Well, cell phone towers may actually be being used as
look-through-walls capable real time imaging surveillance
devices and no one - except maybe the people doing it
and the Taliban - seem to be aware that this even a possibility.
It was pointed out to me that at the frequency that most
cell phone systems operate at, the wavelength is so long
(about one meter) that a return from it would be pretty useless
for imaging. But 4G systems are close to 3Ghz and that brings
it down to around 1/10 of a meter - say, 4 inches..
Maybe close enough for government work.
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