A COMPARISON OF 2 CONFORMAL METHODS FOR FDTD MODELING

Two conformal finite-difference time-domain (FDTD) methods are conside red, the contour path (CPFDTD) method of Jurgens st at [4] and the ove rlapping grid (OGFDTD) method of Yee et al. [6]. Both TE and TM scatte ring from a two-dimensional (2-D), perfectly conducting circular cylin der are used to test the accuracy of the methods for curved surfaces. Also, TE and TM scattering from a 2-D, perfectly conducting rotated sq uare cylinder are used to test the accuracy for corners and edges. It is shown that the conformal method proposed by Yee et al. provide sign ificant improvement in accuracy over the original FDTD algorithm for m ost of the geometries studied in this paper. However, implementation b ecomes more difficult as geometries become more complex. The conformal method proposed by Jurgens st al. provide significant improvement in accuracy as well for most of the geometries studied In this paper. How ever, improvement does not occur for the TM case when the square cylin der is not aligned properly with the grid. Implementation of the CPFDT D method is relatively straightforward. For the majority of the cases studied, the OGFDTD method is more accurate than the CPFDTD method.