Robust and efficient broadband beamforming algorithms in the presence of steering angle mismatch using variable loading

Steering angle errors are known to be a major cause of performance degradation of adaptive beamformers, especially when the signal of interest is present in the measurements. Diagonal loading is one of the most widely used and effective methods to improve robustness of adaptive beamformers. This paper presents two robust beamforming algorithms using efficient realisation techniques. The techniques do not use a pre-steered array and allow an array designer to specify the frequency response of the processor in the look direction and steered the main beam of specified frequency response in an arbitrary direction. The proposed techniques are computationally efficient. The techniques used in the paper extend two previously published techniques used for narrow band beamforming to broadband beamforming. Simulation results exhibit enhanced robustness performance of the broadband beamformer.