AVS array with spatial sampling above the Nyquist criterion for beamforming applications

In recent times MEMS transducers that are capable of measuring particle velocity have been developed. By integrating multiple particle velocity transducers with a pressure transducer, an Acoustic Vector Sensor (AVS) can be realized. The application of AVSs in an array configuration have been shown to have distinct advantages in comparison to the equivalent Acoustic Pressure Sensor (APS) arrays, as they make use of both interference between them and intrinsic directional information of each of the particle velocity sensors. Moreover the matched filter based beam-pattern of an AVS array can be expressed as the product of an equivalent APS array beam-pattern and an additional frequency independent term which is referred to as Velocity Gain Modulation (VGM) term. In this paper it is shown that due to the presence of the VGM term the effects of spatial-aliasing is reduced as the AVS array is spatially sampled above the Nyquist criteria. Resulting in the larger effective aperture of an AVS array, hence the resolution and design bandwidth is increased as well. Also we evaluate the performance in terms of side lobe level reduction and main lobe width of such an AVS array, in particular for a Uniform Linear Array and a Uniform Rectangular Array, based on its beam-patterns. Furthermore, the experimental results are presented to comprehend the theoretical results.