Frequency-independent beamforming

The beamwidth of a linear array decreases as frequency increases. For broadband beamformers such as microphone arrays for teleconferencing, this frequency dependence implies that signals incident on the outer portions of the main beam are subject to an undesirable lowpass filtering process. In the paper several ways of attaining beamwidth constancy are discussed, including a novel method based on superimposing several marginally steered beams to form a constant beamwidth multi-beam. This method provides an analytically tractable framework for designing realizable constant beamwidth beamformers