A novel reflection-type phase shifter employing defected ground structure

A new microstrip reflection-type phase shifter based on branch-line directional coupler has been presented. It has a lot of distinct features including compact structure, high range of phase modulation, constant insertion loss and so forth. These characteristics are obtained by adding appropriate varactor to the reflection terminal and employing open stub unit with defected ground structure (DGS). The implemented phase shifter achieves measured maximal relative phase shift of 220°, averaged insertion loss of 4.6 dB and return loss better than 26 dB at 2 GHz. The measurement results and simulation results show good agreement.