See Steve Perlman's efforts at making a cellular radio system that can focus a 'bubble' of cellular energy around the user.[1] Call 'pCell' or 'pRadio' in various press releases it basically is a MIMO setup that uses many cell towers to transmit a pre-distorted signal that converges into a power signal at a particular point in space. At the time it was announced I suggested it sounds like something that could be weaponized if you wanted to. Being able a turn a microwave on around a person without anyone nearby noticing anything is a pretty capable thing.
If the signal is strong enough, you can easily design a pocket detector. A PCB attached to a pocket protector with antenna tracings for multiple spectrums and a buzzer. No need to get fancy, a few passives off the shelf will do the trick. Or just get a SDR scanning multiple spectrums and have a threshold trigger above a specific power level. This is beginner radio stuff, I am sure their local hardware tech support can whip one up under a day.
I wonder if you could just have a calorimeter and a block of material with similar properties to human tissue? That way you cover the EHF/THF(>30GHz) ranges as well?
Sure but then you have a targeting problem, which in the radio range is not trivial particularly when you've got intervening objects and no receiver providing feedback about signal strength.
Sort of right? I mean how big is the field? How often does someone move the bed in a hotel room? If you were set up outside a hotel where you knew targets slept, you could program constants for the bed in each room right?
Further if you knew what you were trying to do, you could set up your feedback transmitter in a room, record all the parameters for that room, then move to the next room, Etc.
The problem that Perlman was solving was a lot harder (a moving target) but hitting a nominally stationary target?
Embassies are constantly swept for bugs and transmitting radio devices. The security officer in an embassy is always going to be an intelligence officer. Particularly US embassies, are not lax security targets along any dimension.
If it is strong enough to affect the human physiology then it can be detected regardless how short lived it is. If your neighbor honks the car 3 times at 3 in the morning you will still hear it even though it is only for a few seconds. If you are watching a real-time football match on LTE and drives through a tunnel with no signal, there will still be a interruption even if the tunnel is very short.
Depends on how tight the beam is and how high gain on the receiving antenna. For a point of reference: radio transmitter => light source, focused beam => light focused with a lens, antenna gain => strength of lens. If you have any questions, just visualize the system (or draw it out) as a series of light sources and light sensors. RF and light are both radiation and follow the Maxwell equations. (Optics are sometimes considered to have additional properties mostly due to limitations in our current understanding of certain RF spectrums, see terahertz bandgap but by and large they follow the same rules).
This is nonsense. If the power level is high enough to do damage, detecting it would be trivially easy.
Just a wire dipole, a diode, and a simple meter will do the job. At most it would require a set of dipoles to cover each band of interest.
Most radio hobbyists could make a set of dipoles from an a old coat-hanger in a few minutes.