Radar polarimetry applied to scattering from irregular layered media

Abstract

Full-wave expressions are derived for the Mueller matrix elements that provide a complete polarimetric characterization of the electromagnetic fields scattered from irregular layered media consisting of dielectric coatings over dissipative substrates. The upper interface between free space and the coating material and the substrate is a two-dimensionally random rough surface, and the bottom interface between the substrate and the coating material is a planar surface. Each term of the full-wave expression for the vertically or horizontally polarized electromagnetic fields scattered by the irregular stratified media is shown to have a clear physical interpretation. The full-wave solutions satisfy the reciprocity and duality relationships in electromagnetic theory and are invariant to coordinate transformations. The expressions for the scattered fields reduce to that for the specularly reflected wave when the layered structure is a parallel stratified medium. The Mueller matrix or the modified Mueller matrix are measurable quantities that are used to relate the scattered Stokes vector to the incident Stokes vector. The elements of these matrices are related to commonly measured quantities in remote sensing and in ellipsometry. The analysis is relevant to problems of communication in irregular stratified media, remote sensing of irregular stratified media, and interpretation of ellipsometric data obtained from layered media.