Wideband hybrid diplexer using ridged waveguides

To develop a broadband diplexer to be used for the Ku band satellite communication earth station, a hybrid diplexer is proposed based on the branch waveguide directional coupler in which the main and auxiliary waveguides are ridged waveguides. The theoretical discussions and experimental results are described. First, the characteristics of the hybrid diplexer and those of the constituent components are expressed in terms of the scattering matrix so that the effect of the hybrid coupler is presented. Next, the characteristics of the branch waveguide directional coupler used as a hybrid coupler are studied theoretically. It is pointed out a broadband operation is possible by the use of ridged waveguides for the main and auxiliary waveguides. Further, using the transmit and receive diplexer for the Ku band satellite communication earth station as an example, the design and fabrication have been carried out to demonstrate the validity of the theoretical results.