Synthesis of wideband waveguide diplexers

A design strategy for high-performance waveguide diplexers is presented in this paper. This technique directly provides the geometry of the two filters starting from the desired frequency response expressed in polynomial form. The dispersive mutual loading effect of the two filters and the various junctions as well as the losses and the multimodal interaction are kept into account. A diplexer with two 7-cavity filters in double-ridge waveguide with a -50 dB transition bandwidth of 1.4% and a return loss of 23 dB is reported.