Development of a coolable 2–14 GHz Eleven feed for future radio telescopes for SKA and VLBI 2010

The Eleven feed is a log-periodic array of parallel dipoles in Eleven (II) configuration. It exhibits constant beam width and phase center position over a decade bandwidth, and finds therefore application as a wideband feed for reflector antennas. The present paper gives a summary of the present performance of a 2-14 GHz Eleven feed that is under development for use as a feed for VLBI 2010 radio telescopes for geodesy. Previous reported Eleven feeds did not reach that high in frequency. The intention is also to develop a feed that can be integrated with a low noise amplifier inside a cryostat at temperature of 14 K, and receive the waves focused by the primary reflector through an RF window in the cryostatic cavity. Thereby the lowest system noise temperature is ensured. The present model has successfully survived cooling to 14 K.