Study on High-efficiency and Low-noise Wireless Power Transmission for Solar Power Station / Satellite

A Solar Power Station/Satellite (SPS) is expected to become one of the sustainable energy sources for the next generation. One of the most important technologies for realization of the SPS is Wireless Power Transmission (WPT) from space to the Earth. The objective of the present study is to develop high-efficiency and low-noise WPT. A SPS requires high overall WPT efficiency, and a high-efficiency WPT system also contributes to cost reduction and lightness in weight of the SPS from the viewpoint of thermal management. Low-noise WPT is also important since a SPS is necessary to ensure electromagnetic compatibility (EMC) with other radio applications. In our research group, a magnetron is used for a microwave power source of a SPS transmitting system, because its DC-RF conversion efficiency is higher, it costs less, and it has smaller weight/power ratio than solid state devices. However, a magnetron has a wide oscillation bandwidth and it generates spurious noises in various frequency bands. We have achieved magnetron noise reduction, developed a Phase-Controlled Magnetron (PCM), phased array transmitting systems (SPORTS systems) and a compact 5.8GHz PCM (COMET). A development of 5.8GHz CW magnetrons also contributes to reduction in size and weight of the SPS transmitting system, compared to the conventional 2.45GHz magnetron. In this paper, our recent research activities on the WPT transmitting systems are introduced.