Accession Number : AD0283480

Title :   REFOCUSING OF LARGE ANTENNAS FOR PATTERN MEASUREMENTS

Corporate Author : WHEELER LABS INC GREAT NECK N Y

Personal Author(s) : KAPLAN,ROBERT A.

Report Date : DEC 1958

Pagination or Media Count : 1

Abstract : For large, narrow-beam antennas, the min test range on which far-field patterns can be measured is very large. With fixed antennas, this large range requirement makes pattern testing difficult even by flying. One method of simplifying testing is by refocusing the antenna on a point in the intermediate field resulting in a shorter range. It is shown that, near the focal point, the observed patterns are similar to the far-field pattern, thus enabling far-field patterns to be measured at a reduced range. The refocusing technique is analyzed to indicate the region in space in which it is valid and to determine the accuracy of the resulting patterns. Numerical calculations are given to illustrate the effects of refocusing in two specific cases. The results of these calculations indicate that far-fiel patterns can be measured at very small ranges with small increase in level of sidelobes and nulls for pattern angles out to 45 degrees from the beam axis. (Author)

Descriptors :   *ANTENNA RADIATION PATTERNS, AMPLITUDE MODULATION, ANTENNA COMPONENTS, ANTENNAS, ILLUMINATION, PHASE SHIFT CIRCUITS

Distribution Statement : APPROVED FOR PUBLIC RELEASE