Ku Band Waveguide Diplexer for Satellite Communication Links

The proposed diplexer is based on two filters with iris discontinuities on the H-plane junction waveguide. Both filters are operated in the Ku band. The Tx band is centered at 12.15 GHz, and the bandwidth is about 500 MHz with a good match better than 30 dB, while the Rx filter central frequency is around 14.25 GHz, with a bandwidth of 1.05 GHz and the matching level is also better than 30 dB. After having designed both Rx and Tx filters, we will combine these two filters together by a common junction to create the final structure of the waveguide diplexer. The junction used consists of three WR75 standard waveguide ports. The simulated results show great agreement between CST-MWS and Mician mu Wave Wizard software. The return losses are better than 15 dB in the entire transmission and reception bands [Tx/Rx], the insertion losses are less than 0.12 dB, and the isolation between the two Rx/Tx ports is in the order of 80 dB. The final structure provides good electrical and mechanical performance without using additional lossy and bulky materials such as resonators or discontinuities, which limit the maximum transmittable power and increase the cost of the device.