Spying using microwaves

5G is Millimeter Waves.

https://www.dfrobot.com/blog-1649.html

Guess what else uses millimeter waves. Non-lethal directed-energy weapons.

https://jnlwp.defense.gov/About/Frequently-Asked-Questions/Active-Denial-System-FAQs/

@Shallow-Blue
I'll bet people think my post above is a conspiracy theory, but it is not. I simply stated a fact. I'm sure at low intensity millimeter waves are fine as a communications frequency just as microwaves are. That does not mean I would live near a cell tower though. Distance is the key to being safe. Too close is unsafe.

https://ehtrust.org/firestation-closes-due-to-cell-tower-radiation-issues/

This whole idea really started with the Woodpecker Signal, a noise generated at around 10 mhz to disrupt life in the US, broadcast along electrical cabling. About four years or so ago I bumped into an article that said that electrical appliances could be used as microphones to listen in (transmitting outbound along the mains ring), but they would have to be built for that purpose? We live in a surveillance society, so I wouldn't be surprised if this was all going on.

https://www.warhistoryonline.com/instant-articles/russian-duga-radar-woodpecker.html

@medullah
That was an early cold war over the horizon radar that relied on low frequency waves that reflect off the underside of the ionosphere so could shoot a radio wave thousands of miles and a reflection coming back could be analysed to give data on aircraft and such but it couldn't have been very effective because of the low frequency, radar only became militarily useful when the Varian brothers invented the Klystron which allowed radar to run at 5 or so gigahertz, the first radar invented by the Brits ran at about 1 meter wavelength, about 300 megahertz and the radar returns did not have enough resolution to discern planes as enemy or friendly.
But when they were able to shoot out megawatt 5 gigahertz waves the returns had a LOT more data as to what was flying, like how many engines and so forth with some sixteen times the resolution of the first generation British radars.
I know a bit about radar, that was part of my job when I was in the USAF.

Now think about the res you get with a signal some 30 meters in wavelength, maybe it would identify an aircraft carrier a thousand feet long but a single aircraft, no way.
For example, semiconductor chips use light to impress patterns on the chips to allow smaller and smaller individual transistors and such, and the first ones used IR light which was fine when the transistors were a couple of microns or bigger in size but to get progressively smaller and smaller feature sizes they had to go to shorter and shorter wavelengths so now they are using something like 13 nanometer wavelength, deep ultraviolet and now pushing out 3 nanometer parts which is amazing in itself but they are pushing down to 2 nm next year and word on the street is Moore's law poops out at 1.5 nm parts so what they do after that I don't know, since you start counting individual atoms at that point.

But the main point is for any instrument, radar, telescopes, microscopes, the shorter the wavelength you can tune to the better the resolution and 30 meters won't by you much as a radar.
30 meters is about 100 feet so you might get 50 feet of res but forget getting say 5 feet but our newest radars now get more like 2 feet of res.