DocumentCode :
1038191
Title :
Low-loss offset feeds for electrically large symmetric dual-reflector antennas
Author :
Veruttipong, Thavath ; Galindo-israel, Victor ; Imbriale, William A.
Author_Institution :
Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA USA
Volume :
35
Issue :
7
fYear :
1987
fDate :
7/1/1987 12:00:00 AM
Firstpage :
745
Lastpage :
755
Abstract :
Circularly symmetric, dual-reflector, high-gain antenna systems often require feeds placed off the system´s axis because of the need for multiple feeds to use the reflector antenna. Also, the constraint requiring the hyperboloid or shaped subreflector to remain circularly symmetric is sometimes added. In a Cassegrainian system, the subreflector and feed may be rotated off-axis around the paraboloid focus and retain main reflector focusing. However, substantial spillover results in considerable noise in a high-gain/low-noise temperature system. In a shaped system, the tilt of the shaped subreflector and feed together results in substantial defocusing as well as spillover noise. If the subreflector is tilted approximately one-half the angle of the feed tilt in either the Cassegrainian or the dual-shaped reflector antenna, it is found that spillover and noise are substantially reduced with tolerable defocusing. An extensive numerical analysis of these effects was conducted to determine the characteristics of a 70-meter, dual-shaped reflector versus Cassegrainian antenna and to gain some understanding of the cause of the observed effects.
Keywords :
Offset reflector antennas; Reflector antennas, offset; Antenna feeds; Antennas and propagation; Geometry; Laboratories; Noise reduction; Noise shaping; Numerical analysis; Propulsion; Reflector antennas; Space technology;
fLanguage :
English
Journal_Title :
Antennas and Propagation, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-926X
Type :
jour
DOI :
10.1109/TAP.1987.1144182
Filename :
1144182
Link To Document :
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