Frequency-independent beamformer with low response error

A method is developed for designing broadband beamformers with highly frequency-invariant behavior. The method combines harmonic nesting with filter-and-sum beamforming, yielding systems with efficient log-periodic transducer structures and plane wave responses which deviate from the desired response by less than 1% of the peak mainlobe response. In particular, null locations are very constant with frequency, allowing the nulling of directional broadband interference. A digital implementation covering audio frequencies (500-7200 Hz) is built and demonstrates results in good agreement with simulations, yielding deviations under 5% of peak response