1.2 m Shielded Cassegrain Antenna for Close-Packed Radio Interferometer
Journal
Publications of the Astronomical Society of the Pacific
Journal Volume
123
Journal Issue
900
Pages
198-212
Date Issued
2011
Author(s)
Koch, Patrick M.
Raffin, Philippe
Huang, Yau-De
Chen, Ming-Tang
Han, Chih-Chiang
Lin, Kai-Yang
Altamirano, Pablo
Granet, Christophe
Ho, Paul T. P.
Huang, Chih-Wei L.
Kesteven, Michael
Li, Chao-Te
Liao, Yu-Wei
Liu, Guo-Chin
Nishioka, Hiroaki
Ong, Ching-Long
Oshiro, Peter
Umetsu, Keiichi
Wang, Fu-Cheng
Abstract
Interferometric millimeter observations of the cosmic microwave background and clusters of galaxies with arcminute resolutions require antenna arrays with short spacings. Having all antennas co-mounted on a single steerable platform sets limits to the overall weight. A 25 kg lightweight novel carbon-fiber design for a 1.2 m diameter Cassegrain antenna is presented. The finite element analysis predicts excellent structural behavior under gravity, wind, and thermal load. The primary- and secondary-mirror surfaces are aluminum-coated with a thin TiO2 top layer for protection. A low beam sidelobe level is achieved with a Gaussian feed-illumination pattern with edge taper, designed based on feed-horn antenna simulations and verified in a far-field beam-pattern measurement. A shielding baffle reduces interantenna coupling to below ∼- 135 dB. The overall antenna efficiency, including a series of efficiency factors, is estimated to be around 60%, with major losses coming from the feed spillover and secondary blocking. With this new antenna, a detection rate of about 50 clusters yr-1 is anticipated in a 13-element array operation. © 2011. The Astronomical Society of the Pacific.
SDGs
Type
journal article