An Orthomode Transducer (OMT) Using Magic Tees for Improved Performance, Manufacturing, and Integration
Doug W. Henke, Dave Atherton, Ivan Wevers, Adam S. Densmore · IEEE Transactions on Microwave Theory and Techniques · 2025
We present an orthomode transducer (OMT) design based on the turnstile junction that provides balanced signal outputs, suitable for either linear or circular polarization. The OMT uses magic tees for recombination, which has the advantage of terminating higher order modes that could arise from fabrication and assembly uncertainties. Trapped higher order modes can become even more troublesome when greater waveguide integration is used, such as in focal plane array layouts. Generally, integrating magic tees within a waveguide network for differential or in-phase power division is advantageous because of their improved isolation, compared to simple T- or Y-junctions. A prototype OMT was fabricated, using magic tees and demonstrated increased waveguide integration using hole couplers. Hole couplers have been integrated for receiver calibration using noise injection. Measurements are shown for Q-band, spanning the band 5 receiver specifications for the next-generation very large array (ngVLA) radio telescope (30.5–50.5 GHz).