Directivity optimization of a reflector antenna with cluster feeds: A closed-form solution

Author

Lam, Peter T. ; Lee, Shung-wu ; Chang, Donald C D ; Lang, K.C.

Author_Institution

Dept. of Elec. and Comp. Eng., Univ. of Illinois, Urbana, IL, USA

Volume

33

Issue

11

fYear

1985

fDate

11/1/1985 12:00:00 AM

Firstpage

1163

Lastpage

1174

Abstract

The directivity of a reflector antenna deteriorates as the feed moves away from the focal point for beam scanning. This deterioration can be substantially reduced if a cluster feed instead of a single feed is used to control a beam. A closed-form solution is presented for the cluster excitation to achieve the optimum directivity. For an offset $108 \\lambda$ parabolic reflector scanning 10 beamwidths, the optimum-directivity achieved by a 19-element (seven-element) cluster is 12 dB (8 dB) higher than that of a single element. Comparison of the optimum-directivity design and the popular conjugate field matching design is made. When the cluster spacing $d$ is greater than $1 \\lambda$ , it is found that the optimum directivity is higher than that of conjugate field matching (CFM) scheme by an insignificant amount, although the excitations of two designs can be quite different. For $d < 0.5 \\lambda$ , the optimum design may exhibit the supergain phenomenon, namely, extremely high directivities achieved by an oscillatory cluster excitation.

Keywords

Planar arrays; Reflector antenna feeds; Reflector antennas, multireflector; Aircraft propulsion; Antenna arrays; Antenna feeds; Closed-form solution; Costs; Geometry; Optimization methods; Phased arrays; Radar antennas; Reflector antennas;

fLanguage

English

Journal_Title

Antennas and Propagation, IEEE Transactions on

Publisher

ieee

ISSN

0018-926X

Type

jour

DOI

10.1109/TAP.1985.1143516

Filename

1143516