A locally conformal finite difference time domain (FDTD) algorithm for modeling 3-D objects with curved surfaces

In a recent communication (Dey et al., 1997), the authors have reported a simple yet accurate technique for the FDTD analysis of curved 2-D PEC bodies using a locally-conformal grid. In this approach, the H-field is assumed to be located at the center of a Cartesian cell regardless of whether it is empty, or partially-filled with a perfect conductor. In this paper, we extend this technique to the three-dimensional cases and illustrate its application by investigating the resonant frequencies of a spherical cavity for which we have access to analytical data. We demonstrate that the results generated by the proposed algorithm are far more accurate than those obtained with the staircased-FDTD method.