A Novel Resonant Microstrip RF Phase Shifter using Defected Ground Structure

In this paper, novel RF phase shifter structure using DGS (Defected Ground Structure) is proposed for the low insertion loss and linear phase variation characteristic. Equivalent circuit of the proposed phase shifter is derived by employing the equivalent circuit of DGS section. Varactor diode is chosen as an electrical control device, which is placed on metallic backside ground plane. Theoretical consideration and experiments verify the presented phase shifter. The experimental results for a single-stage resonant phase shifter show a range of 25°-phase variation with 0.5dB insertion loss within an operating bandwidth of 10%, when the center frequency is 900MHz.