On the design of digital broadband beamformer for uniform circular array with frequency invariant characteristics

The design of a digital uniform circular array frequency invariant beamformer (UCA-FIB) is proposed. After transformation and removal of the frequency dependency of the individual phase modes, the frequency invariant phase modes are linearly combined with the spatial filter coefficients to form the far field pattern of the array. As a result, such a beamformer is a wideband frequency invariant beamformer. For simultaneous beamforming, we propose a UCA-FIB DFT filterbank for concurrent beamforming in different directions. Design examples demonstrate that the proposed UCA-FIB can form deep s and sharp peaks with good frequency invariant characteristics, while the UCA-FIB DFT can efficiently divide the array neighboring area into small sectors spatially.