Broadband beamforming using elementary shape invariant beampatterns

This paper presents a new method of designing a beamformer having a desired broadband beampattern with focusing capability to operate at any radial distance from the array origin. An important consequence of our result is that the beamformer processing can be factored in to three levels of filtering: (i) beampattern independent elementary beamformers; (ii) beampattern shape dependent filters; and (iii) radial zooming filters where a single parameter can be adjusted to zoom-focus the array to a desired radial distance from the array origin. As an illustration the method is applied to the problem of producing a practical array design that achieves a frequency invariant beampattern over the frequency range of 1:10.