A Wide-band Feed System for SKA Band 1 Covering Frequencies From 350 - 1050 MHz

Paper i proceeding, 2016

We present the design of a wideband feed system for the Band 1 of the Square Kilometer Array (project). The Band 1 feed system uses a quad-ridged flared horn (QRFH) optimized for a offset Gregorian dual reflector dish to cover RF frequencies from 350 - 1050 MHz, and a cryogenic low noise amplifier (LNA). The feed horn is optimized to achieve best Aeff/Tsys over the entire band, by making trade-off between aperture efficiency and spill over noise contribution. The optimised feed horn shows above 70% efficiency over the entire 3:1 band, with return loss better than 10 dB. The cryostat following the feed has between 9 to 14 K noise, measured at the co-axial connector of the QRFH. The estimated on-sky sensitivity of the feed system is better than specified 4.2 m2/K averaged over the entire frequency band.