A phased-array architecture for retrodirective microwave power transmission from the space solar power satellite

This paper presents a phased array architecture for retrodirective microwave wireless power transmission from the space solar power satellite (SPS). The proposed architecture uses a 2.9-GHz pilot beam and a 5.8-GHz transmit beam, with retrodirective phasing implemented directly at RF. Experimental and theoretical results are given to validate the approach.

I Retrodirective Capability for the SPS System

The SPS concept envisions a satellite placed in geosynchronous orbit for collecting and converting solar power to electrical power The SPS satellite continuously transmits the electrical power it generates down to the earth using a microwave beam On the earth's surface, the microwave beam can be received and converted back to electrical power on the gigawatt scale using a rectifying antenna array or “rectenna” array. To ensure maximum operating efficiency and to eliminate environmental concerns, the microwave transmission system uses retrodirective control That is, a pilot beam signal transmitted from the phase center of the rectenna site to the orbiting satellite ensures that the high-power microwave beam always points on-target The SPS system would make solar power available for baseline. electrical power during 99% of the year and operate with a de-to-de conversion efficiency greater than 45% [1], [2].