Superconducting filters for radio astronomy

Superconducting filters provide extremely low loss and very sharp transitions from stop bands to pass bands and are therefore ideal for cutting out interference in a radio astronomy receiver. The collaborative work between the Jodrell Bank Observatory operated by the University of Manchester and the University of Birmingham has produced a range of filters operating in a number of observation bands between around 400 MHz and 8 GHz. Some of these filters have been tested in receivers and used for astronomy. This paper discusses the design of HTS filters, the mounting of the filters into a cooled receiver and the improved results obtained in astronomical observations. In addition, such a filter has been designed to operate in each element in a focal plane array, in this case a large number of filters are required in the array and miniaturization is a crucial criteria