Design and Analysis of a 3-Arm Spiral Antenna

A novel 3-arm spiral antenna structure is presented in this paper. This antenna similar to traditional two-arm or four-arm spiral antennas exhibits wideband radiation characteristic and circular polarization. Advantages offered by the new design are two fold. Unlike the traditional spiral antennas t...

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Bibliographic Details
Published in:IEEE transactions on antennas and propagation 2007-02, Vol.55 (2), p.258-266
Main Authors: Muller, D.J., Sarabandi, K.
Format: Article
Language:English
Subjects:
Antenna feeds
Antennas
Applied sciences
Arm
Baluns
Broadband antennas
Circular polarization
Coaxial components
Computer simulation
Coplanar transmission lines
Coplanar waveguides
Exact sciences and technology
Impedance matching
Polarization
Radiocommunications
Spiral antennas
Spirals
Studies
Telecommunications
Telecommunications and information theory
Transmission line antennas
Transmission lines
unbalanced spiral
Wideband
wideband antenna
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Description
Summary:A novel 3-arm spiral antenna structure is presented in this paper. This antenna similar to traditional two-arm or four-arm spiral antennas exhibits wideband radiation characteristic and circular polarization. Advantages offered by the new design are two fold. Unlike the traditional spiral antennas the three-arm spiral can be fed by an unbalanced transmission line, such as a coaxial line or coplanar waveguide, and therefore an external balun is not needed at the feed point. Also by proper choice of arms' dimensions the antenna can be directly matched to any practical transmission line characteristic impedance and therefore external matching networks are not required. This is accomplished by feeding the antenna at the outer radius by a coplanar waveguide (CPW) transmission line and tapering it towards the center. The antenna can also be fed from the center using a coaxial or CPW line perpendicular to the plane of the spiral antenna. A full-wave numerical simulation tool is used to optimize the geometry of the proposed 3-arm spiral to achieve a compact size, wide bandwidth operation, and low axial ratio. The antenna is also designed over a ground plane to achieve a unidirectional radiation and center loading is examined that improves the axial ratio. Simulated results like return loss, radiation pattern, gain, and axial ratio are compared with those obtained from measurements and good agreements are shown. Because of its unique feed structure and compact size, application of the proposed 3-arm spiral antenna for wideband array applications is demonstrated
ISSN:0018-926X
1558-2221
DOI:10.1109/TAP.2006.889798