“Whether or not a microwave weapon was the culprit, this stealth technique may be a weapon of the future. I would not be surprised if some military establishment around the world invests or has already been engaged in such a program.”

Professor James Lin — UIC

Professor James Lin

Two months ago, I suggested than a microwave weapon — and not sonic attacks — may be the cause of the “Havana syndrome”. Professor James Lin just published a paper on the possibility that the Havana syndrome might indeed be explained by a secret microwave weapon. Professor Lin has kindly agreed to review the known facts about this case and compare them to our current knowledge of ‘microwave weapons’. Follow us on Twitter: @INTEL_TODAY

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Professor James Lin, an expert in Electrical Engineering at the University of Illinois at Chicago. His research interests include: Biomedical instrumentation; Electromagnetic Engineering for Biology and Medicine; Imaging and Sensing; Bioelectromagnetics; Mobile Telecommunication Safety; Biological Interactions of Electromagnetic Radiation Including RF, Microwaves, and Lasers.

In a recent publication, Professor Lin suggests that microwave weapons could have generated the mysterious sounds heard by the US spies in Havana.

Specifically, Lin points out that:

“It is plausible that the loud buzzing, burst of sound, or acoustic pressure waves may have been covertly delivered using high-power microwave radiation, rather than blasting the subjects with conventional sonic sources.”

(…)

“Studies have shown that the auditory phenomenon occurs at a microwave radiation specific-energy-absorption rate threshold of 1.6 W/g for a single 10 μs wide pulse of microwaves aimed at the subject or subject’s head…”

Depending on the power density of the microwave pulses, the induced sound pressure could cause serious discomfort to the subject.

This type of microwave attack could explain the various reported effects such as ear-ringing, permanent hearing loss, balance trouble, dizziness, nausea and even brain tissue injuries.

Definition —  Radio frequency (RF) is any of the electromagnetic wave frequencies that lie in the range extending from around 20 kHz to 300 GHz, roughly the frequencies used in radio communication.

[INTEL TODAY — Please, understand that 300 GHz is NOT the upper limit of Non Ionizing radiations! Some countries — such as Belgium — have laws that are totally mistaken about this definition with numerous and grave consequences.]

The term does not have an official definition, and different sources specify slightly different upper and lower bounds for the frequency range.

Frequencies of 1 GHz and above are conventionally called microwave, while frequencies of 300 GHz and above are designated millimeter wave.

More detailed band designations are given by the standard IEEE letter – band frequency designations and the EU/NATO frequency designations. [Wikipedia]

Microwave Weapons — What do we know?

I have contacted Professor Lin who kindly agreed to help me reviewing the key facts in order to assess the plausibility of a microwave attack. The following facts are scientifically well established.

When exposed to a repeated sequence of RF pulses, a human subject could experience a sensation of “hearing” some type of sound, including noise.

For this to actually happen, the RF pulses must have a minimal power density. Various experiments conducted at several microwave frequencies and various pulse lengths (from 1 to 100 microsecond) suggest that an average power density of 0.1 milli Watt per cm2 is sufficient to trigger this effect.

The tone heard by the subject is – at least in good approximation – independent of the RF frequency. Instead, the tone would depend on the microwave pulse width, number of pulses, and repetition cycle or rate.

For a ‘normal adult’, the range of the ‘RF sounds’ that can be perceived will go from about 7 to 15 kHz. It does depend on the size of the head but also on the response of the subject to acoustic waves. People with high audio frequency hearing loss, would not hear such RF induced sound or experience acoustic effect.

According to US media, the sounds — described by the US diplomats — range from 7 to 10 kHz. That is absolutely compatible with the RF acoustic effect.

But is it Plausible?

Based on the facts explained just above, a microwave attack certainly appears possible. But is it plausible? How big would such ‘microwave gun’ need to be?

A US professor recently claimed that a RF weapon powerful enough to trigger the effect would have to be very large and thus unpractical.

Building a microwave pulse gun, however, is an implausible concept, according to Kenneth Foster, New Scientist reports.

“That theory is a real stretch,” the bioengineering professor at the University of Pennsylvania says.

“It would require something like a major airport radar transmitter with the subject’s head close to the antenna in its direct beam … I guess it is possible, but not likely.”

I find this argument quite dubious and confused. The effect was indeed discovered by people working near airport radars. But that does not imply that such large devices are needed!

Professor Lin strongly disagrees with Foster’s comment . [INTEL TODAY — There is no doubt that Prof. Lin is absolutely correct about this.]

“To my knowledge, he does not have any, “actual” experience in producing hearing through microwave auditory effects in animals or humans.

The experimental setup does not need to be large and it is not difficult to do, if one has a high power pulsed microwave generator. All other equipments are commonly available lab electronic instruments.

They can be arranged on a typical lab bench or small SUV-size automobile, to produce the phenomenon at a threshold hearing  level or trigger the microwave auditory effect.”

Brain Damage?

Finally, US Medical tests reveal that the brains’ victims have change in their ‘white tracts’.

“Whether it is the white matter, grey matter or any other brain tissue, potential damages to brain tissue would depend on several factors  such as frequency and intensity of pulsed microwave or RF radiation, and the intensity and duration of the shock wave or acoustic wave of pressure generated inside the head.

I would not expect any brain tissue damage at threshold hearing level.”

This final point is a bit puzzling but keep in mind that there is no way to know if these changes are actually related to the attacks or if they were caused by past experiences.

This is an important point considering that it is known that most — if not all — US diplomats who suffer from the Havana syndrome are actually spies who may have had a career in the military and may have been exposed to explosions for instance.

REFERENCES

Mass Hysteria or Microwave Weapons—What’s Behind the ‘Sonic Attacks’ On U.S. Diplomats — Newsweek

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Havana Syndrome & Microwave Weapons: Q&A with Professor James Lin