Wide-Angle Beam-Scanning Algorithm for Low Sidelobe Level and Low Axial Ratio Applied to Circularly Polarized Phased Array

A wide-angle beam-scanning algorithm to suppress the sidelobe and enhance axial ratio (AR) is proposed for circularly polarized (CP) phased arrays. The deterioration of sidelobe and AR in wide-angle beam scanning is investigated in this paper. To address the drawbacks, an improved wide-angle beam-scanning algorithm with phase-only particle swarm optimization (PSO) pattern optimization is presented. Both the sidelobe level and AR are considered in the fitness function, ensuring a low sidelobe level and favorable AR in the 3-dB beamwidth. Besides, mutual coupling between the elements is taken into consideration to optimize wide-angle beams precisely. The algorithm is simulated and validated using a $4 \times 4 \text{CP}$ antenna array. It is demonstrated that a scanning range of ± 40° is achieved. The sidelobe level is over 9 dB, and AR is lower than 2.3 dB in the 3-dB beamwidth.