Methods for the modelling of bistatic ground scattering - A literature review

The present review is partly based on a previous literature search [FOI Memo 02-2332]. It is aimed at compiling the different models describing bistatic scattering at rough surfaces and at investigating the basis of and the relations between them. The study does not cover all models but concentrates on the small perturbation method/model (SPM), Kirchhoff methods, the integral equation method (IEM) and the small-slope approximation (SSA). The purpose of the study is to find methods and models suitable for implementing target-ground interaction in RCS calculations. Presently IEM appears to be the approximate method able to handle the widest spectrum of roughness conditions. The study indicates that these methods are not well suited for handling grazing incidence or scattering. General methods for the handling of any rough surface in any scattering geometry are subject to research. Few studies compare models to measurements. In particular IEM and SSA have been neglected in this respect. Some comparisons have been made with "exact" numerical methods such as FDTD and MoM. In order to evaluate the methods treated in this report they should be implemented and compared with each other, experiments and possibly "exact" methods.