Multirate Method for Constant Beamwidth Beamforming of Nested Array

A multirate method with general parameter filter banks for beamforming with constant beamwidth based on harmonic nested array is proposed. The harmonic nested array is composed of several uniformly-spaced linear subarrays, each of which processes an octave subband signal respectively. These nonuniform subband signals are implemented by general parameter filter banks. Each subarray beamforming is carried out by space-frequency signal processing approach, and the number of weights of each subarray is determined by the total frequency bandwidth of its entire subbands correspondingly. This processing architecture based beamformer splits the wideband signal into several narrow subband ones which are processed in parallel, and each subarray is operating with the lowest rate, which contributes to decreasing the computational load significantly and improving the speed and performances as well. Simulations show that the proposed beamformer is competent for constant beamwidth beamforming with much lower computation complexity.