Subgrid Surface Impedance Absorbing Boundary Condition for FDTD Method

Abstract

Previously, we designed an effective SIABC, which significantly reduces the thickness of the absorption boundary compared with the traditional PML boundary condition. The use of SIABC requires a long distance between the scatterer and the boundary, which increases the memory and running time of the program to a certain extent. The sub grid technology alleviates this problem by setting the area near the scatterer as a fine grid area and other areas as a coarse grid area, so as to reduce the number of grids to be calculated in the whole area. We build a simple two-dimensional model and apply sub grid technology for simulation. The simulated results are compared with those of different grid sizes. It is found that the simulation accuracy is basically the same as that of full fine grid, and the calculation time is greatly shortened. The results show that the combination of sub grid technology and SIABC is a promising FDTD simulation method.