SUB-GRIDDING FDTD SCHEMES

Abstract

Local meshing or sub-gridding has been advocated by a number of authors as a way of increasing the spatial resolution of the finite difference time domain method (FDTD). In this paper we show how to use supraconvergence to analyze the error in a simple sub-gridding strategy in two dimensions. We also analyze the spurious reflection that occurs at an interface between two grids for the standard FDTD scheme, for simple subgridding method and for another subgridding scheme employing linear interpolation. The overall order of convergence of the reflection coefficients is the same for all the methods, but the linear scheme has a lower amplitude spurious transmitted mode compared to the simple subgridding scheme.