Scattering and depolarization of electromagnetic waves from a slightly rough dielectric layer

Abstract

Scattering of a plane, horizontally polarized electromagnetic wave in any direction from a slightly rough, lossless layer is considered. The layer is rough on both sides and the medium below the layer is assumed perfectly conducting. Small-perturbation theory is used and first- and second-order results are obtained. It is found that waves scattered along nonspecular directions are intimately related to the Fourier spectra of the boundary surfaces of the layer. In addition to the familiar multiple scattering between layer boundaries, there is multiple scattering due to surface roughness. This was not intuitively expected since the roughness was assumed to be small.The phenomenon of wave depolarization is found to occur and to be present in all directions. In general, the depolarized scattered field components are of the first order except for scattering in the plane of incidence, where only second-order terms are present.Special cases of scattering from a single, slightly rough interface are also found.