Pattern Measurements of Cryogenically Cooled Ultra-Wideband Feed Horn

Thermal changes can have an effect not only on the dimensional stability of mechanical parts but also on their dielectric properties as well as the phase and amplitude of active components. An ultra-wide-bandwidth receiver has been developed for the Parkes Radio Telescope. Radiation patterns of the feed were measured at cryogenic temperatures in the CASS anechoic chamber at Marsfield. The internal features of the final design were adjusted to account for dimensional changes of the materials at cryogenic temperatures.