Numerical analysis of finite frequency selective surfaces

Results are presented of an analysis of a finite frequency-selective surface (FSS). The analysis is different from previous analyses since it eliminates the need for a relative convergence criteria, though it does not prove that relative convergence is not necessary to obtain the correct answer. In this analysis, through the proper choice of basis functions, all integrations and summations are bound and therefore can be continued until convergence is obtained. Several numerical techniques are used to speed the evaluation of integrals that are encountered in the formulation. The particular geometry analyzed is the one-dimensionally finite (infinite in the other dimension) FSS with three and seven patches in the finite direction. In general the patches can be any shape. For the purposes of this analysis, they are always rectangular and assumed to be geometrically and physically the same. Results are plotted for a patch size of 1.27 cm*0.127 cm in a square lattice of 1.78 cm*1.78 cm. The incident electric field is parallel to the long dimension of the patch. Angles of incidence presented are measured from the normal.<>