The present invention is provided with: a plurality of antenna units each including a plurality of antenna elements and a partial synthesizer that synthesizes first output signals of the respective antenna elements and outputs a second output signal; a partial power detection means that measures signal intensities of the respective second output signals; a position determination unit that determines the position of a communication device serving as a communication target based on the measured signal intensities of the respective second output signals; a summing synthesizer that synthesizes the second output signals of the plurality of antenna units and outputs a third output signal; and a phase control unit that controls phases of the respective antenna elements such that a main lobe, which is a beam having a maximum signal intensity for the third output signal, is directed to the position of the communication device determined by the position determination unit.