RE-EXAMINATION OF RADAR TERRAIN BACKSCATTERING AT NADIR.

Abstract

The theoretical behavior of nadir specular and diffuse radar backscattering from rough terrain is reexamined. Terrain is modeled as a random rough surface in the Kirchhoff approximation. The relative significance of specular (coherent) and diffuse (noncoherent) radar backscattering is compared in terms of the antenna system parameters (beamwidth, height, and frequency) and rough surface statistics. It is found that in the case of a high-altitude (space or airborne) radar, the ratio between coherent and noncoherent terrain backscatter is independent of the altitude of the radar platform. A possible explanation is suggested for the anomalous radar backscatter observed in the Skylab S-193 altimeter experiment.