Prism-Based DGTD with a Simplified Periodic Boundary Condition to Analyze FSS with D_2n Symmetry in a Rectangular Array under Normal Incidence

In this letter, we develop a prism-based discontinuous Galerkin time-domain (DGTD) algorithm with simplified periodic boundary conditions (PBCs) to analyze infinite doubly periodic frequency selective surfaces (FSS). Most FSS structures contain patterned planar conductive layers and supporting dielectric layers. These layers are very thin compared to the wavelength. Therefore, general tetrahedral discretization of space will unnecessarily increase the number of mesh elements, as well as the number of unknowns. Instead, we propose using prismatic elements, which are more optimal for planar structures, resulting in less unknowns, less memory usage, and higher efficiency. The accuracy of the proposed prism-based DGTD method is verified by numerical examples compared with commercial software packages. Moreover, the CPU and memory costs are also compared, demonstrating clear advantages of the proposed prism-based DGTD method.