System noise calculations over the decade bandwidth of the eleven feed for radio telescope applications

Wideband systems forms an integral part of future radio astronomical and geodetic research [1, 2]. Fast comparisons between and of systems capabilities is required for planning and evaluation. This paper presents calculations, and theoretical A/T curves, for cryogenic and ambient system implementations using the Eleven feed and similar band LNAs. The Eleven feed is a decade band antenna and, similar band low noise amplifiers options, developed at Caltech and Chalmers are used for the model. The Chalmer's LNA is designed for use at room temperature, and the Caltech LNA, cryogenic temperatures. The achievable SNR of a radio telescopes is a product of the sensitivity of the receiver and achievable gain. Commonly expressed as a single figure of merit A/T: the ratio of the effective reflector area, A to the total system noise temperature, T. The Eleven antenna was first described in [3], and the further developments are described in [4]. Other candidate feeds are the quadridge horn [5] and the quasi-self-complementary antenna [6].