A Subgridding Scheme Based on the FDTD Method and HIE-FDTD Method

To reduce the computer memory and time of the finite-difference time-domain (FDTD) method when the problems are simulated with fine structural features, the subgridding scheme that applies higher resolution only around critical areas is often used. In this paper, a new subgridding scheme is proposed which is based on the hybrid implicit-explicit finite-difference time-domain (HIE-FDTD) method and FDTD algorithm. The field components in fine local grids are updated using the HIE-FDTD method, and in the coarse main grids conventional FDTD method is utilized. Due to the weakly conditional stability of the HIE-FDTD method, the technique achieves the same time marching step in the whole domain as employed in the coarse FDTD scheme, and the need for the temporal interpolation of the fields in the fine grids is obviated, hence, the hybrid HIE-FDTD subgridding scheme is less time consuming and easy to implement. Practical application of hybrid algorithm in the simulation of the shielding effectiveness of an enclosure is reported.