Antennas for concealed weapon detection

Detection of concealed weapons is limited first by the signal to clutter ratio, and hence a trade between antenna beamwidth versus range to the suspect. An approach is described based on crossed focused line source antennas to produce a small common (transmit-receive) footprint on the subject being examined. These antenna beams can be phased, but a cost-effective approach is to use a Rottman lens (with switched input/output ports) in order to resolve the surveillance area into multiple overlapping antenna beams. The concealed weapon detector antennas can be covertly mounted on a door or wall or camouflaged as other facility structure components. Upon detection, a weapon alert subsystem communicates the presence of a suspect carrying a concealed weapon to authorities through a wireless or wire network. Alternatively the system can trigger other subsystems, such as cameras to track the suspect on a video recorder.