Abstract:

According to the problem that there is not a unified guideline for the choice of the cutoff wavenumber for the classical two-scale model (TSM), an angular cutoff two-scale model is proposed, which is based on the local incident angle division to select the corresponding method for electromagnetic scattering calculation from rough sea surface. When the local incident angle is smaller than the restricted angle (approximately 20°), the Kirchhoff approximation (KA) is applied to evaluate the specular reflection, which dominates the total scattering in this region; the small perturbation method (SPM) is employed to deal with the diffuse reflection reigned by small roughness as the local incident angle is greater compared with the restricted angle. This new model takes advantage of the superiority of KA and the SPM respectively without dwelling on the tough question about how to choose the proper cutoff wavenumber for the classical TSM. Numerical evaluations for the influence of the wind speed, the polarization as well as the wind direction on the backscattering coefficient from randomly rough sea surface are investigated, the results are in good agreement with the experiment measured data. The validity of the proposed model is then obtained.