Side Lobe Control Method in Subarray Beamforming Based on Randomly Staggered Combination Array

In order to reduce the difficulty of engineering implementation of the underwater large-scale sonar array beamforming algorithm, a large planar array with element-level partitioned beam scanning mode can be adopted, without changing the weight of amplitude and phase of the array element in each scanning partition, and only the subarray-level digital beamforming is adopted, then the beam scanning of the array can be completed. However, this mode will bring high side lobe problems. To solve this problem, a new method of randomly staggered combination array based on regular subarray division is proposed, which breaks the limit of the existing research method that the offset is an integer multiple of the element spacing, and uses genetic algorithm to simultaneously optimize the offset of adjacent columns of the subarray and the subarray-level weight coefficients. The main side lobe ratio is used as the fitness function. Hence, the highest side lobe of the integrated pattern is the lowest and the grating lobe effect caused by the large element spacing at the subarray level is reduced. The simulation results show that the use of random staggered subarray structure, the optimized formation and weight coefficients can effectively avoid the high side lobe in large partitions and obtain a higher main side lobe ratio in different partitions. The control effect of the side lobes is better than that of the existing staggered combination array method, which verifies the effectiveness of the proposed method.