CHARACTERISTICS OF QUAD-RIDGED COAXIAL WAVE-GUIDES FOR DUAL-BAND HORNAPPLICATIONS

Circular coaxial quad-ridged waveguides find application in the design of broadband diplexers for the dielectrically loaded, ultrawide, dual -band horn. The three basic structures, where the four ridges are plac ed symmetrically on the inner conductor, on the outer conductor or on both conductors of the coaxial waveguide, are analysed using a modifie d Ritz-Galerkin method. To find the optimum configuration, the cutoff wavenumbers of the first two (effective) dominant modes for each of th ese structures, from which we deduce the bandwidth characteristics, ar e calculated and compared. The aim is to obtain the preferred coaxial ridged structure in terms of broad bandwidth and ease of fabrication.