PURPOSE: To prevent the reduction of the gain even in the case of a large angle formed between the main beam direction and a perpendicular line stood on the antenna array face by weighting the amplitude balance of an array antenna and suppressing the grating lobe or/and the side lobe at the time of beam scanning.

CONSTITUTION: Phase shifters 1, 2,...n are added to antenna elements A1, A2,...An respectively, and a controller CONT controls phase shifters, and a distributor CDIV weights the amplitude value of the signal to be supplied to each antenna and weights amplitude values of incoming signals from antennas to the distributor and synthesizes them and outputs the synthesis result to a transmitter-receiver TRX. Binomial distribution or Tchebycheff's weighting is proper as the weighting method. When the exciting current supplied to each antenna element or the phased array antenna is weighted, the gain is less reduced in comparison with the main beam in the front of the antenna array face even if the main beam is large deviated.