PURPOSE: To realize the inprovement of radiation-power efficiency, prevention of interference disturbance, and simplification of the antenna constitution of a master station, by attaining information interchanges with a plural number of subordinate stations in a time-division mode by scanning the direction of the directional antenna of the master station within a fixed range.

CONSTITUTION: This system is provided with master station 100 equipped with directional antenna 110 whose beam direction is scanned and controlled over a fixed range, subordinate stations 200A and 200B which are arranged confronting to the master station and make information interchanges, and transmitter-receivers 120 and 220 which make the information transfer between the master station and a subordinate station to which the beam direction of directional antenna 110 confronts, so that an information interchange between the master station and subordinate station will be done in a time-division mode through the scanning of the antenna beam