Study of the effect of the meshing by blocks in the finite difference-time domain method

In the field of microwaves, the finite difference-time domain method gives a precise description of the electromagnetic field close to the discontinuities. An accurate analysis of the variations of the electromagnetic field components in the regions where they have very fast variations requires a smaller spatial discretization of the differential equations. The introduction of these blocks creates nonphysical discontinuities which produce “numerical noise” (or “spurious modes”). In this paper, we describe the effects of these changes in the mesh size and we propose an original solution in order to decrease and possibly to cancel these parasitic effects