Efficient hybrid spatial and spectral techniques in analyzingplanar periodic structures with nonuniform discretizations

A new efficient technique for analyzing planar periodic structures with arbitrary unit cell geometry rendered in a nonuniform discretization is proposed in this paper. The mixed potential integral equation is solved by the method of moments in conjunction with the Rao-Wilton-Glisson triangular discretization. The convergence of computing each element in the impedance matrix is accelerated using Ewald's method for contributions of quasi-dynamic and complex images and the lattice-sum method for the surface-wave contribution. Numerical efficiency and accuracy of this hybrid method are compared with the spectral-domain method