Scattering by truncated lossy layers: a UAPO based approach

This paper proposes a solution for predicting the electromagnetic field diffracted by the edge of a lossy dielectric layer when illuminated by a plane wave at oblique incidence. The starting point is the introduction of electric and magnetic equivalent surface currents in the radiation integral. A physical optics approximation is used for such currents, where results are expressed interms of there flectin and transmission coefficients of the corresponding infinite structure. A useful approximation and a uniform asymptotic evaluation of there resulting integral allow one to obtain the three-dimensional diffraction coefficients. These are given interms of the standard transition function of the uniform theory of diffraction. The effectiveness of the proposed technique is assessed via comparisons with FDTD simulations. Due to the peculiarities of this approach, it can be properly extended to the analysis is of diffraction phenomena related to a large class of penetrable structures of practical interest