Compact Rx/Tx channel duplexer with tuning capability for integration in a 26GHz high capacity short haul radio equipment

A novel Ka-band Rx/Tx channel duplexer design with tuning capability is established for the 26GHz band. Thus, only a single hardware is necessary to serve all duplex channel combinations of the overall radio frequency band - a prerequisite for large scale low cost unit production. The applied filters consider optimal tailored transfer functions with transmission zeros, realized with compact planar overmoded TE₁₀₃ cavity structures to accommodate the extreme rejection demands while maintaining low insertion loss. A further design aspect has been easy integration and interfacing into the waveguide subsystem of the radio equipment. The complete duplexer structure has been designed using a mode matching based CAD. To satisfy the stability of the responses for the given outdoor environmental conditions it has been realized from silverplated INVAR sheets - a technique supporting the low cost issue. Good agreement of computed and measured results and the successful testing of the tuning capability verifies the design.