Elements in an ultrasound array are activated according to a transmit beamformer to create a series of transmit beams. For each transmit beam, the first stage of a receive beamformer determines a plurality of primary receive beams. A second beamformer stage then computes secondary receive beams as a function of the primary receive beams that correspond to return signals from different transmit beams to a common receive beam origin. For example, each secondary receive beam may be calculated as a function of the weighted, time-delayed sum of the primary receive beams. At least one of the secondary receive beams is then output from the beamformer to be used in creating a displayed image.
