0191-9067/81/040355-12S02.00/0 Copyright ® 1981 SUNSAT Energy Council SPS SIMULATED EFFECTS OF IONOSPHERIC HEATING ON THE PERFORMANCE OF TELECOMMUNICATION SYSTEMS: A REVIEW OF EXPERIMENTAL RESULTS CHARLES M. RUSH National Telecommunications and Information Administration Institute for Telecommunication Sciences Boulder, Colorado 80303, USA Abstract — The microwave power beam that is associated with the operation of the Satellite Power System (SPS) will provide a continuous source of power into the Earth's ionosphere. As currently conceptualized, the power density at the center of the beam would be 23 mW/cm2. This power density may be of sufficient magnitude to give rise to changes in the structure of the ionosphere and to increases in the electron temperature in the ionosphere. This review describes the work that was undertaken to assess the degree to which the ionosphere and ionospheric-dependent telecommunication systems may be impacted by the passage of the satellite power system microwave power beam. The results of these numerous investigations are summarized and areas in which further study is required are pointed out. It is concluded that the operation of a single SPS will not adversely impact the performance of telecommunication systems whose frequencies are in the very low, low, and medium frequency portion of the spectrum. Initial results obtained at higher frequencies, however, particularly VHF satellite-to-ground signals, indicate that these systems may be affected by operational solar power satellites. 1. INTRODUCTION — GENERAL BACKGROUND The United States Department of Energy is currently investigating a number of different alternatives in order to meet the energy needs of the nation in the twenty- first century. One of the alternatives currently under study centers around a satellite power system (SPS) or solar power satellite as it is commonly referred to. The current system concept with regard to the SPS is the placing into geostationary orbit of one or more satellites equipped with photovoltaic cells to produce direct current from solar radiant energy. A reference system concept has been defined to serve as a common basis for research and evaluation (1). Each satellite, which will be 10 km long, 5 km wide, and 0.5 km thick, would be equipped with instrumentation to transform the direct current produced by solar photovoltaic cells to microwave energy at the satellite. The microwave energy would be transmitted to the surface of the Earth at a frequency of 2.45 GHz. This frequency falls within an industrial, scientific, and medical band (ISM) allocation of the electromagnetic spectrum. At the surface of the earth, the microwave energy would be rectified and conditioned to interface with utility grids. The input into the utility grid would be about 5000 MW of continuous power for each satellite/rectenna combination. In its quest to obtain a viable program directed toward investigating the overall feasibility of a satellite power system, the Department of Energy has conducted an environmental assessment of the impact of the SPS operation. In this paper, the
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