Study On The Electromagnetic Scattering From The Gaussian And Non-Gaussian Rough Surface Using The Small Slope Approximation

In this paper, the fundamental theory of electromagnetic scattering from the rough surfaces is introduced, different methods of electromagnetic scattering from the rough surfaces include the Kirchhoff approximation and the small perturbation approximation are discussed. The derivation of the small slope approximation from the rough surfaces is examined in detail, this theory gives a systematic expansion that can be interpreted as series in generalized surface slope. The bistatic scattering cross sections under the one- and two-dimensional random conducting/dielectric rough surfaces with Gaussian spectrum distribution are obtained. The results are also compared with those obtained from the Kirchhoff approximation with shadowing effect considered and the experimental data, it is found that the small slope approximation is more accurate with grazing angle incidence and the numerical results show good agreements with the experimental data. It is also found that the implementation of small slope approximation is easy and adapted to the microwave backscattering models from the sea surface. Finally, the derivation of the small slope approximation from the non-Gaussin rough surfaces is examined. The skewness, the deviated peakness functions and the scattering cross sections for the non-Gaussian random surfaces are derived, the comparison of the backscattering cross section for the Gaussian and non-Gaussian rough surface by the small slope approximation are also given and analyzed.