RFI due to continuous operation of the microwave beam has been examined in this task. Transients associated with start-up, shut-down, and physical interference due to clouds, aircraft, and the onset of shadowing by the Earth will have to be investigated in future studies. Data, control, and command links will have to be included in future investigations of RFI and associated frequency allocation. The phase front was assumed to be controlled by a system similar to that described in Reference 38. It was further assumed that 90% of the power could be collected within the main lobe. This assumption can be realized by relatively simple distribution of power density illumination across the transmitting antenna (see “Effects of SSPS RFI on Other Users” later in this chapter). Near optimum orbital locations were selected in an equatorial synchronous orbit at 123° W and 57° E Longitude based on reducing propellant requirements for RCS units. Near optimum ground locations were selected in the southwest desert area, 33° N Latitude, 113° 30' W Longitude for further specific investigations. These investigations concerned the RFI associated with the fundamental power transfer beam, including its side lobes, its noise, spurious signals, and harmonics, and cover primarily the continuous operations phase as compared to start, stop, and failure transients. Their purpose was to delineate the approaches which would reduce RFI and to provide an outline for subsequent studies. Discussion. — a. Orbital Location The SSPS should be located at the stable node in equatiorial synchronous orbit (e.g., ~123°W Longitude), primarily for station keeping purposes. If a satellite the size of the SSPS should lose its activity ability to station-keep at synchronous altitude and start moving around in orbit, it would sweep out large regions that may be occupied. “Rules of the Road” will undoubtedly be evolved which will dictate that the smaller (spacecraft proportions) most maneuverable spacecraft shall “give way” to the largest, most unmaneuverable spacecraft. I After the first prototype has become operational, additional antennas and solar arrays could be added to an SSPS. A similar set could be located at the second stable node at ~ 57° E Longitude. After sufficient confidence is gained, SSPS's could be located at other points and rely on active station-keeping systems. RFI induced by an SSPS will affect its close neighbors in orbit. This effect is discussed in “Effects of SSPS RFI on Other Users” later in this chapter. b. Ground Location The guidelines associated with receiving antenna locations in the vicinity of four selected high power-consuming areas were set up as follows:
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