PURPOSE: To suppress the deterioration of a desired wave component by providing a discrimination circuit to an output terminal of a weight circuit and outputting a preset value as a weighting value in case of the amplitude of an obtained complex number weight value not satisfying the set value.

CONSTITUTION: When only a desired wave is made incident in the direction of a mian lobe of a main antenna, each output of the main antenna and an auxiliary antenna is inputted to a weighting circuit 12, from which a weight value is obtained while the output voltage of the main antenna is cancelled. In this case, the amplitude of the weight value in complex number is nearly equal to the ratio of the voltage output resulting from the wave incoming from the main lobe direction to that of the auxiliary antenna and the gain of the auxiliary antenna is nearly equal to the gain at the maximum side lobe of the main antenna, then the amplitude of the weight value is a very large value. Thus, a discrimination circuit 11 compares said amplitude with a condition value, and if the amplitude exceeds it, the condition value is outputted as the weight value in place of the weight obtained by the circuit 12.