When a surface is illuminated by a radar beam, a portion of the energy is reflected back to the antenna (‘specular reflection’). A further portion is scattered back in the same way as light is scattered from non-reflective surfaces. The proportion scattered is controlled by factors such as the roughness and dielectric properties of the surface, and the wavelength of the incident beam. Acoustic signals used to study atmospheric waves are also subject to backscatter; the amount is calculated by comparing the strength of the transmitted signal with that of the received signal after allowing for attenuation and absorption of the signal by the medium through which it propagates.
Subjects: Earth Sciences and Geography.