The application of a simple absorbing boundary algorithm to cylindrical waveguide

The authors present the implementation of a very simple, yet very effective, plane absorbing boundary algorithm for a rectangular waveguide operated in the TE/sub 10/ mode analyzed with the FDTD (finite-difference time-domain) method. This absorbing boundary produces an amount of reflection smaller than 0.02% at the tuning frequency, works for arbitrary incidence angle, and is very local, meaning that the algorithm requires the knowledge of the field values at grid points located only one space increment away from the absorbing boundary. The algorithm was developed from physical understanding of the wave propagation on a discrete mesh, with the concepts of phase and group velocities. The efficacy of the absorbing boundary is demonstrated by measuring the percentage of reflection in the frequency domain.<
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