Broadband Circularly Polarized Beam-Steering Antenna Array

A wideband circular polarized (CP) switched-beam patch antenna array is presented in this communication. The switched-beam system consists of four two-section branch-line couplers, two wideband 45 phase shifters and 1 × 4 proximity-coupled L-probe feeding CP microstrip patch antenna array. With such an arrangement, the proposed array can obtain a wide axial ratio (AR) bandwidth than that of conventional switched-beam CP antenna array. Measured results showed this array has an impedance bandwidth over a frequency range of 4.04-5.78 GHz (~36%) for |S₁₁| <; -10 dB and AR bandwidth from 4.3 to 5.75 GHz (~29%) for AR <; 3dB when the main beam of array is scanned to different four directions.