Scalar horn with shaped lens improves Cassegrain efficiency

Author

Kildal, Per-Simon ; Jakobsen, Kurt R.

Author_Institution

Norwegian Institute of Technology, Trondheim, Norway

Volume

32

Issue

10

fYear

1984

fDate

10/1/1984 12:00:00 AM

Firstpage

1094

Lastpage

1100

Abstract

It is shown that the aperture efficiency of a classical Cassegrain antenna can be considerably improved if the radiation pattern of the feed is optimally shaped. The corresponding optimum field distribution Over the aperture of the feed consists of a circular main lobe which is surrounded by concentric sidelobe rings. This optimum field distribution with one sidelobe ring included is realized by shaping of a dielectric lens which is positioned in the aperture of a corrugated horn antenna. The design can provide a theoretical aperture efficiency of 90.5 percent when subreflector diffraction and aperture shadowing are neglected, i.e., an improvement of 0.4 dB compared to an optimum conventional feed. Measurements of a model at 22.8 GHz gave a practical result of 85.6 percent. If the model is used to feed a 30 m radiotelescope the overall antenna efficiency becomes about 71 percent.

Keywords

Corrugated horn antennas; Horn antennas, corrugated; Lens antennas; Reflector antennas, multireflector; Antenna feeds; Antenna radiation patterns; Aperture antennas; Dielectrics; Diffraction; Frequency; Lenses; Reflector antennas; Satellite communication; Shadow mapping;

fLanguage

English

Journal_Title

Antennas and Propagation, IEEE Transactions on

Publisher

ieee

ISSN

0018-926X

Type

jour

DOI

10.1109/TAP.1984.1143205

Filename

1143205