Abstract: This paper proposes a novel orthomode transducer (OMT) based on using composite right/left-handed (CRLH) transmission lines (TLs), which accomplishes the same function at two different arbitrary frequencies. Theory, synthesis procedure, and implementation of the dual-band OMT are presented. First, the CRLH TL theory is given, and a microstrip implementation of a CRLH TL is described. A novel structure of the OMT by replacing the general pure right-handed (RH) TL branches with the CRLH TL branches is then proposed. The dual-band OMT exhibits return loss larger than 6dB in the first band and 17dB in the second band, phase difference , and amplitude imbalance less than 0.5dB. The research also finds that the jumpers have a remarkable effect on the return loss and the return loss increases as the heights of jumpers decrease.
Keywords: orthomode transducer; composite right/left-handed transmission lines; dual-band; jumper

References
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