Estimation of beam forming accuracy for satellite experiment toward SPS

Nowadays, Solar Power Station is expected to solve energy problems. Therefore an experiment to demonstrate wireless energy transfer technology is planned in Japan. In the experiment, a satellite in low orbit of 370 km in space transfers energy to receiving antennas on the Earth by microwave of 5.8 GHz. In this demonstration, it is necessary to control the beam direction within 0.2°. In order to prove that it is feasible, practical experiments were conducted by using Advanced Phased Array System for Microwave Power Transmission, where the distance between the transmitting and receiving antenna is 6.5 meters. We changed control bits of phase shifter number from 1bit to 5bits and the number of sub array antenna. In each case, we measured the beam direction errors. In the experiments, we changed the beam direction from -30° to 30°. As a result, we conclude that we can control the beam direction with an accuracy of 0.2° or less.