Axial Ratio Improvement for Wide-Angle Scanning Circularly-Polarized Phased Array of Circular Patch Antennas

抄録

This study presents a novel technique to improve axial ratio (AR) of wide-angle scanning phased array. This technique can be applied to phased arrays of reconfigurable dual-polarized circular patch antennas: each antenna element has two feeding channels, with separate variable gain amplifier and phase shifter for each channel. In the proposed technique, compensation weights, excitation amplitudes and phases of each feeding channels, for the AR compensation are controlled based on a closed-form design formula. The design formula is obtained by approximately formulating an active element pattern of the circular patch antenna array. Calculation conditions for the design formula and the effectiveness of the proposed technique have been evaluated by the simulation of a 41-element array. In the simulation, the worst AR in the designated coverage range of ±70^° was improved from 5.8 dB to 2.0 dB by the proposed technique. We experimentally tested the proposed technique using a 1024-element phased array. The measured AR was improved from 5.8 dB to 1.9 dB at 70^° scan by the proposed technique.