Abstract: During the beamforming process, the main lobe directivity of the array antenna pattern is affected by the number of array elements. The fewer the number of array elements, the wider the beam width, and the smaller the effective scanning range of the array. However, increasing the array elements will increase the cost and complexity of the system. To address this problem, a beamforming method that enhances main lobe directivity is proposed and integrated into the Null Steering Beamformer (NSB) algorithm. Without adding array elements, NSB will generate an accurate zero point by setting up virtual interference points around the main lobe. Due to the distance repulsion between the main lobe and the zero point, the main lobe will shift slightly toward the target direction, thereby weakening the degree of the main lobe shift. Numerical experiments show that compared with the conventional NSB algorithm, this method effectively reduces the main lobe offset. Finally, the method proposed in this article is combined with the Linear Constrained Minimum Variance (LCMV) algorithm, demonstrating good main lobe directionality.

Key words: Beamforming, Main lobe offset, Virtual interference point, Null String Beamforming algorithm