SATELLITE POWER SYSTEM RECTENNA SITING STUDY by James B. Blackburn, Jr. and Bill A. Bavinger Rice University This study was undertaken by the authors in association with Allan D. Kotin of Kotin and Regan of Los Angeles, California. The goal of this study was to determine if potential sites for receiving antennas existed within the Continental United States. A receiving antenna located at 35 degrees north latitude would require the dedication of approximately 35,000 acres to the elliptical rectenna and associated buffer zone (vertical dimension - 15.8 km; horizontal dimension - 12.0 km). The SPS reference design contemplates the development of 60 receiving antennas within the Continental United States over a 30 year time frame. Our approach to site availability was to eliminate areas as sites rather than attempting to locate sites. Three classifications of land use constraints were developed. These were (1) areas absolutely excluded, (2) areas potentially excluded, and (3) areas exhibiting characteristics that would exclude the reference-system rectenna but were available if design modifications were made. Data was gathered depicting the spatial coverage of variables within the three classifications. In all, 37 variables were mapped. Many variables were comprised of several gradients which were mapped separately. In all, 67 data items (excluding states and electrical reliability council regions) were mapped. Fifteen variables were classified as absolute exclusion variables, 21 were classified as potential exclusion variables and 30 were classified as design/cost variables. To display the data, a base map was developed. This map used the Albers Equal Area Projection System and was overlain by 92,512 grid squares; 52,479 grid squares covered the Continental United States. The northen- most grid squares were 14 km vertically and 9.2 km wide while the southernmost grid squares were 14 km vertically and 12.2 km wide. The size of the grid square generally approximated the size of the rectenna with a buffer zone. Each grid square corresponds exactly with a United States Geographical Survey 7 1/2 minute quadrangle map. Each data item was mapped as being present or absent within a grid cell. Through the use of a Tektronic graphics tablet, the mapped information was transferred to the Rice University computer system. Subsequent analyses were conducted using the Rice Architecture Geographic Information System (RAGIS). RAGIS has more than 250 special operations for geographic information processing and utilizes a host language called Speakeasy to support and control its operations. Through the use of RAGIS, a series of analyses were undertaken to determine the availability of sites for receiving antennas. The basic analytical tool involved the overlaying of 15 absolute exclusion variables to determine the extent of their spatial coverage. These 15 absolute exclusion variables were (1) inland waters, (2) Stan-
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