Implementation of the Split-Field Method for FSS Structures

A method for implementing the periodic boundary condition(PBC) in the finite-difference time-domain algorithm(FDTD) is presented. By using the split-field method, a set of auxiliary elements are introduced to realize the discretization of the Floquet-transformed Maxwell's equations with oblique incidence. The UPML equations for the split-field FDTD are also described. The method is applied to a doubly periodic infinite frequency selected surface (FSS) and numerical results are compared to authoritative solutions, demonstrating its validity and utility.