Robust near field broadband beamforming in the presence of steering vector mismatches

Adaptive beamformers suffer from severe performance degradation in the presence of steering vector mismatches due to the location errors and other array imperfections. This degradation is more severe in the near field due to the difficulty in estimating near field signal locations especially the radial distances. This paper presents two robust beamforming algorithms based on diagonal loading approach which is one of the most widely used and effective method to improve robustness of adaptive beamformers. The proposed algorithms do not use pre-steered arrays and are computationally efficient. The techniques presented in this paper extend the idea of previously published paper for far field beamforming to near field broadband beamforming. Examples show the enhanced performance of robustness and capability of distance discrimination of the proposed broadband beamformers.