Polarized Bistatic Scattering from a Spatially Anisotropic Rough Surface with Inhomogeneous Dielectric Profile

Abstract

This paper presents full polarization bistatic scattering from a spatially anisotropic rough surface with inhomogeneous dielectric profile modeled by a transitional layer as a function of depth. The spatial anisotropy is geometrically described by directional correlation function. Both linearly and circularly polarized scattering are investigated in light of azimuthal dependence, degree of anisotropy, and inhomogeneity. Numerical results show that the bistatic scattering in the incidence plane reveals strong dependence on degree of anisotropy near the specular direction. By comparison, for co-polarization, the linearly polarized scattering reveals stronger directional dependence, but the circularly polarized scattering tends to be more omnidirectionaland the scattering pattern seems to be “concentric circles” with the strong scattering locating at specular direction. For linear polarization, in virtue of dielectric inhomogeneity, the scattering pattern reveals several distinct features including: HH polarization increases significantly in the backward region but decreases slightly in the forward region; the forward and backward scattering of VV polarization are enhanced; HV polarization can be greater than VH polarization. For circular polarization, both LR and RR polarizations on the whole scattering plane are enhanced due to the inhomogeneity. As the transition rate increases from 6 to 12, for linear polarization, the HH polarized scattering coefficient increases 5 ~ 10 dB in backward region, and VV polarization increases 8 ~ 15 dB both in backward and forward region, that is, VV polarization is more sensitive to the transition rate; secondly, the HV polarization increases faster than VH polarization does; for circular polarization, both LR and RR polarizations are simultaneously enhanced but the difference between them shrinks. As the background dielectric constant increases, for linear polarization, the strong scattering of HH polarization tends to move to the forward region, while the VV polarized scattering coefficient reduces about 3 ~ 6 dB in forward region and is enhanced 5 ~ 10 dB in backward region; for circular polarization, both LR and RR polarizations are enhanced in backward region, but in forward region, LR polarization decreases and RR polarization increases.