Wide-Angle Beam-Scanning Millimeter-Wave Antenna Array Using Phase-Controlled Beam-Steerable Elements

A millimeter-wave beam-steerable antenna by controlling the phase difference between the feeding ports is proposed and applied to achieve a wide-angle beam-scanning millimeter-wave phased array. The antenna element consists of a square patch and a square microstrip loop, which are fed by two separate ports. Importantly, neither any active component in the millimeter-wave frequency band nor any dc biasing circuit is needed in the proposed beam-steerable antenna. The radiation patterns of the loop element in TM22 mode and the patch element in TM10 mode are synthesized with different phases. The radiation beam of the antenna can be switched by only controlling the phase difference between these two ports. Furthermore, by using the proposed beam-steerable antenna element, the element and array factors of the millimeter-wave phased array can be tuned simultaneously. Therefore, a wide scanning angle of the phased array is realized in the E-plane. The proposed millimeter-wave phased array features a compact and simple structure without using active components and can avoid the loss caused by millimeter-wave lumped components. The results indicate a beam-scanning range of ±76° within the frequency band of 26–30 GHz.