A Broadband Circularly Polarized Waveguide Antenna Design for Low Cross-Polarization

Ryoji YAMAUCHI
Takeshi FUKUSAKO

Publication
IEICE TRANSACTIONS on Communications   Vol.E99-B    No.10    pp.2187-2194
Publication Date: 2016/10/01
Publicized: 2016/04/19
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2015EBP3544
Type of Manuscript: PAPER
Category: Antennas and Propagation
Keyword: 
broadband antenna,  circular waveguide antenna,  circular polarization,  cross-polarization,  L-shaped probe,  axial ratio,  

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Summary: 
An L-shaped probe with a surrounding aperture such as a waveguide can generate circular polarization (CP) waves. Circular waveguide antennas using an L-shaped probe have broadband characteristics both in axial ratio (AR) and in input impedance, however cross-polarization (XPOL) is easily generated due to its asymmetrical structure resulting in a radiation pattern that has narrow CP azimuth range. In this paper, design techniques to reduce the XPOL generated from a circular waveguide antenna using an L-shaped probe are proposed. As a result, XPOL is reduced by around 10 dB, and CP is radiated over a wide angle range of 120-150° covering frequencies from 7.35 to 9.75GHz.