The radar guns police use to spot speeding motorists have inspired a version that aims to identify a would-be suicide bomber in a crowd.
A radar gun fires microwave pulses at a car and measures the Doppler shift of the reflected signal to calculate its velocity. However, the strength and polarisation of the reflected signal – the "radar cross section" – can provide additional information about the size and shape of the reflecting object and the material it is made from.
William Fox of the Naval Postgraduate School in Monterey, California, and John Vesecky of the University of California, Santa Cruz, wondered whether the wiring in a suicide vest would alter the radar cross section of a bomber enough to allow a radar gun to pick him or her out in a crowd.
To find out, the pair used software to simulate how radar signals at 1 gigahertz and 10 gigahertz would be reflected by the most common arrangements of looped wiring typically used by suicide bombers. They found that the clearest reflected signals were in the 10 gigahertz range...
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Paul Marks @'New Scientist'
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