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A STUDY OF VOR REFLECTION CHARACTERISTICS
NATIONAL AVIATION FACILITIES EXPERIMENTAL CENTER ATLANTIC CITY N J
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Frequently a VHF omnidirectional range VOR station must be located at a site which is far from desirable. The 4-loop VOR installation at Charleston, S. C., was situated at the center of a 2,000-ft-diameter cleared space in a wooded area. The station could not be commissioned because of excessive course scalloping, and the condition was not improved greatly even by mounting the antenna system on top of a 75-fthigh counterpoise 150 ft in diameter. Tests were conducted with a vertical screen made of horizontal wires to determine the effectiveness of a large counterpoise 75 ft high in reducing scalloping caused by reflecting objects beyond 1,000 ft from a VOR antenna. It is recommended that no further consideration be given to using a counterpoise 150 ft in diameter and 75 ft high for reducing course scalloping caused by objects greater than 1,000 ft away from a 4-loop VOR antenna. Author
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