A compact phase-shifting unit for phased array antennas

A compact reconfigurable defected microstrip structure (RDMS) unit is proposed for phase shifters used in phased array antennas. The RDMS unit can introduce a phase shift when working in two different states. The performance of the RDMS unit, including the phase shift and insertion loss, is found to have closely correlations with some key dimensions, which is elucidated using equations and simulations. A RDMS unit with optimized dimensions is fabricated as an example, and measured to have a phase shift of 20° at 5.2 GHz. Then, two of such RDMS units are cascaded, resulting in a 1-bit phase shifter which has a doubled phase shift but smaller insertion loss. The proposed phase shifter is compact, low cost, and easy to be fabricated and integrated in microstrip systems. Therefore, it offers a low-cost and low-profile solution to phase shifts in phased array antennas.