Boundary-element analysis of planar circulators: a discussion on spurious solutions and their elimination

Some results on the application of the Boundary-Element Method to the computation of the scattering parameters of planar circulators also working in the region /spl mu//sub eff/<0 are presented. Spurious solutions are first pointed out, and two different ways to eliminate them are discussed. The analysis supports Schroeder's explanation of the appearance of spurious modes in integral equation techniques. Extensive numerical simulations are presented to validate the formulation proposed.<
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