Application of the small slope approximation for EM scattering from the rough sea surface

In this paper, the bistatic coefficient of the small slope approximation is derived in the polar coordinate. Based on the spectral model of Elfouhaily, the scattering coefficient of sea surface is calculated, and the theoretical results are compared with the experimental data and Kirchhoff approximation with and without shadowing effect considered. According to the small slope approximation theory, the dependence of the backscattering coefficient on the incident wave frequency and wind speed for different polarization is discussed. The results showed that theoretical results are consistent with experimental data for backscattering case. In the case of the bistatic scattering, the result calculated by the small slope approximation are accurate, especially for large scattering angle, and the backscattering scoefficient increases with increasing of incident wave frequency and wind speed.