Scattering and Depolarization by Rough Terrain and Sea - A Unified Full WaveApproach

摘要

The principal results are summarized here. (1) Two separate approaches aredeveloped to account for multiple scatter from rough surfaces. (2) In the high frequency limit shadowing is accounted for by limiting the angles of incidence and scatter to less than 90 deg. (3) The random rough surfaces are often characterized by Gaussian surface height and slope probability density functions. (4) To determine the rough surface cross sections, the random rough surfaces need to be characterized by their joint characteristic functions. (5) The medium below the rough interface is characterized by its complex permittivity and permeability. (6) To make the problem of evaluating the scattering cross sections of random rough surfaces more tractable, it is assumed that the rough surface heights and slopes are statistically uncorrelated. (7) The observed phenomena of enhanced backscatter from very rough surfaces (including particles with rough surfaces) has been examined in some detail. (8) Investigations were conducted to determine the scattering cross sections of rough surfaces modified by the presence of oil slicks, ship wakes, swells and other anisotropic surface features. (9) For the vector problem of electromagnetic scattering by two dimensional rough surfaces, the excitations considered are in general elliptically polarized waves. (10) In the past several attempts have been made to obtain experimental validation of the numerical/analytical results based on the full wave approach. The full wave solutions, with the singly and multiply (two bounce) contributions accounted for in the analyses of scattering from very rough surfaces, provide an analytical/physical interpretation of the observed enhanced backscatter at both normal and oblique incidence. (jhd)