A Caltech Library Service

A Circularly Symmetric Antenna Design With High Polarization Purity and Low Spillover

Holler, Christian M. and Taylor, Angela C. and Jones, Michael E. and King, Oliver G. and Muchovej, Stephen J. C. and Stevenson, Matthew A. and Wylde, Richard J. and Copley, Charles J. and Davis, Richard J. and Pearson, Timothy J. and Readhead, Anthony C. S. (2013) A Circularly Symmetric Antenna Design With High Polarization Purity and Low Spillover. IEEE Transactions on Antennas and Propagation, 61 (1). pp. 117-124. ISSN 0018-926X. doi:10.1109/TAP.2012.2219843.

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item:


We describe the development of two circularly symmetric antennas with high polarization purity and low spill-over. Both were designed to be used in an all-sky polarization and intensity survey at 5 GHz (the C-Band All-Sky Survey, C-BASS). The survey requirements call for very low cross-polar signal levels and far-out sidelobes. Two different existing antennas, with 6.1-m and 7.6-m diameter primaries, were adapted by replacing the feed and secondary optics, resulting in identical beam performances of 0.73° FWHM, cross-polarization better than - 50 dB, and far-out sidelobes below -70 dB. The polarization purity was realized by using a symmetric low-loss dielectric foam support structure for the secondary mirror, avoiding the need for secondary support struts. Ground spill-over was largely reduced by using absorbing baffles around the primary and secondary mirrors, and by the use of a low-sidelobe profiled corrugated feedhorn. The 6.1-m antenna and receiver have been completed and tested. Results show that the co-polar beam matches the design simulations very closely in the main beam and down to levels of - 80 dB in the backlobes. With the absorbing baffles in place the far-out ( >; 100°) sidelobe response is reduced below -90 dB. Cross-polar response could only be measured down to a noise floor of - 20 dB but is also consistent with the design simulations. Temperature loading and groundspill due to the secondary support were measured at less than 1 K.

Item Type:Article
Related URLs:
URLURL TypeDescription
Jones, Michael E.0000-0003-3564-6680
Pearson, Timothy J.0000-0001-5213-6231
Readhead, Anthony C. S.0000-0001-9152-961X
Additional Information:© 2012 IEEE. Manuscript received November 11, 2011; revised March 21, 2012; accepted July 02, 2012. Date of publication September 19, 2012; date of current version December 28, 2012. This work was supported in part by NSF grants AST-0607857 and AST-1010024, and in part by the University of Oxford Department of Physics. The work of A. C. Taylor was supported by a Royal Society Dorothy Hodgkin Fellowship. The authors would like to thank the staff of the Mechanical Engineering group in the Oxford University Department of Physics, particularly M. Tacon, P. Rossiter and M. Brock, for the construction of the C-BASS optical components. They also thank the staff of the Owens Valley Radio Astronomy Observatory, particularly R. Keeney, for support of the operations of the C-BASS North telescope.
Funding AgencyGrant Number
University of OxfordUNSPECIFIED
Subject Keywords:Antenna measurements, antenna radiation patterns, radio astronomy, reflector antennas
Issue or Number:1
Record Number:CaltechAUTHORS:20130125-141315778
Persistent URL:
Official Citation:Holler, C.M.; Taylor, A.C.; Jones, M.E.; King, O.G.; Muchovej, S.J.C.; Stevenson, M.A.; Wylde, R.J.; Copley, C.J.; Davis, R.J.; Pearson, T.J.; Readhead, A.C.S.; , "A Circularly Symmetric Antenna Design With High Polarization Purity and Low Spillover," Antennas and Propagation, IEEE Transactions on , vol.61, no.1, pp.117-124, Jan. 2013 doi: 10.1109/TAP.2012.2219843
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36600
Deposited By: Ruth Sustaita
Deposited On:25 Jan 2013 22:35
Last Modified:09 Nov 2021 23:23

Repository Staff Only: item control page