Frequency Invariant Beamformers for Underwater Sound

The increasingly widespread use of broadband acoustic signals for underwater communications, sonars for survey work and fisheries research incentivises the design of beamformers with frequency-invariant beampatterns to minimise angular variations of the signal spectral content and angular width of the beam with frequency. In this paper, we present a technique for frequency invariant beam generation using a delay and sum procedures for linear and 2D arrays with half-wavelength element spacing at the highest frequency of interest and a transformation of this approach into a 3D array topology.