Scattering computation of slightly rough Gaussian surfaces by Kirchhoff approach with harmonic extraction analysis

The problem of electromagnetic wave scattering from rough surfaces has been the subject of intensive investigations over the past several decades for its applications in a number of important remote sensing implementations. For slightly rough surfaces that the radius of curvature of surface is bigger than the wavelength, the Kirchhoff method is the most commonly used approach. In this paper a new way for scattering computation from rough surfaces is introduced. Here Kirchhoff approach is applied for considering the electromagnetic wave interaction with slightly rough Gaussian surfaces. Fourier series of rough Gaussian surface is used for extracting the strong harmonics of the surface. Then by using the Kirchhoff formulation for periodic surfaces, scattering coefficient is computed. It is shown that by strong harmonics extraction of the rough surface, the acceptable results could be attained. This method could be useful in ray tracing. Asphalt surfaces are simulated by this method in millimeter-wave band. The results are also validated with the method of moments.