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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 90° 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. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 151–155, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10400 [ABSTRACT FROM AUTHOR]

At the pre- and post-processing stages of a finite-difference time-domain (FDTD) simulation, important tasks are carried out that require knowledge of the port data (propagation constants, fields, impedances, and so on) of the problem structure. This paper introduces a 2D finite-difference frequency-domain (FDFD) eigenvalue formulation specifically tailored for the computation of port data to be used in conjunction with the 3D-FDTD method. A key feature of the proposed FDFD scheme is that it leads to the same numerical dispersion equation as that of the 3D-FDTD method. This means that, for a given frequency, the numerical propagation constants and mode patterns calculated by the two methods are identical. This is desirable for preserving the accuracy of the FDTD simulation. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 1–3, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20704 [ABSTRACT FROM AUTHOR]