Ka-Band 3-D-Printed Wideband Groove Gap Waveguide Orthomode Transducer

An orthomode transducer (OMT) that falls into the twofold symmetry category is designed at the Ka-band with 33.33% bandwidth. Groove gap waveguide (GGWG) technology is adapted to implement the design due to its suitability for millimeter-wave (mm-wave) frequencies as electrical contacts between different parts are not necessary. Moreover, two transitions are deployed to broaden the operating bandwidth. The first transition is GGWG to WR-28 standard waveguide, which also acts as a power combiner. The second transition is placed between two layers of GGWGs. This new OMT consists of two main sections, the OMT core section, and the assembly section of different parts. Each section is investigated and simulated separately; then the whole structure is simulated to validate the performance. A prototype is built using 3-D-printing technology with copper-electroplated surfaces. A back-to-back measurements technique indicated matching and isolation level better than 12.5 and 25 dB, respectively, for both polarizations over the entire band. Nevertheless, the insertion loss has an acceptable level over such bands.