A Novel Design Method for Wide-Angle Beam-Scanning Phased Arrays Using Near-Field Coupling Effect and Port Self-Decoupling Techniques

In this article, a novel design method for wide-angle beam-scanning phased arrays is investigated. Different from the traditional method that focuses on widebeam antenna element, this novel method aims to directly obtain widebeam active element pattern (AEP) by skillfully using the near-field coupling effect between elements. Meanwhile, the port self-decoupling technique is introduced in phased arrays to obtain high port isolation. As a result, without adding any beam-broadening structure and decoupling structure, the phased array, featuring extremely simple structure and excellent beam-scanning performance, can be constructed by a typical narrow-beam antenna element. As examples, two millimeter-wave (mm-wave) eight-element linear phased arrays are designed based on a microstrip patch antenna (MPA) and a dielectric resonator antenna (DRA), respectively. Although the half-power beamwidths (HPBWs) of the two antenna elements are only 96 degrees and 94 degrees, the beam-scanning ranges of their corresponding phased arrays reach +/- 63 degrees and +/- 61 degrees, respectively. For verification, a prototype of the proposed mm-wave MPA phased array is fabricated and measured. The results show that this phased array can scan from -64 degrees to +64 degrees with a very low gain fluctuation of 1.0 dB (varying between 13.5 and 14.5 dBi), and the peak sidelobe level (SLL) is less than -8.3 dB over the wide scanning range.