Macroscopic Dielectric Constant Model for Layered Media With Rough Surfaces

A macroscopic dielectric constant (MDC) model is proposed to describe the impact of a dielectric layered medium with two-layer rough surfaces (TLRSs) on 2-D electromagnetic scattering. The MDC model is based on the Kirchhoff approximation (KA) method to find an equivalence between the total fields on a TLRS and on a single-layer rough surface (SLRS). With this model, evaluating the scattering over a TLRS can be reduced to a simple SLRS scattering problem. The KA method is used in conjunction with the MDC model to calculate the bistatic scattering coefficients at different surface roughness conditions. The results are in good consistency with the values obtained using the method of moments. Extensive numerical results confirm that the MDC varies along the profile of the top surface as the surface roughness increases, and the variations in the surface roughness and medium depth can significantly affect the fluctuation and mean value of MDC.