Multifrequency Waveguide Orthomode Transducer

This paper presents the design and development of a multifrequency probe-coupled orthomode transducer (OMT) using a circular waveguide as the primary waveguide and a rectangular waveguide as the secondary waveguide. Design is presented for a common OMT operating at 6.6, 10.65, 18, and 21 GHz using four cascaded circular waveguide sections with different cross-sectional dimensions. An innovative design technique is used to minimize the inter-port coupling and to maximize the power in the dominant mode to get the required radiation performance at all the frequency bands using a common radiating aperture. The simulated and measured parameters of the OMT and the horn fed by this OMT have been presented.