• Schinckel, Antony
• Cantrall, C.
• Brothers, Michael
• Broadhurst, Steve
• Cheng, Wan
• Beresford, Ron
• Forsyth, Ross
• Hotan, Aidan
• Hampson, Grant
• Kiraly, Dezso
• Leach, Mark
• Macleod, Adam
• Rispler, Adrian
• Doherty, Paul
• Barker, Steve
• Brown, Andrew

Abstract

We present the integration, laboratory testing, and field testing of the first full-size Mk II Phased-Array Feed (PAF) built for the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope.The ASKAP PAFs are a 94 port × 2 polarisation version of a planar connected “chequerboard” array (Hay and O’Sullivan, Radio Science, 43, no. 6, 2008).They operate over 0.7 GHz to 1.8 GHz and enable each 12 m ASKAP dish to observe a 30 deg2 field of view and survey the sky extremely rapidly.The Mk II PAF (Hampson et al., ICEAA, 2012, pp. 807-9) is designed to deliver significant improvements to noise performance, operability, and maintainability.It embraces RF-over-fibre (RFoF) to transport all signals back to the central building, vastly reducing the complexity of electronics and support systems located in the antenna pedestal.We describe the program of laboratory and field tests performed to validate the Mk II design and prepare it for production.First, we installed the PAF in a shielded room where we characterised the operating level, bandpass, and stability of all 188 RF paths including the new RFoF links.At this stage we also measured adjacent receiver chain isolation, tested electromagnetic shielding integrity, and checked for undesired electromagnetic emissions.Second, we performed aperture-array Y-factor noise performance measurements with the PAF on the ground, alternately observing the “cold” sky and a “hot” microwave absorber load.Third, we installed the PAF on ASKAP antenna 29 and are now using astronomical measurements to determine full-system performance.

Topics

• impedance spectroscopy