Design of Frequency-Invariant Beamformers Using a Weighted Spatial-Response-Variance Measure

The spatial-response-variance (SRV) is a widely used measure in the design of frequency-invariant (FI) beamformers. Compared with the conventional design approaches for FI-beamformers, there is no need to pre-specify a fixed desired beampattern in the SRV-based design counterparts. Therefore, the SRV-based design approaches enjoy more degrees of freedom (DOFs) than the conventional ones, which contributes to their higher performance in the FI-beamformer design. In this paper, we introduce a weighted SRV measure, which is a generalized version of the SRV, and then propose a weighted-SRV-based FI-beamformer design approach by exploiting the DOFs offered by the weighting coefficients of the weighted SRV. It shows that the FI performance of the resultant beamformers can be further improved compared with the existing SRV-based design. Particularly, array response can be precisely controlled, including mainlobe ripple, sidelobe level and notch depth. Moreover, the weighted-SRV-based design can operate over a wider frequency range, while the SRV-based counterpart may fail.