A Hybrid FETD Algorithm for Electromagnetic Modeling of Fine Structures

A novel hybrid finite-element time-domain (FETD) algorithm is proposed to solve electromagnetic modeling with fine structures. This algorithm is based on the unconditionally stable FETD (US-FETD) and the traditional FETD methods. The US-FETD is used in the subdomain containing all fine grids and parts of coarse grids adjacent to the fine grids. The traditional FETD is applied in the other subdomain. A compensation and correction scheme is used to update the fields on the subdomain boundary. The hybrid FETD can make the explicit time marching unconditionally stable with a uniform time step determined by the coarse grids in the entire computational domain. In addition, the unstable modes of the entire system in the hybrid FETD can be effectively obtained by solving the partial solutions of the eigenvalue problem in the US-FETD subdomain. In comparison with the US-FETD in the entire computational domain, the eigenvalue analysis costs less memory and time. Numerical results certify the high efficiency of the hybrid FETD.