Circularly Polarized Bistatic Scattering From Sastrugi Snow Surfaces

Abstract

In this letter, we investigate the circularly polarized bistatic scattering from sastrugi snow surfaces at the $L$ -band (1.575 GHz) at different azimuthal angles. Comparisons of circularly polarized bistatic scattering are made between the likewise (left-hand circularly polarized transmitting and left-hand circularly polarized receiving or right-hand circularly polarized transmitting and right-hand circularly polarized receiving) and the counterwise (RL or LR). Numerical simulations show that the counterwise configurations are only preferred, in the sense of maximum received power, for randomly sastrugi surface, but not always so when the surface structure is double-layered, at which the likewise polarized scattering strength is comparable to, and at certain azimuthal angles it is even larger than, that of the counterwise polarized scattering. Physical mechanism of such a behavior is explicated by the phenomena of local Fresnel reflections. Results from this letter offer physical insights for bistatic sensing of layered snow surface. It is suggested that for microwave remote sensing of snow surface by bistatic signals (e.g., global positioning system), both transmitting and receiving polarizations in likewise and counterwise be adopted.