Diffuse reflection by rough surfaces: an introduction

In this introductory paper, we present with some details the (mathematically) simplest methods proposed to compute the electromagnetic field scattered by a rough surface separating two homogeneous media. These methods remain largely used both in propagation and remote sensing problems. The methods described in the paper are: – ometrical optics approximation, in which the wave is considered as a set of rays obeying the laws of reflection and refraction; all perturbation method, due to Rayleigh and Rice, in which the field is given as an expansion on a set of elementary harmonic plane waves, the coefficients of which are determined so as to satisfy the boundary conditions; rchhoff approximation, in which the field is given as an integral on the rough surface; in this method one needs to know some components of the field on the surface, and an approximation is substituted to the unknown true value. with a short discussion of some problems not adequately solved by these methods, namely self-shadowing, multiple scattering and some inadequacies of the Gaussian model for random surfaces. To cite this article: M. Sylvain, C. R. Physique 6 (2005).