A MLSD-SMCG METHOD FOR SCATTERING AND EMISSION FROM OCEAN-SURFACES WITH FULL OCEAN SPECTRUM AND LARGE RMS HEIGHTS

Accurate calculations of electromagnetic scattering and emission from ocean surfaces with large sizes and root-mean-square (RMS) heights are still a challenge for the fullwave numerical methods. The widely used sparse matrix canonical grid (SMCG) method is only efficient for small and moderate roughness surfaces. This is because of the limitation of approximations in the far-field expressions using Taylor series expansion. In this paper, a novel multilevel steepest decent-sparse matrix canonical grid (MLSD-SMCG) method is proposed to address this issue. The proposed approach is implemented with the method of moment (MoM) in solving the dual surface integral equations (SIEs). Simulation results are illustrated at L-band for ocean surfaces with wind speed up to 20 m/s. The entire spectra are involved to capture all scales of waves in simulations. Thus the surface root-mean-square (RMS) heights and lengths are up to 3.82 and 1024 wavelengths of 1.26 GHz, respectively. Numerical results indicate the proposed approach is computationally efficient and accurate. Energies in simulations are conserved to the order of 10−4 for ocean scattering and emission at various wind speeds.