FDTD Modeling of Finite Electromagnetic Source over Periodic Structure via a Spectral Expansion Approach

A novel three-dimensional (3D) time-domain method is proposed to model the interaction between finite size electromagnetic source over infinite periodic structure. The method is based on a periodic FDTD method in conjuncture with the spectral expansion of the finite electromagnetic source. Using this method, only a single periodic cell needs to be modeled in FDTD simulations. Several periodic structures are simulated by this proposed method. It is shown that this method can significantly reduce the required computer memory and CPU time.