Implementation of an optimized Cassegrain system for radio telescopes

Journal article

We present the antenna design for a radio interferometer, the Arcminute Microkelvin Imager, together with its beam pattern measurement. Our aim was to develop a low-cost system with high aperture efficiency and low ground spill across the frequency range 12-18 GHz. We use a modified Cassegrain system consisting of a commercially available paraboloidal primary mirror with a diameter of 3.7 m, and a shaped secondary mirror. The secondary mirror is oversized with respect to a ray optics design and has a surface that is bent towards the primary near its outer edge using a square term for the shaping. The antennas are simple to manufacture and therefore their cost is low. The design increased the antenna gain by approximately 10 per cent compared to a normal Cassegrain system while still maintaining low contamination from ground spill and using a simple design for the horn. © 2008 RAS.

Authors: Holler, C; Hills, R; Jones, M; Grainge, K; Kaneko, T

• Publication status: Published
• Journal: Monthly Notices of the Royal Astronomical Society
• Volume: 384
• Issue: 3
• Pages: 1207-1210
• Publication date: 2008-03-01
• DOI: 10.1111/j.1365-2966.2007.12792.x
• EISSN: 1365-2966
• ISSN: 0035-8711
• Language: English
• Keywords: telescopes; instrumentation : interferometers; techniques : interferometric