Circular polariser for use in a gyro-travelling wave amplifier

A corrugated rectangular waveguide, commonly used in radio frequency antennas applications, was considered for use in a gyro-TWA experiment. This waveguide transducer produced broadband circularly polarised radiation in the Ka-band frequency range (26-40 GHz). Computer simulations, using computer simulation technology Microwave Studio^®, were carried out and predicted return losses exceeding 30 dB and a 6° phase variation for 20% bandwidth centred at 31 GHz. Comparison between experimental measurements and simulations showed good agreement. The performance of this polariser was also compared to that of a conventional elliptical converter. Owing to its broadband performance the authors consider some of the technical aspects of applying this component to a Ka-band gyro-TWA experiment.