• M Omiya
• Kiyohito Itoh

SPS2000 is a strawman model of solar power satellites (SPS) (1) with microwave power output of 10 MW, which was proposed by the SPS working group of the Institute of Space and Astronautical Science (ISAS) (2, 3). The primary objective of SPS2000 research is to show whether SPS could be realized with the present technology and to find out technical problems. The conceptual study of SPS2000 is now being carried out under the assumption that the first construction will be started before the beginning of the twenty first century. SPS2000 transforms the DC power generated by huge solar arrays to microwave power at 2.45 GHz and transmits it to the rectennas on the earth while it moves from west to east in an equatorial low earth orbit (LEO) of 1100 km altitude. Transmission is possible when the rectenna can be in the field of view of the controllable microwave beam from SPS2000. Therefore, SPS2000 should always detect the location of the rectenna and direct a microwave beam toward the rectenna. In order to perform the beam scan, the spacetenna should have a function of a phased-array antenna (4, 5). We discuss a configuration of spacetenna of SPS2000 and an electrical design of its feeding network for power transmission antenna elements. Furthermore, we describe the conceptual design of SPS2000 followed by the configuration of the spacetenna and the feeding network. On the basis of the spacetenna proposed above, we design a functional system model of SPS2000 as a demonstration model and construct microwave circuits employing silicon (Si) semiconductors since there are many advantages in Si technology compared with others in terms of cost reduction, robustness of the system and extraterrestrial resources.