Minimizing peak sidelobe level and maximizing array efficiency in array antenna using phase-only beamforming based on modified GA-SQP algorithm

Phase-only beamforming offers a hardware-efficient alternative to amplitude tapering, but achieving low sidelobe levels while maintaining high array efficiency remains challenging. This paper proposes a novel two-objective optimization algorithm for phase-only beamforming. The proposed method combines Genetic Algorithm with Sequential Quadratic Programming to enhance the performance. This approach utilizes a multi-objective optimization framework to minimize peak sidelobe level (PSLL) while simultaneously maximizing array efficiency. The proposed method performs better than the existing phase-only beamforming methods in terms of both PSLL and array efficiency. Computer simulation results are presented for the PSLL and array efficiency of linear arrays with 20, 32, 40, 55, 60, 80, and 100 elements to validate these findings, with results compared to other phase-only methods. Furthermore, it is shown that the proposed method exhibits enhanced performance compared to well-known amplitude tapering windows in managing the trade-off between peak sidelobe level, beamwidth, and array efficiency. For two-dimensional planar arrays, the proposed method demonstrates improved performance compared to the existing phase-only beamforming methods in both peak sidelobe level and array efficiency criteria. A comparison has been performed for circular planar arrays with 32 and 172 elements, demonstrating that the proposed method achieves an improvement of 8.8% to 21.8% in array efficiency while simultaneously improving the PSLL by approximately 1.5 dB. For square 15 by 15 planar arrays, a considerable PSLL enhancement of at least 6.8 dB is obtained compared to the existing phase-only approach while achieving narrower beamwidth.