In addition, energy will be scattered by the terrain and by the rectenna surface. Rain and hail would be serious problems if the rectenna were located elsewhere than the California desert. To show the magnitude of rain, for example, statistics were gathered from the nearest site where records are kept. Rainfall data for Bakersfield, California are used as representative of rainfall to be found in the SPS receiving site vicinity (although it is still a considerable distance away and somewhat lower in elevation). Bakersfield receives rain at a rate of about 9.1 mm/hr on the average of about one hour per year, and at the extreme (one year out of 200) receives 17.3 mm/hr for one hour during a year. For about five minutes of an average year, Bakersfield receives rain at a rate of 19.3 mm/hr, and at 47.2 mm/hr at the one-out-of-200-year extreme for five minutes of that year. Based on the work of Dutton,* the height of a storm that will produce the aforementioned rain rates at the earth's surface can be predicted. The results are shown in Table 4.2 based on Bakersfield data for average conditions. These magnitudes could be of considerable importance to systems operating in such an environment. The amount of potential electromagnetic energy from all forms of scatter, including that from the rectenna itself (not calculated yet), added to the power from the sidelobes, presents a formidable problem for systems as far as 100 km from the rectenna. To assess the impact on systems near the Mojave site, an area 145 km by 145 km, with the proposed rectenna site at the center, was chosen as a data sample area. All government and nongovernment electromagnetic systems operating within this geographic boundary between 75 MHz and 5 GHz were tabulated. The active files showed 813 government systems and 685 civilian authorizations operational within these boundaries. Four purposes of this initial environmental assessment, the equipment/ system categories identified in the file retrieval are: Military Development and Operational Test and Evaluation • Instrumentation radars - conical scan and monopulse modes. • Traffic monitor/control radars. *Dutton, E.J., Precipitation Variability in the U.S.A, for Microwave Terrestrial System Desiyn, OT Report 77-134 (November 1977).
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