A Comparative Performance Study of Absorbing Boundary Conditions in TLM and FDTD

C. Eswarappa and W. J. R. Hoefer

12th Annual Review of Progress in Applied Computational Electromagnetics, pp 302-309, Monterey, California USA, March 18-22 1996.


In this paper, a comparative performance study of Higdon's absorbing boundary conditions (ABCs) in TLM and FDTD under identical conditions (such as time step, excitation, etc.) is described. It has been observed that an ABC applied directly to the TLM voltage impulses absorbs better than the same ABC applied to the TLM total node voltages or FDTD field values. It has also been found that in a FDTD analysis, the damping factors have a greater influence on the stability than the way in which the absorbing boundary operators are discretized, while in a TLM analysis the opposite is true. Also, in a TLM analysis, the absorbing boundaries can be placed closer to a scatterer than in a FDTD analysis without affecting accuracy. These observations have been demonstrated by applying them to examples such as waveguides and high permittivity dielectric cubes.

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