The Development Of Millimeter-wave Diplexer

The millimeter wave diplexers used in the Ka-band satellite communications are investigated. These diplexers are of high working frequency, narrow passband and high selectivity, which demands the channel filters good performance.Two type microwave bandpass filters are applied to meet different bandwidth requirements. The filters of the 2% relative bandwidth is realized by ^ /4 coupled waveguide filters, whereas the ones of 1% relative bandwidth utilizes E-plane septum mounted in the wavefuides.Very compact diplexers are achieved by different configurations individually. The A- /4 coupled waveguide filters are directly connected to the H-plane Tee junction. And the E-plane septum filters realize millimeter-wave E-plane integrated circuit diplexers.The tuning process is necessary to better the filters' characteristics, as well as the matching between the waveguide filters and Tee junction, both of which are arisen from the manufacture errors. The measurement results demonstrate that the diplexers have low insertion loss and high channel segregation.The design methods, simulation procedures and measurement results are described in detail in this paper.