Exploring Adaptive Beamformers with the Null Placing Sidelobe Suppression Algorithm

This work explores sidelobe suppression to adaptive beamformers (ABF) based on a recently introduced technique for null placement, proposing new approaches that employ constrained adaptive algorithms. ABF methods primarily aim at a distortionless response with interference suppression, usually not oriented to sidelobe level (SLL) control. However, SLL control might be crucial for radiation efficiency optimization and signal-to-interference-plus-noise ratio enhancement. Therefore, the purpose is to control SLL concomitantly with reducing the interference of undesired signals impinging on the array. The signal reception is based herein on a complex baseband snapshot vector model, passing through a typical receiver architecture. After a comprehensive overview of the signal model, the text delves into linearly constrained adaptive filters, setting the groundwork for detailing how to apply the null placement sidelobe suppression technique (NP-SLS) to constrained versions of adaptive filtering algorithms. The main idea behind the NP-SLS algorithm is the addition of linear constraints to place nulls on the sidelobe peaks above a specified minimum level. Simulation results demonstrate the effectiveness of the proposed approach in controlling SLL and its effect on adaptive interference suppression for different numbers of antennas. The study summarizes the findings, which may help future research in adaptive beamforming with enhanced sidelobe control.