Yeah, it actually looks like you can buy them on Amazon for about 30$. I don’t want to doubt but this seems so simple to test that the lack of any direct evidence makes me suspicious.

https://www.amazon.com/Electromagnetic-Radiation-5HZ-3500MHz...

The descriptions of the attacks seem to indicate a pretty narrow beamwidth, so you'd probably have to wear it on a helmet :)

At intensities that would injure, you light up the whole neighbourhood with scattered radiation. There's no hiding this attack from a sensor in the vicinity.

The math would be interesting to see. I haven't seen a directed energy antenna, but you can easily drop 9db with single digit degrees off target with a big dish.

9dB is really not a lot. If you're going to be sending 10kW+ of radiation 9dB of directionality still means you're gonna light up the whole neighborhood.

In the most literal sense of the word. 1 KW at 100 meters on a directional antenna like that will happily light up neon tubes. The field is going to be a few hundred V/meter.

This kind of device seems marketed towards people who think EM waves in general are bad for them. It says it can't detect RF radiation while it clearly says 3.5Ghz in the description, so I think it might be a scam.

Regardless of that, wideband EM receivers exist, and the US has some with incredibly high sensitivities.