A beamformer includes a number (T) of consecutive combining stages. A Tth combining stage includes a converging unit. Each of first to (T−1)th combining stages includes a plurality of converging units. The number of the converging units in a preceding combining stage is greater than that of a succeeding combining stage. Each converging unit in the first combining stage combines three arrival signals from an antenna array in accordance with corresponding weights so as to form an output signal. Each converging unit in each of second to (T−1)th combining stages combines output signals of three corresponding converging units in an immediately preceding combining stage in accordance with corresponding weights so as to form an output signal. The converging unit of the Tth combining stage combines the output signals from the converging units in the (T−1)th combining stage in accordance with corresponding weights so as to form an output signal that serves as an array pattern.