Method of the FDTD analysis for periodic waveguide

摘要

The efficient FDTD algorithm for analyzing the periodic waveguide in an arbitrary shape was shown. The method is based on Floquet's theorem. The analysis sample is the parallel-plate waveguide of lossless and is nonradiation. First, the propagation constant of the waveguide was assumed. Next, the region of the waveguide was made discrete in time and space, and field equations were deduced. Then, the transitional electromagnetic fields were calculated with the FDTD scheme. After the Fourier Transformation of the field, the signal frequency for the propagation constant was decided. As a calculation example, it was calculated the propagation characteristic for the corrugated waveguide. And, the k-β characteristics were obtained. In addition, it was compared with the result by the modal expansion method. The two results agreed well, and the effectiveness was confirmed. For the discretion in direction of propagation, the calculation is possible for this technique only in 1 period. And, this technique demonstrates the power in order to reduce the memory and calculation time of the computer.