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18th of September 2018
ASKAP composite feed leg trials
Commissioning of the ASKAP antennas has revealed that the system temperatures of the Phased Array Feeds (PAFs) are not quite as low as had been expected. Two possible contributing factors are blockage of the dish surface by the feed legs (which support the PAF in the focal plane), and scattering of extraneous radio emission from the feed legs onto the PAF. In order to investigate the effects of these, one ASKAP antenna has had its steel feed legs replaced by legs constructed from a non-conducting, fibre-glass composite material, which are effectively transparent at radio wavelengths and will result in less blockage and scattering. The image above shows the process of replacing the existing feed legs with the new materials, a process (including the removal of the PAF in advance of feed leg changeover, and subsequent reinstallation) which took several days. Observations are now underway to characterise the improvement in performance.

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