment, mission computers, digital engine controls,
communications and electronic flight controls, where fitted, could render
the victim aircraft defenceless against attack with conventional missiles.

  This paradigm may also be applied to air defence operations using area
defence SAMs. Large SAMs such as the MIM-104 Patriot, RIM-66E/M and RIM-67A
Standard, 5V55/48N6 (SA-10) and 9M82/9M83 (SA-12) could accommodate an
electromagnetic warhead comparable in size to a bomb warhead. A SAM site
subjected to jamming by inbound bombers could launch a first round under
datalink control with an electromagnetic warhead to disable the bombers, and
then follow with conventional rounds against targets which may not be able
to defend themselves electronically. This has obvious implications for the
electromagnetic hardness of combat aircraft systems.

  10.7. A Strategy of Graduated Response
  The introduction of non-nuclear electromagnetic bombs into the arsenal of
a modern air force considerably broadens the options for conducting
strategic campaigns. Clearly such weapons are potent force multipliers in
conducting a conventional war, particularly when applied to Electronic
Combat, OCA and strategic air attack operations.

  The massed use of such weapons would provide a decisive advantage to any
nation with the capability to effectively target and deliver them. The
qualitative advantage in capability so gained would provide a significant
advantage even against a much stronger opponent not in the possession of
this capability.

  Electromagnetic weapons however open up less conventional alternatives for
the conduct of a strategic campaign, which derive from their ability to
inflict significant material damage without inflicting visible collateral
damage and loss of life. Western governments have been traditionally
reluctant to commit to strategic campaigns, as the expectation of a lengthy
and costly battle, with mass media coverage of its highly visible results,
will quickly produce domestic political pressure to cease the conflict.

  An alternative is a Strategy of Graduated Response (SGR). In this
strategy, an opponent who threatens escalation to a full scale war is
preemptively attacked with electromagnetic weapons, to gain command of the
electromagnetic spectrum and command of the air. Selective attacks with
electromagnetic weapons may then be applied against chosen strategic
targets, to force concession. Should these fail to produce results, more
targets may be disabled by electromagnetic attack. Escalation would be
sustained and graduated, to produce steadily increasing pressure to concede
the dispute. Air and sea blockade are complementary means via which pressure
may be applied.

  Because electromagnetic weapons can cause damage on a large scale very
quickly, the rate at which damage can be inflicted can be very rapid, in
which respect such a campaign will differ from the conventional, where the
rate at which damage is inflicted is limited by the usable sortie rate of
strategic air attack capable assets [15].

  Should blockade and the total disabling of vital economic assets fail to
yield results, these may then be systematically reduced by conventional
weapons, to further escalate the pressure. Finally, a full scale
conventional strategic air attack campaign would follow, to wholly destroy
the hostile nation's warfighting capability.

  Another situation where electromagnetic bombs may find useful application
is in dealing with governments which actively implement a policy of state
sponsored terrorism or info-terrorism, or alternately choose to conduct a
sustained low intensity land warfare campaign. Again the Strategy of
Graduated Response, using electromagnetic bombs in the initial phases, would
place the government under significant pressure to concede.

  Importantly, high value targets such as R&D and production sites for
Weapons of Mass Destruction (nuclear, biological, chemical) and many vital
economic sites, such as petrochemical production facilities, are critically
dependent upon high technology electronic equipment. The proliferation of
WMD into developing nations has been greatly assisted by the availability of
high quality test and measurement equipment commercially available from
First World nations, as well as modern electronic process control equipment.
Selectively destroying such equipment can not only paralyse R&D effort, but
also significantly impair revenue generating production effort. A Middle
Eastern nation sponsoring terrorism will use oil revenue to support such
activity. Crippling its primary source of revenue without widespread
environmental pollution may be an effective and politically acceptable
punitive measure.

  As a punitive weapon electromagnetic devices are attractive for dealing
with belligerent governments. Substantial economic, military and political
damage may be inflicted with a modest commitment of resources by their
users, and without politically damaging loss of life.

  11. Conclusions
  Electromagnetic bombs are Weapons of Electrical Mass Destruction with
applications across a broad spectrum of targets, spanning both the strategic
and tactical. As such their use offers a very high payoff in attacking the
fundamental information processing and communication facilities of a target
system. The massed application of these weapons will produce substantial
paralysis in any target system, thus providing a decisive advantage in the
conduct of Electronic Combat, Offensive Counter Air and Strategic Air
Attack.

  Because E-bombs can cause hard electrical kills over larger areas than
conventional explosive weapons of similar mass, they offer substantial
economies in force size for a given level of inflicted damage, and are thus
a potent force multiplier for appropriate target sets.

  The non-lethal nature of electromagnetic weapons makes their use far less
politically damaging than that of conventional munitions, and therefore
broadens the range of military options available.

  This paper has included a discussion of the technical, operational and
targeting aspects of using such weapons, as no historical experience exists
as yet upon which to build a doctrinal model. The immaturity of this weapons
technology limits the scope of this discussion, and many potential areas of
application have intentionally not been discussed. The ongoing technological
evolution of this family of weapons will clarify the relationship between
weapon size and lethality, thus producing further applications and areas for
study.

  E-bombs can be an affordable force multiplier for military forces which
are under post Cold War pressures to reduce force sizes, increasing both
their combat potential and political utility in resolving disputes. Given
the potentially high payoff deriving from the use of these devices, it is
incumbent upon such military forces to appreciate both the offensive and
defensive implications of this technology. It is also incumbent upon
governments and private industry to consider the implications of the
proliferation of this technology, and take measures to safeguard their vital
assets from possible future attack. Those who choose not to may become
losers in any future wars.

  12. Acknowledgements
  Thanks to Dr D.H. Steven for his insightful comment on microwave coupling
and propagation, and to Professor C.S. Wallace, Dr Ronald Pose and Dr Peter
Leigh-Jones for their most helpful critique of the drafts. Thanks also to
the RAAF Air Power Studies Centre and its then Director, Group Captain Gary
Waters, for encouraging the author to investigate this subject in 1993. Some
material in this paper is derived from RAAF APSC Working Paper 15, "A
Doctrine for the Use of Electromagnetic Pulse Bombs", published in 1993
[KOPP93], and is posted with permission.

  An earlier version of this paper was presented at InfoWarCon V and first
published in "Information Warfare - Cyberterrorism: Protecting Your Personal
Security In the Electronic Age", 1996, Thunder's Mouth Press, 632 Broadway
7th FL, New York, NY, ISBN: 1-56025-132-8, http://www.infowar.com, posted
with permission.

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  MOTO3 - Motorola RF Device Data, Motorola Semiconductor Products Inc,
Arizona, 1983.

  NATSEMI78 - CMOS Databook, National Semiconductor Corporation, Santa
Clara, 1978

  NORTHROP95 - B-2 Precision Weapons, unclassified briefing,
Northrop-Grumman Corporation, September, 1995, unpublished material.

  NPI93 - NPI Local Area Network Products, SMD Transformers, Nano Pulse
Industries, Brea, 1993.

  PERGLER94 - Pergler R., Joint Standoff Weapon System (JSOW), unclassified
briefing, Texas Instruments, Inc., December 1994, unpublished material.

  RAMO65 - Ramo S. et al, Fields and Waves in Communications Electronics,
New York, John Wiley & Sons, 1965

  REINOVSKY85 - Reinovsky R.E., Levi P.S. and Welby J.M., An Economical, 2
Stage Flux Compression Generator System, Digest of Technical Papers, 5th
IEEE Pulsed Power Conference, pp.216, IEEE, New York, 1985.

  STAINES93 - Staines, G.W., High Power Microwave Technology - Part IV,
Military Applications of High Power Microwaves, Salisbury, DSTO ERL, EWD,
1993, draft paper.

  SZAFRANSKI95 - Szafranski R., Col USAF, Parallel War and Hyperwar, Chapter
5 in Schneider B.R, Grinter L.E., Battlefield of the Future, 21st Century
Warfare Issues, Air University Press, Maxwell AFB, September 1995.

  TAYLOR92 - Taylor C.D., Harrison C.W., On the Coupling of Microwave
Radiation to Wire Structures, IEEE Transactions on Electromagnetic
Compatibility, Vol. 34, No. 3, 183, August 1992.

  THODE87 - Thode L.E., Virtual-Cathode Microwave Device Research:
Experiment and Simulation, Chapter 14 in High Power Microwave Sources, 1987.

  VECK85 - van Eck W., "Electromagnetic Radiation from Video Display Units:
An Eavesdropping Risk", Computers and Security, 1985, pp. 269.

  WARDEN95 - Warden J.A. III, Col USAF, Air Theory for the Twenty-first
Century, Chapter 4 in Schneider B.R, Grinter L.E., Battlefield of the
Future, 21st Century Warfare Issues, Air University Press, Maxwell AFB,
September 1995.

  WATERS92 - Waters Gary, Gulf Lesson One, Canberra, Air Power Studies
Centre, 1992

  WHITE78 - The EMP - A Triangular Impulse, 2.29, A Handbook Series on
Electromagnetic Interference and Compatibility, Don White Consultants,
Maryland, 1978.

  Carlo Kopp Born in Perth, Western Australia, the author graduated with
first class honours in Electrical Engineering in 1984, from the University
of Western Australia. In 1996 he completed an MSc in Computer Science and is
currently working on a PhD in the same discipline, at Monash University in
Melbourne, Australia. He has over a decade of diverse industry experience,
including the design of high speed communications equipment, optical fibre
receivers and transmitters, communications equipment including embedded
code, Unix computer workstation motherboards, graphics adaptors and chassis.
More recently, he has consulted in Unix systems programming, performance
engineering and system administration. Actively publishing as a defence
analyst in Australia's leading aviation trade journal, Australian Aviation,
since 1980, he has become a locally recognised authority on the application
of modern military technology to operations and strategy. His work on
electronic combat doctrine, electromagnetic weapons doctrine, laser remote
sensing and signature reduction has been published by the Royal Australian
Air Force's Air Power Studies Centre since 1992, and he has previously
contributed to CADRE Air Chronicles.

  1 - Electromagnetic pulse or EMP device is a generic term applied to any
device, nuclear or conventional, which is capable of generating a very
intense but short electromagnetic field transient. For weapons applications,
this transient must be sufficiently intense to produce electromagnetic power
densities which are lethal to electronic and electrical equipment.
Electromagnetic weapons are electromagnetic devices specifically designed as
weapons. Whilst the terms 'conventional EMP weapon' and 'High Power
Microwave or HPM weapon' have been used interchangeably in trade journals
(see FULGHUM93), this paper will distinguish between microwave band and low
frequency weapons. The term 'electromagnetic bomb' or 'E-bomb' will be used
to describe both microwave and low frequency non-nuclear bombs. This paper
will not address the use of nuclear EMP, or alternate uses of HPM
technology. HPM technology has a broad range of potential applications in
EW, radar and directed energy weapons (DEW). The general conclusions of this
paper in the areas of infrastructure vulnerability and hardening are also
true for microwave directed energy weapons. This paper extends the scope of
earlier work by the author on this subject [KOPP93].

  2 - One bizzare instance of lightning strike electrical damage was
described to the author by an eyewitness technician, tasked with assessing
the damage on the site. A lightning bolt impacted in the close vicinity of a
transmitter shed. RF and power cables ran from the transmitter shed to a
transmission tower through a rectangular, metal shielded tunnel. The effect
of the lightning strike was to produce an electromagnetic standing wave in
the tunnel, much like in a microwave waveguide. All cables within the tunnel
were burned through at regular spacings along the tunnel, corresponding
precisely to the half wavelength of the standing wave in the tunnel.

  3 - The NACSIM 5100A standard specifies acceptable emission levels for
TEMPEST (Transient ElectroMagnetic Pulse Emanation Standard) rated
equipment.

  4 - The Northrop/Lockheed ASD-5 Black Crow DF receiver was fitted to the
AC-130A Pave Pronto gunships, rebuilt from obsoleted C-130 transports
[ICH10].

  5 - A noteworthy technical issue in this context is that even equipment
not-rated to TEMPEST standards will radiate energy at very low power levels,
in comparison with intentional transmissions by radar or communications
equipment. A receiver designed to detect, identify and locate sources of UE
radiation will either need to be highly sensitive, or deployed very close to
the emitter. It is worth noting that UE from computer monitors and networks
exhibit known regular patterns, and correlation techniques could be used to
significantly improve receiver sensitivity [DIXON84].

  6 - Fulghum D.A., ALCMs Given Non Lethal Role, AW&ST, Feb 22, 1993. This
recent report indicates that the US has progressed significantly with its
development work on electromagnetic warhead technology. An electromagnetic
warhead was fitted to the USAF AGM-86 Air Launched Cruise Missile airframe,
involving both structural and guidance system modifications. The description
in this report suggests the use of an explosive pumped flux generator
feeding a device such as a Vircator. References to magnetic coils almost
certainly relate to the flux compression generator hardware.

  7 - The Journal of Electronic Defence [JED96] recently reported on the
USAF Phillips Laboratory at Kirtland awarding a $6.6M HPM SEAD weapon
technology demonstration program contract to Hughes Missile Systems Co. This
contract will see Hughes conduct design studies in order to define design
goals, and then fabricate brassboard demonstration hardware using government
developed technology. JED speculate that the weapon will be a FCG driven
microwave tube, which is most likely the case given the USAF's prior
research activities in this area [REINOVSKY85]. An earlier report [JED95]
indicated the existence of a related program which addresses command and
control warfare and counter-air capabilities. In any event, the devices
produced by these programs are likely to become the first operationally
fielded HPM electromagnetic bombs for delivery by combat aircraft.

  8 - This may be readily determined by calculating the ratio of warhead
mass to total weapon launch mass, for representative missile types. Taking
the AGM-78 Standard as a lower limit yields 15.9%, whereas taking the
AGM/BGM-109 Tomahawk as an upper limit yields about 28%. Figures are derived
from manufacturers' brochures and reference publications eg Jane's
Air-Launched Weapons.

  9 - Staines, Fulghum. This is entirely consistent with theoretical
expectations, as the different spectral characteristics of microwave
electromagnetic warheads, compared to nuclear electromagnetic weapons, will
significantly affect the effectiveness of protective filters. What is
important from an electrical engineering viewpoint is that a filter designed
to stop signals in the lower frequency bands may perform very poorly at
microwave frequencies.

  11 - Gary Waters, Gulf Lesson One. Chapter 16 of this reference provides a
good discussion of both the rationale and implementation of this strategy.

  12 - Soft kill means will inhibit or degrade the function of a target
system during their application, leaving the target system electrically and
physically intact upon the cessation of their application. Hard kill means
will damage or destroy the target system, and are thus a means of inflicting
attrition.

  13 - This is also the stated intent of the USAF HPM SEAD technology
demonstration program. The fact that the first application of a HPM bomb is
electronic combat underscores the tactical, operational and strategic
importance of first defeating an air defence system when prosecuting a
strategic air war.

  14 - The classical argument here is centred upon Allied experience in
bombing Germany during WW2, where even repeated raids on industrial targets
were unable to wholly stop production, and in many instances only served to
reduce the rate of increase in production. What must not be overlooked is
that both the accuracy and lethality of weapons in this period bore little
comparison to what is available today, and automation of production
facilities was almost non-existent.

  15- This constraint primarily results from limitations in numbers.
Strategic air attack requires precision delivery of substantial payloads,
and is thus most effectively performed with specialised bomber assets, such
as the B-52, B-1, B-2, F-111, F-15E, F-117A, Tornado or Su-24. These are
typically more maintenance intensive than less complex multirole fighters,
and this will become a constraint to the sortie rate achievable with a
finite number of aircraft, assuming the availability of aircrew. Whilst
multirole fighters may be applied to strategic air attack, their typically
lesser payload radius performance and lesser accuracy will reduce their
effectiveness. In the doctrinal context, this can be directly related to
existing USAF aerospace doctrine [AFM1-1], in several areas.

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  A version of this article was first published in: "Information Warfare -
Cyberterroism: Protecting Your Personal Security in the Electronic Age" by
Winn Schwartau, 1996 Thunder's Mouth Press, 632 Broadway 7th Fl, New York,
New York, ISBN: 1-56025-132-8, http://www.infowar.com

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  The conclusions and opinions expressed in this document are those of the
author cultivated in the freedom of expression, and academic environment of
Air University. They do not reflect the official position of the US
Government, Department of Defense, the United States Air Force or the Air
University.

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