Accession Number : AD0776252

Title :   Characteristics of the NLRO 18.3 Meter Parabolic Antenna at 400 MHz,

Corporate Author : IOWA UNIV IOWA CITY DEPT OF PHYSICS AND ASTRONOMY

Personal Author(s) : Benson,John M. ; Shawhan,Stanley D.

Report Date : FEB 1974

Pagination or Media Count : 88

Abstract : Measurements were carried out on the 18.3 meter University of Iowa parabolic reflecting antenna using radioastronomical techniques at 400 MHz. The antenna beam pattern was found to be unsymmetrical with half-power widths of 2.75 degrees by 2.25 degrees. The aperture illumination provided by the log-periodic feed antenna is mainly responsible for a total aperture efficiency of 36%. The gain of the reflector antenna is 33.2 dB and its directivity is 33.7 dB. The most prominent side-lobes were observed to be at least 25dB down from the maximum response. The surface of the paraboloidal reflector itself has an rms deviation of approximately 1 cm from a true paraboloid. In terms of radio astronomy, the antenna perfromance factor is 0.034 K of antenna temperature per flux unit (10 to the minus 26th power watts/sq m/Hz). The pointing accuracy was found to vary randomly within plus or minus 0.25 degrees in elevation and azimuth. (Modified author abstract)

Descriptors :   *Parabolic antennas, *Radio telescopes, Ultrahigh frequency, Antenna apertures, Efficiency, Gain, Aiming, Accuracy

Subject Categories : Astrophysics
      Electrical and Electronic Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE