DEVELOPMENT AND TESTING OF HF WIRE-GRID LENS ANTENNA. VOLUME 2
TRG INC MENLO PARK CA
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The report describes the results of a Joint Services Evaluation conducted in the Spring and Summer of 1964 on the first full-scale model of the Wire-Grid Lens HF Antenna, constructed for the FAA at their International Flight Service Receiver Station at Molokai, Hawaii. The lens employs a novel focusing medium consisting of two wire grids, one above the other, whose wave slowing or refractive characteristics are to first order independent of frequency. By locating feeds at many different points on the lens circumference, it becomes equivalent to many highly directive broad-band antennas pointed in many different directions. During the evaluation SRI and NRL made an extensive series of airborne pattern measurements on the lens, the FAA station rhombics, and several reference antennas using the SRI airborne pattern measuring equipment. These data were later reduced by SRI with aid of a computer to the form presented in this report. These patterns demonstrate the predicted directivity and beam forming properties of the lens at all azimuth angles over its 3 to 30 Mc design frequency band, which are comparable to those of the station rhombics over the 5 to 25 Mc band each of which operates over a more restricted frequency band.
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