Wideband beamforming using fan filter

A novel approach to wideband beamforming using FIR (finite impulse response) fan filters is presented. The method is based on two-dimensional filtering for the outputs of a linear array of sensors. To beamform in the broadside of the array, a symmetrical 90°/n filter is employed. The filter in which the angle of fan is more acute can form the narrower beam over the full band while the order of the filter becomes higher. To beamform in the direction along the array, an asymmetrical 45° fan filter is used. As aliasing occurs in this beamforming, the band which is available is limited a little in width. A general implementation of the FIR fan filter beamformer is given as the parallel connection of one-dimensional FIR filters