Design of Frequency Invariant Beamformer for Broadband Arrays

A simple method for the design of a class of arrays with frequency invariant beam patterns is proposed. Starting from the desired frequency invariant beam pattern of an n-D array, the proposed method uses a series of substitutions and an n-D inverse Fourier transform to obtain the desired frequency responses of the filters following each sensor. Given their desired frequency responses, these filters can be realized by either an analogue filter or a digital filter. Hence the proposed method can cover the design of broadband arrays with either analogue signals or discrete signals. Two design examples are provided, with one for a linear array and one for a planar array.