DESIGN AND FABRICATION OF COMPACT AND HIGH PERFORMANCE C BAND OMT

This paper presents the design, simulation and fabrication of simple C band orthomode transducer (OMT)
machined in two identical parts for manufacturing easiness. This device offers compact size and high
electrical performance. The device consists of a common circular input port and rectangular ports for
horizontal and vertical polarization separation. The common port has a direct transition from circular to
rectangular waveguide for the through port coupling. The side port coupling is done via coupling slot and
waveguide transition. The design of the device utilises the concept of class I asymmetric based OMT and
intermediate truncated circular waveguide. The device is simulated and optimised in CST Microwave
Studio and the simulated results of the device are compared with the measured results. The measured
return losses of the both rectangular ports are better than 20dB, port to port isolation greater than 50dB
and cross-polarization discrimination better than 35dB.The measured results were in good agreement with
the simulated results.