Accurate absorbing boundary conditions for the FDTD analysis of H-plane waveguide discontinuities

A brief discussion about absorbing boundary conditions is presented which focuses on the FDTD modelling of waveguide discontinuities. An accurate first-order ABC is developed and tested, and also second-order ABCs are designed and discussed, which are used with a nonmonochromatic excitation. Finally, these ABCs are used in the study of some common H-plane waveguide discontinuities: a waveguide-type dielectric filter and an open-ended flanged parallel plate waveguide.