Preliminary design of eleven feed for SKA band 1

Many challenges are in the design of a feed for reflector antennas in SKA project, such as high aperture efficiency, low noise temperature, low cross-polar level, good circularity of the far-field function, and a very compact size. We present a new design of the Eleven feed as a candidate for SKA band 1 (0.35-1.05 GHz). The configuration of the feed can be for dual polarization either four ports with four single ended low noise amplifiers (LNAs) or two differential LNAs, or two ports with a balun and two single-ended LNAs. The typical performances of the feed over the whole band are: -12 dB reflection coefficient, 60% ~ 70% aperture efficiency, -15 relative cross-polar level, 0.05 dB ohmic loss and a size of 750×250 mm².