Ieee antennas and wireless propagation letters vol:2 pages:281-284
In this letter, a new way for the termination of periodic waveguides in integral equation like simulation techniques is introduced. Exploiting the complex coordinate interpretation of a Perfectly Matched Layer (PML), we can terminate a periodic waveguide by adding a couple of periods in the complex plane. If the waveguide enters the complex plane in a smooth way, the reflections caused by the periodicity disturbance are very low and at the same time one achieves a significant absorption. This idea is applied to a 2-dimensional electromagnetic crystal waveguide structure. The validity of our approach is demonstrated by comparison with a rigorous method based on the exact calculation of the excitation coefficients of the eigenmodes in the waveguide and by comparison of a more complex example (a two-channel multiplexer-demultiplexer) from literature.