Millimeter-Wave Beam-Scanning Phased Array With Switchable Broadside and Endfire Radiation Pattern Using Phase-Controlled Elements

To improve the millimeter-wave signal coverage, this article presents a beam-scanning millimeter-wave phased array with switchable broadside and endfire radiation patterns. The proposed array is made up of four phase-controlled antenna elements, which are linearly arranged. Each antenna element comprises two symmetrical rectangular stacked patches and a linearly tapered slot, which are fed by an “n”-shaped microstrip feeding line with two ports. When the port-to-port phase difference is 0, the antenna works in common mode. The stacked patches are excited, realizing broadside radiation pattern. The antenna is switched to differential mode with a phase difference of 180°. The tapered slot is excited, achieving endfire radiation pattern. In this way, the millimeter-wave phased array has switchable radiation pattern and a beam-scanning angle of ±55° and ±65° in the broadside and endfire directions, respectively. Compared with the previous works, the proposed array has a wider operating bandwidth of 24–28 GHz with competitively large scanning angle and high gain. The proposed array does not require any active component, so has low loss and structural complexity.