A 2-D Floquet boundary condition for time-domain finite element analysis of periodic geometries

In this paper, we outline a derivation for an absorbing boundary condition (ABC) that, when used with a recently developed FEM-TD formulation, is capable of effectively truncating the computational domain due to higher-order Floquet modes for electromagnetic simulations of infinite periodic structures in 2D. We demonstrated the accuracy of the new ABC, as well as indicating that the inclusion of this rather complicated ABC in the FEM-TD formulation appears to maintain stable time marching, even for a very large time step.