A Novel Method to Design Steerable Differential Beamformer Using Linear Acoustics Vector Sensor Array
Feng Chen, Ke Ma, Yapeng Mao, Desen Yang, Yi Zhang, Jie Shi, Shiqi Mo, Chenyang Gui, Song Li
Abstract
Differential beamforming techniques have gained significant attention due to their frequency-independent beampatterns, applicability for small apertures, and super-directivity. It is commonly known that the main lobe of a beam pattern based on a linear array is typically aligned with the end-fire direction. However, in some application scenarios, aligning the main lobe in the end-fire direction may not meet the actual requirements. This article focuses on studying the steering problem of differential beamformers based on linear acoustics vector sensor arrays (LAVSs). We propose a steerable differential beamformer for LAVSs, which addresses the problem of non-steerable beam patterns of linear arrays. Our approach involves approximating the beam pattern using a series expansion of the weighted steering vector to achieve frequency-independent differential directivity. The major contributions of this article include, but are not limited to, the following: First, we derive the first-order to third-order differential directivity based on the acoustics vector sensor (AVS) signal model, and obtain the weights of the corresponding channels using the least squares method. Second, we provide a theoretical analysis of the steering differential beamformer, demonstrating that the maximum directivity factor (DF) is a function of the steering angle. Finally, we conduct simulation experiments to validate the proposed method.