Introduction

 

In March 2001, a representative of the United States Air Force made a short statement at the press conference about existence of a new weapon called Active Denial Technology (ADT).

 

The bullet of this weapon is the microwave electromagnetic radiation.

ADT should be operating at the frequency of 95 GHz (wavelength l = 3.16 mm) and its transmitter power should be 100 kW. The microwave electromagnetic radiation should penetrate 0.4 mm (1/64 inch) deep into the skin and cause such a pain sensation that the radiated person should run away to avoid it. The weapon is intended to control the crowds.

 

The weapon should be humane, nonlethal, invisible and inaudible. No ballistic correction is needed and its bullet, i.e. the microwave electromagnetic radiation spreads with the velocity of light.

 

The scientists and sponsors, participating in the project, declared it to be the most revolutionary weapon since the atom bomb. The news was published in all the important newspapers of the world and other media.

 

Thus the secret that has been exiting curiosity of professionals in this area for more than one decade has been unveiled.

Photos, such as this one, of ADT appeared, but no technical data were available. In the course of time, however, few pieces of information were disclosed. The author has examined and compared American, English and German sources of information prior to making analysis of the weapon.

 

As shown in the photo the "gun" of this weapon is a microwave antenna called parabolic antenna. It has the shape of a dish and radiates electromagnetic energy in a narrow beam. The larger parabolic antenna is the narrower beam it radiates by which gain of the signal increases.

 

The ADT effective range primarily depends on the size and type of parabolic antenna. Therefore, a few of its basic characteristics should be examined first.

 

Effective range and choice of ADT radiation antenna

 

A conventional microwave parabolic antenna has three radiation zones as shown in the figure.

In the table below, distances of the zones are given for 1m, 2m and 3m diameter parabolic antennas and corresponding widths of main radiation beams are calculated.

 

Electromagnetic radiation of microwave parabolic antennas is usually measured or calculated either as power density S (W/m²) or electric field strength E (V/m).

Experts in antennas acknowledge that the distances of the near and transition zones are vast.

 

The following are the properties of the three zones.

In the near zone the power density S and the electric field strength E reach their absolute maximum on the axis of parabolic antenna, in the transition zone S falls linearly and in the far zone with the square of the distance.

 

The distance where the power density S falls from its maximum to half of the value, i.e. by 3 dB, is called effective range of the weapon. This is a generally accepted criterion when electromagnetic radiation is treated.

 

The following figure shows relative power density versus distance for a 2m parabolic antenna.

The maximum power density occurs at 317 m and falls to half of its value at 640 m. The effective range of a 2m parabolic antenna is 640 m although account should be taken of the fact that there are few windows, which are unavoidable, in its nearest vicinity where S is lower. For a 3m parabolic antenna the values are 712 m and 3900 m respectively.

 

The size of the parabolic antenna shown in the photos may be a little more than 2 m. The Pentagon's representative stated the effective range of ADT to have been approximately 700 yards, which agrees with our calculation.

 

Efficiency of a conventional circular parabolic antenna is 50 - 60 %. The efficiency mainly depends on roughness of its surface. The roughness should not exceed 1/16 of its wavelength, which is 0.2 mm in our case. Development and construction of a 2m or 3m circular parabolic antenna with that roughness would entail huge costs and require special tools to be developed.

 

To avoid high costs of construction FLAPS (flat parabolic surfaces) technology was used in constructing the ADT antenna. On its flat surface little dipoles are set in groups (see the figure).

Efficiency of a FLAPS antenna is 95 %; it is also possible to scan its main beam to a certain extent so that mechanical rotation is not necessary.

Its characteristic values are calculated using the same method as for a conventional parabolic antenna.

 

For ADT mobile construction a folding FLAPS antenna is used, which is its great advantage when transport in strong wind is required.

Choice of frequency

 

Conditions imposing the choice of frequency 95 GHz are as follows:

 

– Attenuation of electromagnetic waves through real atmosphere has a window at the frequency of

95 GHz and also at other frequencies (34 GHz, 140 GHz, 240 GHz), which is shown in the figure below;

– Transmitting technology has already reached these frequencies;

– Nearly all countries in the world use the measuring technology up to 50 GHz and consequently cannot measure the signals at the frequency of 95 GHz.

 

Other frequencies or areas of electromagnetic radiation could not be taken into consideration since:

 

– The frequency of 34 GHz is rather occupied and can be measured in nearly all countries,

– Infrared radiation (0.78 to 100 μm) is visible and can be measured,

– Visible light (0.39 to 0.78 μm) can be seen,

– Ultraviolet (UV) radiation (0.20 do 0.39 μm) is harmful to cells and causes cancer of the skin,

– Laser (λ = 380 to 950 nm): it has been established that the level causing pain may blind the man.

 

Effects on human beings ... strength and form of the signal, transmitter 

 

Effects of electromagnetic radiation on human beings depend on the frequency, strength and form of the signal.

Strength and form of the signal depend on the transmitter power.

Effects of electromagnetic radiation on human beings are divided into thermal and non-thermal.

Thermal effects 

Tests were made on a model human being with temperature 34 ºC. The US scientists established that the model perceived variation in temperature by 0.1 ºC, which means the power density of 45 W/m². Pain threshold occurs at the temperature higher by 10 ºC, which means S_min = 12 500 W/m².

To achieve the pain threshold at the edge of the ADT effective range (640 m), the power density should be doubled to 25 000W/m².

Yet, by power density S = 25 000 W/m² only the pain threshold is reached.

General professional public has not known the strength of the microwave radiation power density that would cause pain sensation forcing the man to withdraw, still without any injuries, yet. For that purpose the manufacturers are performing further tests.

A simple example might be of help.
The maximum radiation power of the sun has usual value 800 W/m². In secondary school textbooks of physics an example of focusing the sunlight using a 5 cm lens is given. When a beam of sunlight is reduced approximately to the width of 8 mm it causes unbearable pain sensation in less than a second. The strength of electromagnetic radiation of the visible light increases from 800 W/m² to  31 250 W/m² by focusing.

Therefore, the strength of radiation at the frequency of 95 GHz causing a pain sensation should be doubled at least to exceed twice its threshold value thus causing a severe pain. In that case the power density S_d,max  would be 50 000 W/m². 

Transmitter

In order to reach double threshold pain sensation at the maximum of the ADT effective range the transmitter power of a 2m parabolic antenna with 95 % efficiency should be:

P_d,max ≥ 0.83 S_d,max= 41 500 W.

Consequently, at the edge of the ADT effective range double power is necessary, i.e. 83 000 W.

However, this power would not be sufficient. To transfer the energy from a transmitter to antenna a wave-guide is used. At the frequency of 95 GHz the losses of energy are inevitable and amount to 20 % approximately when high technology confocal wave-guides are involved.
Taking into account all the above, the power of the transmitter should be at least 100 kW.
Pentagon declared the power of the ADT transmitter to be 100 kW although no further explanation of the power was given.

The following will help us to arrive at the correct conclusion. There are two types of power - the average and peak.

The average power means the power that heats a certain quantity of water to a certain temperature, or, heats the skin and causes a pain sensation. When lower frequencies are involved this power is called effective transmitter power.
So far, it has not been heard or seen that a transmitter with effective power of 100 kW and the frequency of 95 GHz would exist.
Most certainly it is the peak power and pulse transmission that are involved.

 

What is the transmitter made of?

It is impossible to use solid-state technique as its technology is far from reaching such powers and frequencies.

In fact, electron tubes, which are history nowadays, are used, modernized of course.

A traveling wave tube (TWT), known for a few decades already and used in microwave ovens, could not be taken into account since its power is at least by 10-times too low.

 

In the recent years special tubes called gyrotrons have been developed.

They are used for

– High-resolution radars,

– Nucleus fusion,

– Particle acceleration,

– Sources of high power and high frequency microwave radiation.

 

The following is the principle of its operation (see the figure below)

:

An electron gun, usually a magnetron, emits electrons. Applied electric field draws electrons from the negative cathode (electron gun) towards the positive anode.

Extremely strong magnetic field of supra conducting magnets in helium (3 to 4 T) makes the electrons rotate at the gyro frequency. The electrons travel through the cavity where the electrons beam is gained. At the radio frequency output electromagnetic waves of high frequencies and powers are obtained.

In the recent years gyrotrons of enormous powers have been developed resulting also in pulses of longer duration.

By the end of 2001 the news came out that an order was placed with the company CPI for the manufacture of a transmitter. Indeed, soon afterwards a new type of gyrotron VGB-8095 appeared on the company's website. Its characteristics are: power 100 kW, frequency 95 GHz, continuous wave transmission.

Most certainly it is part of the ADT transmitter that is in question.

Nearly every part of ADT is the latest technical achievement of the topmost high technology.

 

Non-thermal effects

 

In all available Pentagon documents the intention of ADT is described as not causing any injuries to people. It should only discourage them from any bad intentions. Thermal effects should achieve such a reaction and no side effects should occur at all.

 

Nevertheless, non-thermal effects of the electromagnetic radiation cannot be ignored. They occur when signals more than 100-times lower than the signals described in this article, are involved, to mention only two of them, i.e. microwave hearing and microwave mind control.

 

Experts in this area are acquainted with the fact, which has also been demonstrated, that emission of special microwave pulses at low frequencies and regular intervals causes certain perception, such as hearing of the waves behind the head, buzzing, ringing, beating, etc. In certain people this causes rapid heart beating or higher blood pressure.

 

This effect has been observed and measured only in the frequency range of 300 MHz to 10 GHz. No reliable data are available for higher frequencies. A. Frey, a renowned expert, who made it public and also measured the phenomenon back in 1962 thought that at the frequency of 95 GHz this phenomenon could not occur.

 

The control of mind with electromagnetic waves is rather complex and concealed matter. It is known that human brain emits and receives alpha, beta and theta electromagnetic waves of frequencies 5 to 16 Hz inside the human body. External electromagnetic field emitting microwave pulses of similar frequencies may cause special effects in human beings.

 

Here, the bombing of the US embassy in Moscow back in 1980 should be mentioned. At that time, Russians certainly did not dispose of any such technology that would emit electromagnetic waves of powers causing burning pain; so the only possible conclusion is that non-thermal effects and lower powers of signals were involved.

The ADT FLAPS antenna can operate at two totally different frequencies. Therefore, from the technical point of view it is also possible that ADT emits at the frequencies and such levels that would cause additional non-thermal effects.

 

This might be indicated in the name of the weapon by the term “denial”. According to Sigmund Freud

"Denial occurs in cases where the ego is threatened and a person refuses to acknowledge the reality or seriousness of the situation. Identification involves empathizing with the qualities or characteristics of another favorable person. Fixation and Regression are related mechanisms which occur during psychosexual development."

 

So far, Pentagon has often given names with certain meaning to numerous weapons.

It was published that over 1600 tests were performed on 72 volunteers. Except for one burning no physical injuries whatever were reported to have occurred. On another occasion, certain non-thermal effects were reported to have occurred after approximately 6 minutes of radiation that need to be investigated. 

Tests on ADT should be performed up to 2009. Undoubtedly, further news will follow.
 

Possible protection against ADT will perhaps be discussed on another occasion.