Design of a wideband orthomode transducer

Abstract

The design of an offset ridge quad-ridged waveguide (QRWG) orthomode transducer (OMT) is presented. By offsetting one of the ridges in the direction of propagation, a much wider single mode operating bandwidth can be achieved than that achievable in a traditional symmetric QRWG OMT's. This wide single mode operating bandwidth ensures that no higher order modes are excited at the feeds of the OMT, which in turn eliminates unwanted resonances often observed in traditional QRWG OMT's. The performance of the OMT is similar to that of traditional types, with reflections below −20 dB and cross coupling below −40 dB across most of the desired 1.7∶1 bandwidth.