著者

Dickinson Richard M.

出版者

一般社団法人電子情報通信学会

雑誌

電子情報通信学会技術研究報告. SANE, 宇宙・航行エレクトロニクス

巻号頁・発行日

vol.97, no.55, 1997-05-22

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The cost optimized point-design of a 2.45 GHz microwave beam powered, 14.3 Mft^3 helium filled airship that is station kept at 70,000 ft altitude for power relay between ground and space is presented. The incident RF power at the 150 ft diameter by 1000 ft long platform is of order 1.5 MW. The dry mass of the vessel at 71% gross buoyancy is 38,500 lbs with a 150 ft diameter rectenna mass of 2500 lbs and a payload of 5500 lbs. The maximum stationkeeping power for 99 percentile winds over the continental US of 127 fps is about 500 kW or 672 horsepower for 80% efficient propellers driven by electric motors, assuming a drag coefficient of 0.035 and a fineness ratio of 6.7 for the airship. The ground based limited (±10°) steering 70m diameter beam waveguide antenna is fed from a linearly polarized array of injection phased-locked cooker tube magnetrons whose combined 4 MW output radiates through a fixed 45° venetian blind polarizing grid to render the field circularly polarized. Subsequently the radiated field continues in the beamed guide to another rotary polarizer which positions the final radiated linearly polarized antenna illumination The positionable linearly polarized field can track the weather vane cocking of the linearly polarized rectenna aboard the airship Alternatively, the positionable polarization capability can be used to vary the output power to the rectenna or another orthogonal polarized payload. The system tradeoff between the combination of capital costs and operating costs of power and cost of gain for the transmitting antenna is shown to be minimum when both are approximately equal. Because of the high altitude of the airship it is above most all of the weather and it can also extend the contact view time to low Earth orbiting spacecraft by a factor of three compared to ground based equipment. Consequently, laser or millimeter wavelength transmitters powered from the 2.45 GHz airship rectenna DC power output on be used to beam power in an all weather link to the orbiting space assets suitably equipped with photovoltaics or mm-rectennas, respectively. Other applications of the high altitude surrogate stationary satellite are for telecommunications and as an observation platform Telecommunications can encompass AM, FM and TV broadcasting, point of sale and inventory data relay, cellular telephones and paging for example. Observations from the platform can be for space, air, land and sea traffic monitoring and control, crop and weather watching, ice locations, border patrols, and astronomy.