A Switched-Huygens-Subgridding-Based Combined FDTD–PITD Method for Fine Structures

A new combined method is proposed for the problems containing fine structures. In this method, the precise-integration time-domain (PITD) method is adopted for fine structures with fine cells, and the finite-difference time-domain (FDTD) method is used for the rest with coarse cells. The fields in the coarse and fine cells are updated synchronously, which makes the proposed method fast. Besides, since the PITD method is only applied locally, the limitation of its large memory requirement is also alleviated. The numerical results confirm that this combined method has a fast computational speed.