Polarimetric Two-Scale Model for the Evaluation of Bistatic Scattering from Anisotropic Sea Surfaces

Abstract

The Two-Scale Model (TSM) is a useful approach for the evaluation of scattering from rough surfaces. In order to model depolarization effects, TSM, in its original formulation, requires an average operation that calls for numerical integration, so strongly reducing the computation efficiency. However, in the last decade a method to analytically compute this average in closed form, named Polarimetric TSM (PTSM), was devised. More recently, the PTSM, originally applied to backscattering from statistically isotropic rough scattering surfaces, was extended to the case of anisotropic rough surfaces (A-PTSM), in order to compute backscattering from sea surfaces. Both PTSM and A-PTSM, as presented in previous work, only consider the monostatic configuration. Here, we extend A-PTSM to the more general case of bistatic scattering. In particular, we present the procedure to obtain all the elements of the bistatic polarimetric covariance matrix in closed form; we then present some numerical results with reference to the bistatic Normalized Radar Cross Sections (NRCS) in circular polarization basis, which are of interest for some recently proposed bistatic passive radar systems with GNSS signals of opportunity.