Low-loss and lightweight on-board 20 GHz-band pill-box-type directional filter

An on-board channel multiplexer using pill-box-shaped TM310 travelling-wave cavities with high unloaded Q-factor has been developed in the 20 GHz band. The measured branching loss of a three-cavity filter is 0.27 dB at a resonant frequency of 19.99 GHz. The weight of the filter made of thin-walled super-Invar is 71 g. Its size is 4.5×4.6×5.1 cm.