• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer

Test & Measurement Tips

Oscilloscopes, electronics engineering industry news, how-to EE articles and electronics resources

  • Oscilloscopes
    • Analog Oscilloscope
    • Digital Oscilloscope
    • Handheld Oscilloscope
    • Mixed-signal Oscilloscope
    • PC-based Oscilloscopes – PCO
  • Design
  • Calibration
  • Meters & Testers
  • Test Equipment
  • Suppliers
  • Video
  • EE Learning Center
    • Design Guides
      • WiFi & the IOT Design Guide
      • Microcontrollers Design Guide
      • State of the Art Inductors Design Guide
  • FAQs
You are here: Home / Editor's Blog / Microwaves and the Havana Syndrome

Microwaves and the Havana Syndrome

June 14, 2021 By Lee Teschler 4 Comments

Leland Teschler • Executive editor

The National Academy of Sciences recently released its conclusions about what sickened dozens of American Embassy diplomats in Cuba, a phenomenon dubbed the Havana Syndrome. Though the panel reached no definitive conclusion, it found pulsed RF (a.k.a. directed microwave energy) was the most likely cause. Panel members could not rule out the possibility that the whole episode was a case of mass hysteria but considered the idea unlikely.

The directed microwave energy theory rests on what’s called the microwave auditory effect. When a human head Lee-Teschlerabsorbs a pulse of RF energy, a rise in temperature causes tissue inside the head to expand slightly. The expansion launches a pressure wave that propagates throughout the skull to the inner ear, potentially causing clicking or buzzing sounds. Fortunately, the temperature rise is tiny (microdegrees) and the pressure wave is far too weak to injure tissue unless the microwave power density is huge.

Critics have pooh-poohed the directed energy conclusion, claiming a microwave generator big enough to cause tissue damage would stick out like an NBA center at a jockey convention. Fortunately, there is open research on directed energy effects. So sufficiently interested individuals can do a little research and draw their own conclusions.

One paper in this area published in Frontiers of Neurology points out experimenters were able to kill rats by exposing them to 2.45 GHz microwaves with a field intensity of 1,000 W/cm2. There’s no data in the open literature on the threshold of microwave power that causes human brain damage, but the researchers suggest a minimum intensity of 1 W/cm2 impinging on the human head–using 50-µsec pulses on a 7 kHz repetition rate–might be a good place to start.

It has also been reported that the wife of a member of the Cuban embassy staff once looked outside her home after hearing disturbing sounds and had seen a van speeding away. The implication is that the microwave generator was small enough to fit in the van. Also, the incident provides a means for making a ballpark estimate of range; we might say 150 ft from the street to the woman’s home would be a reasonable guess.

So here’s how the calculation shakes out: We want to know the minimum output power of a 2.45 GHz microwave generator able to produce at least 1 W/cm2 inside a house 150 ft away, through at least one wall. (For simplicity, we’ll assume the van was transparent to EM radiation.) We might also assume the transmitter is teamed with a parabolic antenna. A 6-ft-diameter parabolic antenna, which should fit in a van, can add about 30 dB of gain at 2.45 GHz.

Using these parameters in a back-of-the-envelop calculation will lead you to conclude that the 2.45-GHz transmitter must put out at least 2 MW to get the job done. Today, a 2-MW transmitter in the 2.45-GHz range is about the size of a laundry basket and weighs about 150 lb. So it can certainly fit in a van, along with a power supply and modulation source, while leaving room for a human operator.

If this scenario really did unfold as we theorize, we doubt the frequency used was smack in the middle of the WiFi band as in our example. (Though perhaps that doesn’t matter in Cuba.) But big microwave generators put in place to hassle diplomats seem to be at least theoretically feasible.

Of course, there is one question this exercise doesn’t answer: Given all the controversy over pulsed microwaves, why not just stick spectrum analyzers in the homes and offices of U.S. diplomats? If this simple solution was mentioned in the NAS report, it certainly isn’t getting any press coverage.

You may also like:

  • 5G
    Will 5G be lethal?
  • rental instruments
    The modern economics of renting test instruments
  • no you can't detect ghosts with a gauss meter
    No, you can’t detect ghosts with a gauss meter
  • leland-teschler-and-oscilloscope-feat
    No nostalgia for old test instruments
  • distributed C-L model
    Understanding the basics: What is characteristic impedance?

Filed Under: Editor's Blog, FAQ, Featured Tagged With: FAQ

Reader Interactions

Comments

  1. Lucius says

    June 23, 2021 at 11:18 am

    Another question is: What’s the motive? Diplomats are not invaders – they are guests – so why would Cuba want to injure them? If Cuba didn’t want them there it could just expel them, as other countries do to diplomats all the time.

    Log in to Reply
  2. Celsiuss Watts says

    June 27, 2021 at 1:12 pm

    When the effects of microwaves are considered. two mechanisms are at guess. One is evident – thermal effects – but this needs to be strong enough to penetrate deep into tissues (mostly consumed by ~1mm skin at 5GHz and ~10-12mm at 2.5Ghz). The second is resonant frequency selective effects, and there are science fiction books on it, while the researches do not agree yet whether effects exist or not. The energy can be easily blocked my metal meshes (some embassy buildings have screened rooms), and security officers were supposed to detect such invasion by RF detectors. Besides, the radiation of that range is produced by cell phones and microwave ovens, and some effects of continuous exposure to such sources could be also reported. There are plenty of test equipment that could easily discover sources known to physics, so most likely they were not of brute force physics nature.
    But talking of conspiracies, embassies and microwaves – it makes sense to mention forgotten story: https://en.wikipedia.org/wiki/The_Thing_(listening_device) – which may explain “why”

    Log in to Reply
  3. SXP says

    July 11, 2021 at 10:50 am

    is there an off the shelf analyzer or detector that you will recommend? Asking as someone who has family overseas who are US diplomats in an area where similar incidents have happened.

    Log in to Reply
    • Lee Teschler says

      July 13, 2021 at 12:29 pm

      Basically what you are looking for is a spectrum analyzer. You’ll need one that covers the WiFi frequency band and up. The most economical spectrum analyzers I’ve seen are those that work in conjunction with a PC. Off the top of my head, Pico and Signal Hound both have units that might work but there are probably other manufacturers as well.

      Log in to Reply

Leave a Reply Cancel reply

You must be logged in to post a comment.

Primary Sidebar

Current Digital Issue

A frequency you can count on There are few constants in life, but what few there are might include death, taxes, and a U.S. grid frequency that doesn’t vary by more than ±0.5 Hz. However, the certainty of the grid frequency is coming into question, thanks to the rising percentage of renewable energy sources that…

Digital Edition Back Issues

Oscilloscopes Finder

Search Millions of Parts from Thousands of Suppliers.

Search Now!
design fast globle

Subscribe to our Newsletter

Subscribe to test and measurement industry news, new oscilloscope product innovations and more.

Subscribe Today

EE TRAINING CENTER CLASSROOMS

EE Classrooms

RSS Current EDABoard.com discussions

  • Load Step Response Test Using Siglent SDL1000X-E DC Load and SDS2000X Plus Oscilloscope
  • Op amp non inverting amplifier not working
  • Measure AC current accurateley (100mA to 10A)
  • Mosfet SSR triac output shunt circuit design
  • Tessent MBIST for memories with dedicated test clock

RSS Current Electro-Tech-Online.com Discussions

  • Funny Images Thread!
  • Two 300nH inductor in series, can get higher current?
  • Best way to reduce voltage in higher wattage system?
  • surge arresters
  • Someone please explain how this BMS board is supposed to work?

Footer

EE World Online Network

  • DesignFast
  • EE World Online
  • EDABoard
  • Electro-Tech Online
  • Analog IC Tips
  • Microcontroller Tips
  • Power Electronic Tips
  • Sensor Tips
  • Connector Tips
  • Wire and Cable Tips
  • 5G Technology World

Test & Measurement Tips

  • Subscribe to our newsletter
  • Advertise with us
  • Contact us
  • About us
Follow us on TwitterAdd us on FacebookFollow us on YouTube Follow us on Instagram

Copyright © 2022 · WTWH Media LLC and its licensors. All rights reserved.
The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media.

Privacy Policy