Radar Reflector

Floor 1 | Mirrors in Mind
When light strikes a rough surface it is reflected all over the place. Now polish that surface to cut out all the diffuse radiation, and you get a mirror off which a ray’s angle of reflection is precisely its angle of incidence. For rays of longer wavelength than short-wavelength visible light, the polishing need not be as fine. Use the radar emitter and receiver to test the different surfaces and find the best radar reflectors: since radar has a wavelength 60,000 times greater than light, a wire grid makes a ‘polished’ surface.