• frequency domain;
  • TLM;
  • absorbing boundary conditions;
  • perfectly matched layer;
  • one-way equation;
  • matched waveguide


This paper investigates the absorbing boundary conditions for the frequency domain transmission line matrix method. Two approaches are presented, namely the perfectly matched layer (PML) technique and the one-way wave equation. Concerning the PML technique, two-dimensional and three-dimensional transmission line matrix (TLM) nodes, already used in time domain, are exploited in frequency domain where a rigorous formulation of these PML–TLM nodes is presented. In addition, two types of one-way wave operators are also transposed from time to frequency domain TLM approach: Taylor expansion and Higdon's boundary conditions. The simulation of a wideband matched load WR-28 rectangular waveguide is presented for validation. Excellent results are obtained with a very thin PML layer. Results concerning one-way operator techniques also show very good return loss performances. For instance, Higdon's boundary condition was extended beyond third-order approximation, and a return loss better than 160 dB was obtained. Copyright © 2013 John Wiley & Sons, Ltd.