An impedance boundary condition for the efficient matched termination of waveguides in FDTD simulations

This Letter introduces a novel impedance boundary condition (IBC) for the matched termination of waveguide ports in finite-difference-time-domain (FDTD) simulators. It is based on approximating the wave impedance by a rational function over the frequency band of interest. To show the validity of the proposed IBC, the reflection coefficient of a wideband matched 90degrees H-plane corner in rectangular waveguide is computed. The results obtained, which are less than -45 dB over the whole waveguide band, are in good agreement with those obtained by a commercial finite-element simulator. (C) 2002 Wiley Periodicals, Inc.