A subgridding scheme using hybrid one-step leapfrog ADI-FDTD and FDTD methods

A novel subgridding scheme that hybridizes the recently developed unconditionally stable one-step leapfrog alternately-direction-implicit finite-difference time-domain (ADI-FDTD) method and the conventional finite-difference time-domain (FDTD) method is proposed. The conventional explicit FDTD method is applied to coarse mesh regions while the leapfrog ADI-FDTD method to locally subgridded mesh regions. The difference between the proposed subgridding scheme and the existing ones lie in the fact that only spatial interpolation of fields is required at the interface between coarse and subgridded meshes. As a result, computational efficiency is improved while numerical stability maintained. Both stability and efficiency are verified through numerical experiments in simulating a substrate integrated waveguide.