Spectral analysis of left-handed rectangular waveguides with dielectric-filled corrugations

The spectral analysis of an infinite rectangular waveguide with dielectric-filled transverse corrugations is performed to investigate supporting backward waves in this structure. The corrugations act as a capacitive immittance surface which provides a suitable environment for left-hand propagation to occur in an undersized rectangular waveguide having an inherent shunt inductance of the evanescent transverse electric dominant mode. The analysis of the corrugated waveguide is based on Floquet´s theorem, where the problem is solved in terms of a unit cell; then Galerkin´s projection technique is applied to reduce the integral equation to the matrix form. The dispersion relation and the modal field expressions are derived and, for the special case of wall-to-wall corrugations with single current harmonic, rather simpler expressions are obtained. The effect of the different design parameters on the dispersion characteristics is studied with emphasis on the left-hand propagation band. Some representative field plots of the dominant mode of the corrugated structure are depicted. Sample results are compared with Ansoft High Frequency Structure Simulator (HFSS) and with an equivalent circuit model developed for the same structure. The results exhibit very good agreement.