| 27th of February 2015 |
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| ASKAP Highlights - Mk II Phased-Array Feed Performance |
| by Aaron Chippendale (CASS) |
| On-dish measurements from CSIRO's Mk II
phased-array feed (PAF) have confirmed low-noise performance across the ASKAP
frequency band. Sensitivity is significantly improved over the majority of
the band and is doubled above 1.4 GHz compared to the Mk I PAF. A minimum
system-temperature-on-efficiency (Tsys/η) of 78 K is reached
at 1.23 GHz, and 95 K or better across the 0.835 to 1.8 GHz range. The gaps
in the data at certain frequencies are due to radio transmissions from
satellites that are stronger than Taurus A, the astronomical calibration
source used for the above single dish measurement. The improvement was achieved via more accurate experimental characterisation of the low-noise amplifier signal and noise parameters, and enhancement of the chequerboard array to better match these parameters. |