1.2 Meter Shielded Cassegrain Antenna for Close-Packed Radio Interferometer
Abstract
Interferometric millimeter observations of the cosmic microwave background and clusters of galaxies with arcmin 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 TiO top layer for protection. A low beam sidelobe level is achieved with a Gaussian feed illumination pattern with edge taper, designed based on feedhorn antenna simulations and verified in a far field beam pattern measurement. A shielding baffle reduces inter-antenna 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 per year is anticipated in a 13-element array operation.
Keywords
Cite
@article{arxiv.1012.3899,
title = {1.2 Meter Shielded Cassegrain Antenna for Close-Packed Radio Interferometer},
author = {Patrick M. Koch and Philippe Raffin and Yau-De Huang and Ming-Tang Chen and Chih-Chiang Han and Kai-Yang Lin and Pablo Altamirano and Christophe Granet and Paul T. P. Ho and Chih-Wei L. Huang and Michael Kesteven and Chao-Te Li and Yu-Wei Liao and Guo-Chin Liu and Hiroaki Nishioka and Ching-Long Ong and Peter Oshiro and Keiichi Umetsu and Fu-Cheng Wang and Jiun-Huei Proty Wu},
journal= {arXiv preprint arXiv:1012.3899},
year = {2015}
}
Comments
35 pages, 14 figures; accepted for publication in PASP