The bandwidth of helical antennas

Author

Maclean, T.S.M. ; Kouyoumjian, R.G.

Author_Institution

Ohio State University, Columbus, OH, USA

Volume

7

Issue

5

fYear

1959

fDate

12/1/1959 12:00:00 AM

Firstpage

379

Lastpage

386

Abstract

The propagation along a finite helix is examined by using a propagation constant which was determined by Sensiper for the infinite helix. By utilizing the Hansen and Woodyard condition, the bandwidth variation with the dimensions of the helix is obtained. It is shown that for a pitch angle $\\psi$ equal to $13\\deg$ , the normally accepted bandwidth of $0.77 < C_{\\lambda } < 1.25$ , where $C_{\\lambda }$ is the circumference in terms of free-space wavelengths, is applicable only to antennas up to about two wavelengths long. A curve showing the bandwidth as a function of length has been computed, and the shape of this curve has been confirmed experimentally. Good patterns and axial ratio with sidelobe levels no greater than -10 db were obtained for helices as long as 10 wavelengths. Good patterns and axial ratio may also be obtained for $\\psi$ as small as $2\\deg$ provided that the helix is sufficiently long to establish the surface wave.

Keywords

Helical antennas; Antennas and propagation; Bandwidth; Conductors; Equations; Helical antennas; Propagation constant; Shape; Surface waves; Wounds; Yagi-Uda antennas;

fLanguage

English

Journal_Title

Antennas and Propagation, IRE Transactions on

Publisher

ieee

ISSN

0096-1973

Type

jour

DOI

10.1109/TAP.1959.1144758

Filename

1144758