Channel multiplexers for broadcast satellite transponders in the 12 GHz band

In order to separate the input and output signals of canonical dual-mode filters used as input multiplexers in broadcasting via satellite, a new type of configuration, i.e., an orthomode T-shaped junction suitable for waveguide manifolds, is presented. To reduce the insertion loss of the filters used for output multiplexers, several methods such as the use of cylindrical TE-113 resonant-mode cavities, the optimization of the coupling apertures, and careful selection of tuning-screw materials, are applied. Finally, the multiplexers are formed into a small, lightweight manifold multiplexer, i.e., bandpass filters for each channel are attached to a common waveguide.