Application of physics-based two-grid method and sparse matrix canonical grid method for numerical simulations of emissivities of soils with rough surfaces at microwave frequencies

The simulations of emissivities. from a two-dimensional (2-D) wet soil with random rough surfaces are studied with numerical solutions of three-dimens ional (3-D) Maxwell equations. The met soils have large permittivity, For m edia with large permittivities, the surface fields can have large spatial v ariations on the surface, Thus, a dense discretization of the surface is re quired to implement the method of moment (MoM) for the surface integral equ ations, Such a dense discretization is also required to ensure that the emi ssivity can be calculated to the required accuracy of 0.01 for passive remo te sensing applications,It has been shown that the physics-based two-grid m ethod (PBTG) can efficiently compute the accurate surface fields on the den se grid. In this paper, the numerical results are calculated by using the P BTG in conjunction with the sparse-matrix canonical grid method (SMCG), The emissivities are illustrated for random rough surfaces with Gaussian spect rum for different Soil moisture conditions. The results are calculated for L- and C-bands using the same physical roughness parameters, The numerical solutions of Maxwell's equations are also compared with the popular H and Q empirical model.