A Compact Microstrip Phase Shifter Employing Reconfigurable Defected Microstrip Structure (RDMS) for Phased Array Antennas

A compact phase shifter using reconfigurable defected microstrip structure (RDMS) is proposed for phased array antennas. A complete phase shifter design scheme that serves as an engineering guidance is described. Stepwise phase shifters that have phase-shifting ranges of 90° and 180° with a step size of 45° are designed, fabricated, and tested. The experimental results demonstrate that the size, maximum insertion loss of the phase shifters, and the quantity of the lumped elements are reduced by 80%-90%, 25%-30%, and 50%, respectively, compared to our previous work. Subsequently, a four-element phased array is built employing such RDMS-based phase shifters, realizing a size reduction of 55% in the array size. The measurement results show that the phased array antenna is able to switch its main beam between -15°, 0°, and 15° in the H-plane, with the average realized gain around 10 dBi.