A High Frequency Inverse Scattering Model to Recover the Specular Point Curvature from Polarimetric Scattering Data

摘要

Based on the time-domain first order correction to the physical optics current approximation, a relationship between the phase factors of the polarimetric scattering matrix elements and the principal curvatures at the specular point of a scatterer is established. The above phase-curvature relationship is tested by applying it to theoretical as well as experimental backscattering data obtained for a prolate spheroidal scatterer. The results of these tests not only determine the acceptability of the phase-curvature relationship, they also point out the range of kb values over which the first order correction to the physical optics currents is valid, and which serves as a compromise range between the high frequency condition required by the curvature recovery model and the drawback to lower frequencies required to prevent critical magnification of measurement errors. Another curvature recovery equation is derived by transforming the linear polarization basis to the circular polarization basis. The curvature recovery model is poven to satisfy the image reconstruction identities of invariant transformation. A scattering ratio is defined and its behavior is investigated at high frequencies. Its plot on the complex plane provides a simple way to help judge the accuracy of polarimetric scattering measurement, regardless of whether a linear or a circular polarization basis is used.