Novel phase reconfigurable synthesized transmission line and its application to reconfigurable hybrid coupler

A novel phase reconfigurable synthesized transmission line is proposed in this paper. By utilizing quasi-lumped elements and varactor diodes, the synthesized line functions as a 1-bit phase shifter by switching its electrical length between two states; the characteristic impedance, meanwhile, is kept unaltered. The design concept, circuit model, and performance are carefully investigated and discussed. Based on newly developed synthesized line, a reconfigurable hybrid coupler, which can be electrically switched between a rat-race or branch-line coupler at the same frequency, is designed as a demonstration. The measured results showed acceptable insertion loss level and good output phase response.