Sharp (Stationary High Altitude Relay Platform). Part a: Technical Feasibility of Microwave-Powered Airplanes

摘要

Various types of airplanes and power transmission systems were analyzed. It was found that the cost of a powering system would be considerably reduced if it were to be operated at an ISM frequency of 5.8 GHz rather than at 2.45 GHz. A currently available 2.45 GHz rectenna, capable of power conversion at a power flux density of 500W/square meters was tested to determine microwave to dc conversion efficiency and levels of out-of-band spurious emissions. To gain experience with microwave powering of airplanes, a 1.3m wing span model airplane has been designed and fitted with a novel type of dual polarization rectenna. It is planned to fly this airplane on microwave power. A 6kW transmitter and a 4.5m tracking antenna will be used to provide the power flux density required to fly the airplane to altitudes of up to 70m. It is concluded that there are no insuperable technical problems to achieving feasibility of the airplane and power transmission system. However, an acceptable rectenna has not yet been identified. Further, there are uncertainties in performance of lightweight airplanes in the operational environment.