Improved locally distorted CPFDTD algorithm with provable stability

The contour path finite difference time domain (CPFDTD) method has been shown to give accurate results for curved metal structures. However, the numerical stability of this scheme is not guaranteed and significant skill is required to generate an appropriate grid. The authors present a modification to the two-dimensional CPFDTD method which ensures stability and which permits simple generation of the locally distorted grid. The accuracy of the scheme is demonstrated through calculation of the resonant frequencies of circular cylindrical resonators