Microwave wireless-power transmission to high-altitude-platform systems

摘要

High-altitude-platform (HAP) systems belong to a new technology that has the potential to become a low-cost and useful alternative or complement to geostationary-Earth-orbit (GEO) and low-Earth-orbit (LEO) radio-relay satellites. The HAP concepts, developments, and applications are also the subject of two special sections in the Radio Science Bulletin(March 2010 and September 2010 issues, Nos. 332 and 334), and this paper is included in the second such section. However, the problems of the long sun eclipses and stabilization control of HAPs require significant electrical power and energy, which may delay the realization of long-operation stratospheric HAPs. A possible solution could be the utilization of wireless-power-transmission (WPT) terrestrial systems feeding HAPs. This paper starts with an introduction that defines HAPs, wireless-power transmission, and solar-power satellite (SPS) systems. The concepts of the different wireless-power-transmission systems is followed by a review of the genesis and development of wireless-power-transmission systems. However, the main subject of this paper concentrates on microwave (MW) wireless-power-transmission systems for feeding stratospheric HAP airships. A thorough description of future projects in microwave wireless-power-transmission systems from terrestrial bases to HAPs is therefore presented. In this description, we utilize several research and development results obtained in the evaluation steps of the fascinating solar-power-satellite projects, especially by Japanese and USA scientists and engineers. The solar-power-satellite evaluation results are thus very useful for the future design and implementation of microwave wireless-power-transmission systems, making HAPs much easier to realize. Comparisons between microwave wireless-power-transmission systems for terrestrial links, for stratospheric HAPs, and from solar-power satellites in a geosynchronous orbit are provided. In the Appendix, simple methods for computing the areas of the microwave wireless-power-transmission transmitting-antenna arrays, microwave beams, and rectenna as functions of the required power-transmission efficiency, separation distances, and frequency bands are developed. The results show that the required areas and weights of the microwave wireless-power-transmission systems are significantly less for HAPs than for solar-power satellites. However, the design and realization of microwave wireless-power-transmission systems for HAPs could also be useful for the realization and preliminary tests of solar-power-satellite systems.