Analysis of time domain modes in FDTD-Diakoptics

It is very important to choose proper time domain modes when microwave structures were analyzed by time domain Diakoptics. Two-dimensional Bessel functions are proper time domain modes in time domain Diakoptics. One-dimensional Bessel function expansion theorem was extended to two-dimensional, the completeness and orthotropic property of two-dimensional Bessel functions were proved. Based on the analysis of electromagnetic field distributions for such open microwave structures as coplanar strips, the zero and one order Bessel functions were proved to be the proper time domain mode functions. The results of this method and that of the finite difference time domain (FDTD) were compared and there is good agreement between them.