Robust beampattern control for steerable frequency-invariant beamforming in the presence of sensor imperfections

Abstract

Wideband beamformers are known sensitive to sensor imperfections, especially for small-sized sensor arrays. Mean performance optimization (MPO) is a commonly used criterion for the design of robust wideband beamformers in the presence of sensor imperfections, which aims to synthesize the mean beampattern. However, the existing designs for robust wideband beamformers cannot guarantee precise control of the mean beampattern. In this paper, we propose a MPO-criterion-based robust design approach for steerable wideband beamformers (SWBs) using a weighted spatial response variation (SRV) measure. By exploiting the increased degrees of freedom provided by the weighted-SRV, the proposed robust SWB design can achieve a frequency-invariant mean beampattern with both mainlobe inconsistency and sidelobe level being able to be precisely controlled. We develop a theory and the corresponding algorithm to find the solution for the weighting function of the weighted-SRV-based cost function to achieve precise mean beampattern control. Some insights into the effect of sensor imperfections on the achievable frequency invariance are also revealed. The effectiveness of the proposed design is verified by the simulation results.