Two-arm eccentric spiral antenna

Author

Gloutak, Ronald T., Jr. ; Alexopoulous, N.G.

Author_Institution

Northrop Corp., Pico Rivera, CA, USA

Volume

45

Issue

4

fYear

1997

fDate

4/1/1997 12:00:00 AM

Firstpage

723

Lastpage

730

Abstract

This paper presents a free-space analysis of a planar two-arm eccentric spiral antenna. The eccentricity generates a circularly polarized wave with the main beam directed off-normal to the spiral plane. Input impedance and radiation characteristics are calculated from the current distribution generated by a method of moments solution. The radiation characteristics include power gain and axial ratio patterns. Three-dimensional (3-D) gain surface plots illustrate off-normal dependence of the eccentricity constant. The eccentric spiral antenna is found to have a significant increase in gain. This occurs when adjacent spiral arms rotating 360° have an electrical length increase of one wavelength. Thus, adjacent currents on one side of the spiral are nearly all in-phase. On the opposite side of the spiral, all neighboring currents are nearly out-of-phase. Evaluation of these currents result in a theory of operation for eccentric spiral antennas

Keywords

antenna radiation patterns; current distribution; electric impedance; electromagnetic wave polarisation; method of moments; spiral antennas; 3D gain surface plots; antenna theory; axial ratio patterns; circularly polarized wave; current distribution; eccentricity constant; electrical length; free-space analysis; input impedance; method of moments solution; off-normal mainbeam; planar two-arm eccentric spiral antenna; power gain; radiation characteristics; spiral plane; wavelength; Antenna theory; Arm; Current distribution; Dipole antennas; Frequency; Geometry; Moment methods; Polarization; Spirals; Surface impedance;

fLanguage

English

Journal_Title

Antennas and Propagation, IEEE Transactions on

Publisher

ieee

ISSN

0018-926X

Type

jour

DOI

10.1109/8.564099

Filename

564099