THE VARR METHOD: A TECHNIQUE FOR DETERMINING THE EFFECTIVE POWER PATTERNS OF MILLIMETER-WAVE RADIOMETRIC ANTENNAS,
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
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The VARR VAriable Range Reflector Method is a technique which has been developed to measure the effective power patterns of millimeter-wave radiometric antennas. In this method, a large movable metallic surface is oriented to reflect radiation from the zenith into an antenna which is directed along the horizontal. Radiometric temperature is measured as a function of the range of the reflect4r from the antenna. In addition, the water vapor content of the atmosphere and the radiometric temperatures in the directions of background and zenith are observed. A computing procedure has been devised to determine the complete pattern and gain characteristics of the antenna system purely on the basis of data provided by the measuring system. The method has been used to successfully determine the effective power patterns of a number of antenna systems. These results form the basis of a comparative evaluation of antenna system performance that is in substantial agreement with the observed effectiveness of these same antennas in previous measurements.
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