Accession Number : ADP004629

Title :   Controlled Surface Distortion Effects,

Corporate Author : ROME AIR DEVELOPMENT CENTER GRIFFISS AFB NY

Personal Author(s) : Jacavanco,D.

Report Date : JAN 1985

Pagination or Media Count : 24

Abstract : Results of a theoretical and experimental study of a technique that controls the level of the sidelobes in the far field pattern of a horn fed paraboloid are presented. The reflecting surface is intentionally distorted by mounting small circular disks on the dish and adjusting their height while monitoring the energy in the field at a specific angle. Patterns measured before and after show (a) localized sidelobe control on the order of 25 dB, little main beam distortion, and (c) acceptable overall sidelobe degradation. A theoretical model of a collapsed circular aperture containing the illumination due to the horn feed is used. The resulting aperture distribution is composed of three parts-the amplitude across the dish, and the amplitudes across each of the two disks. A computer subroutine duplicates the manual process of adjusting the disk position while monitoring the energy in the far field. There is good agreement between theory and experiment. (Author)

Descriptors :   *PARABOLIC ANTENNAS, *ANTENNA FEEDS, *SIDELOBES, FAR FIELD, SURFACE PROPERTIES, REFLECTORS, ENERGY

Distribution Statement : APPROVED FOR PUBLIC RELEASE