Microwave Power Beaming

Microwave power beaming is the transmission of electrical energy using microwave-frequency electromagnetic radiation, typically in the 2.45 GHz or 5.8 GHz industrial, scientific, and medical (ISM) bands. In SBSP designs, microwave beaming converts DC electrical power aboard an orbital platform into a directed microwave beam using a large phased array transmitting antenna, propagates that beam through the atmosphere, and receives it at a ground station equipped with a rectenna array. Microwave frequencies were selected in early SBSP designs because they pass through clouds and rain with relatively low attenuation and can achieve beam-forming at the large apertures required for orbital distances. The main constraints include the large aperture sizes required for both transmitting and receiving arrays, regulatory coordination for frequency use, safety exclusion zones around the receiving beam, and pointing accuracy requirements from geostationary altitude.