Abstract: In order to control the direction of a beam antenna, at least one magnetic sensor is attached to the antenna for measuring at least one of the horizontal and vertical components of the geomagnetic field. A magnetic sensor circuit converts the output of the magnetic sensor into an electric signal which varies corresponding to changes in the measured geomagnetic field according to the direction of the antenna. A processor determines the current direction of the antenna based on an output of the magnetic sensor circuit and outputs a control signal for setting the antenna in a desired direction. A motor rotates the antenna, and a power source drives the motor. A control unit receptive of a motor control signal output by the processor controls the rotation of the antenna.