Contra-Directional Ridge Waveguide Couplers: Design and Applications

This article presents novel wideband contra-directional couplers based on single conductor ridge waveguide, and their applications. The couplers exhibit wide bandwidths and tight coupling while occupying very small volume due to the compactness of ridge waveguides. The methodology to design the couplers is presented. It is inspired by the even and odd modes used to design TEM coupled lines couplers but implemented with TE modes in this novel approach. The design starts with designing the coupling section in a quadruple-ridge waveguide that supports two independent even and odd TE modes. Proper choice of the cross section allows the designer to achieve the required impedance levels for the required coupling values. An S-band proof of concept prototype of a single coupler was synthesized, fabricated, and tested, demonstrating excellent measured results without any tuning. The couplers can be exploited in versatile applications, such as power sampling, beamforming, or high-power combiners. As an additional proof of concept design, a C-band three-way combiner was also designed and tested, showing the potential of the novel coupler for different applications.