Analysis of a broadband beamformer based on trapezoidal filters and nested arrays

A broadband beamformer using nested arrays, multi-rate techniques and multi-dimensional filters, recently proposed in [11-12], will be analyzed in detail. Using appropriate subsampling in space and time for each nested subarray leads to signals with the same region of support (ROS) in the 2D frequency domain for all subarrays. This ROS will be shown to be the top octave of the signal bandwidth and can be used to obtain higher selectivity at low frequencies. An example of the beampattern obtained using the proposed approach illustrates the almost frequency-invariant response of the beamformer.