STATISTICAL WAVE THEORY FOR SCATTERING FROM A RANDOM MEDIUM LAYER OVER A TWO-SCALE ROUGH SURFACE

摘要

We have presented in this paper a statistical wave-based analysis for the combined scattering from a random medium layer with a two-scale rough boundary. Unlike our earlier approach [Mudaliar, Waves Random Media, 11, 45] which is suitable only for slightly rough boundaries, the approach described in this paper is applicable to a variety of rough boundaries, including those with fluctuations of large amplitude. We have used the concept of generalized Green's functions, where the various coefficients are replaced by surface scattering operators. The tasks of averaging over volumetric and surface fluctuations are carried out separately. Following this procedure we calculated the mean Green's functions, and showed how they depend on surface and volumetric statistics. We used the Wigner transform to convert Bethe-Salpeter equation to an integral equation for radiant intensities. The normalized scattering cross sections are calculated using the radiant intensity of up-going waves at the top boundary. Based on a first-order solution we have presented a numerical example to illustrate the roles of volumetric and surface fluctuations on bistatic scattering cross sections.