An Improved Two-Scale Model for Electromagnetic Backscattering From Sea Surface

Based on composite rough surface and stochastic multiscale models, an improved two-scale model (TSM) is proposed. Different from the classical TSM, the proposed method adopts the integral equation method (IEM) to replace the small perturbation method (SPM) for calculating the contribution from small-scale roughness. Kirchhoff approximation (KA) is still kept in the model to calculate the contribution from large-scale roughness. Because the IEM has wider application range than the SPM, the proposed model exhibits a higher accuracy and has a wider application range in terms of sea surface roughness compared with the classical TSM. Usually, the classical TSM is sensitive to the cutoff wavenumber. The proposed model adopts an adaptive cutoff wavenumber instead of choosing a cutoff wavenumber in the classical TSM. The effectiveness of the proposed model is demonstrated through comparisons with the simulation results of multilevel fast multipole algorithm (MLFMA) and the measured results. Different roughness at different frequencies is analyzed as well.