Scattering and depolarization by rough surfaces near grazing angles - Full wave solutions

Employing the full wave approach to rough surface scattering, the apparent singularity in the physical optics and perturbation expressions for the scattered fields is not encountered. It is shown that the full wave expression for the far fields vanishes in a continuous manner as the observer moves across a shadow boundary. Precise criteria are set forth for near grazing angles where uniform plane wave excitations cannot be assumed. Comparisons between the full wave and the physical optics and perturbation solutions are made. Because the full wave solution is shown to bridge the gap between the physical optics and perturbation solutions, it accounts for both specular and Bragg scattering. It is shown that the full wave solutions satisfy reciprocity, duality, and realizability relationships in electromagnetic theory and that they are invariant to coordinate transformations.