Stabilised CPFDTD algorithm for the analysis of arbitrary 3D PEC structures

The use of the contour path finite difference time domain (CPFDTD) method with locally distorted contours is well known to give accurate results for curved metal structures. The numerical stability of this scheme is, however, not guaranteed and this can pose problems, especially in the analysis of closed resonant structures. In addition, the generation of the distorted mesh is itself not a trivial task. we present a modification to the three-dimensional scheme which, without sacrificing accuracy renders it numerically stable, robust and easy to generate. A step-by-step procedure is given whereby the distorted mesh can be automatically generated for any desired metal structure. The accuracy of the modified scheme is demonstrated for the analysis of a circular cylindrical resonant cavity which is tilted with respect to the Cartesian FDTD mesh