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

Abstract

We describe the development of two circularly symmetric antennas with high polarization purity and low spillover. 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 levels of cross-polar leakage 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 0.73deg 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 test results show that the optics meet their design goals.

accepted for publication in IEEE Transactions on Antennas and Propagation

References in corpus (3)

• Planck Early Results: The Planck mission
• The C-Band All-Sky Survey: Instrument design, status, and first-look data
• The Cosmic Background Imager 2

Cited by in corpus (7)

• The C-Band All-Sky Survey (C-BASS): Design and capabilities
• C-Band All-Sky Survey: A First Look at the Galaxy
• The Second Radio Synchrotron Background Workshop: Conference Summary and Report
• The C-Band All-Sky Survey (C-BASS): Design and implementation of the northern receiver
• The C-Band All-Sky Survey (C-BASS): Template Fitting of Diffuse Galactic Microwave Emission in the Northern Sky
• The C-Band All-Sky Survey (C-BASS): Constraining diffuse Galactic radio emission in the North Celestial Pole region
• The C-Band All-Sky Survey (C-BASS): New Constraints on the Integrated Radio Spectrum of M 31