CURVATURE EFFECTS IN THE COMPOSITE MODEL FOR LOW-GRAZING-ANGLE ROUGH-SURFACE SCATTER

The conventional composite surface model used for calculations of rada r backscatter treats a large-scale surface component as an ensemble of tilted flat facets. This approach has limitations for low grazing ang les. In the paper we develop a new composite model that takes into acc ount the diffraction of an incident field on a curved, large-scale und ulating surface. It is shown that, whereas corrections related to curv ature effects are small for a steep incidence, those corrections for l ow-grazing-angle backscatter can be quite essential. Results of numeri cal simulations of radar backscattering cross sections for two polariz ations are presented. Scattering from a surface with one-dimensionally varying roughness is considered. We have studied the role of undulati ng surface slopes and curvatures in the behaviour of the polarization ratio and found regimes in which the curvature influence on this ratio is more pronounced.