Compact four-port rectangular waveguide switches based on simple short circuit loads

Four-port rectangular waveguide switches presented in this paper are based on alternating short and open circuit loads in the waveguide path. The switches are made up of four waveguides connected by sections of ridge waveguides where simple short-circuit loads can be activated to control the signal paths. The proposed concept eliminates the need to use bulky rotary mechanisms to provide path switching. The device layout is very simple and is also kept very compact. The concept is presented for C-, R- and T-type switches, based on rigorous full-wave simulations with the model for the short taken into account. An experimental Ku-band prototype for the T-type case (the most complex case involving three states) is built and measured. The experimental performance shows a return loss better than 23 dB from 13 to 14.5 GHz and insertion loss of 0.3-0.4 dB. The isolation of this initial prototype is at least 28 dB in the same band, and it can be increased by improving the short circuit elements.