A Defected Microstrip Structure (DMS)-Based Phase Shifter and Its Application to Beamforming Antennas

In this paper, a beam-steering antenna array that employs a new type of reconfigurable phase shifter is presented. The phase shifter consists of a number of cascaded reconfigurable defected microstrip structure (DMS) units. Each DMS unit is made by etching a slot in a microstrip line and loading the slot with PIN diodes. The “on” and “off” states of the PIN diodes in the DMS unit provide the phase shifts by changing the current paths. Analyses on the performance of various phase shifters cascading different numbers of DMS units are conducted by both simulations and experiments. Using the proposed phase-shifter units and Wilkinson power dividers, a four-element beam-steering antenna array was designed, fabricated, and tested. Experimental results agree well with the simulated ones. The proposed antenna array employing DMS-based phase shifters offers a low-cost solution to beamforming in wireless communications.