Accession Number:

AD0649707

Title:

OPTIMUM PARABOLOID AERIAL DESIGN,

Descriptive Note:

Corporate Author:

SIGNALS RESEARCH AND DEVELOPMENT ESTABLISHMENT CHRISTCHURCH (ENGLAND)

Personal Author(s):

Report Date:

1966-09-01

Pagination or Media Count:

24.0

Abstract:

A computer study was made of the spillover, cross polarization and illumination efficiency of paraboloids of various FD ratios focal lengthparaboloid diameter fed by rectangular, square and circular waveguides in their lowest order modes. The feed radiation patterns used were those derived by simple diffraction theory, from the incident waveguide-mode field distribution. The approximations made in this derivation give unnaturally low spillover for very small aperture feeds and thus favour short FD systems which would use such feeds. The feed dimensions were optimised to give maximum merit gaintotal noise temperature for each combination of feed, receiver noise temperature and FD ratio. The optimum horn dimensions and resulting illumination tapers, excess aerial noise temperatures, gain efficiencies and merit, produced by the computations are presented. The results show amongst other things that the merit of a low FD system is about 0.8 dB less than that of a large FD system. They also show that, if the system has a low receiver temperature, the feed dimensions should be larger than conventional design procedures indicate, to give up to 3 dB more edge illumination taper. Author

Subject Categories:

  • Electrical and Electronic Equipment

Distribution Statement:

APPROVED FOR PUBLIC RELEASE