Application of the Eigenmode Transformation Technique to the Analysis of Open Guiding and Radiating Structures

The eigenmode transformation technique which has been successfully applied to the analysis of inhomogeneously filled shielded waveguides containing metal inserts is shown to be capable of dealing open waveguides if a suitable absorbing material backing an artificial shielding is used to account for radiation effects. A simple model of plane waves is employed to find an optimum permittivity profile of the absorber. The eigenmode transformation technique is then used for the analysis of some radiation and discontinuity problems with open boundaries, namely the discontinuity between a parallel plate line and a half space, the radiation of a current source above a grounded dielectric sheet and a microstrip patch antenna. The suggested method is validated by comparison to other methods as well as measurements.