You can find refs about this fucking up Stealth(tm) aircraft's stealthiness during one of the recent wars... possibly in England? Basically you have lots of emitters (basestations) probing the RF reflectance of their environment over time, reporting back to central stations... even angular dissipatively-clothed airframes will have signatures.
One could do classroom tabletop experiments with e.g., some gunn devices, adsorbtive foam, metal foil, and simple diode detectors. Scripted Mr Scribe: "The technology 'sees' the shapes made when radio waves emitted by mobile phone masts meet an obstruction. Signals bounced back by immobile objects, such as walls or trees, are filtered out by the receiver. This allows anything moving, such as cars or people, to be tracked. Previously, radar needed massive fixed equipment to work and transmissions from mobile phone masts were thought too weak to be useful." Not enough detail in there to answer many questions - anyone have any more info on this?
