Integrated Wideband Multiplexer Design for Multiple-Use SATCOM/Terrestrial Terminals

A novel wideband multiplexer is introduced as a communications equipment solution in order to provide simultaneous operation of satellite and terrestrial services in the dedicated $K$/$Ka$ frequency bands (passbands ranging from 19.5 GHz to 30.5 GHz). Advanced RF filtering techniques are applied in order to accommodate a compact multiplexer design while maintaining low insertion loss and high rejection demands up to 33 GHz. Due to the overall wide bandwidth and the demanding requirements for the assigned three operational bands, different filter types have been employed. Thus, the multiplexer considers the combination of filters with rectangular, evanescent combline, and conductor-loaded resonator types. The multiplexer relies on the direct branching approach, i.e., all filters are connected to a central (star-junction) waveguide branching region. This region exhibits a reduced waveguide size to suppress interference by higher order modes. For a verification of the approach, WR34 waveguide interfaces have been considered at all ports for prototype design, however, the design can be well adapted for integrated equipment solutions with associated direct interfaces. Accurate coincidence of analyzed and measured performance of the prototype demonstrates the validity of the special approach. Moreover, additional simulations are provided as an outline for terminals with specific industry demands.