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Experimental Astronomy

, Volume 33, Issue 1, pp 225–236 | Cite as

Superconducting filter for radio astronomy using interdigitated, capacitively loaded spirals

  • Pietro Bolli
  • Frederick Huang
Original Article

Abstract

A matched pair of microstrip spiral superconducting filters with centre frequency 357.5 MHz and 29.4% bandwidth has been developed for radio astronomy. The high coupling coefficients required for the large bandwidth have been achieved through interdigitating the spirals to provide a large interaction length, and by adding loading capacitors on the inner ends of the resonators, together with previously reported features. A low-pass filter has been cascaded with each band-pass filter to mitigate spurious responses. Measurements show 0.09 dB loss, thought to arise mainly from sources outside the filter itself, plus 0.12 dB maximum ripple.

Keywords

Astronomy receiver design Computer-aided design High-Tc superconducting thin-film filters Microwave filters 

Notes

Acknowledgements

The authors acknowledge the help of Prof. Michael Lancaster of the University of Birmingham and Dr. Alessandro Navarrini of the INAF—Osservatorio Astronomico di Cagliari for making this research project possible.

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Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  1. 1.Astronomical Observatory of CagliariNational Institute for AstrophysicsCapoterraItaly
  2. 2.School of EECEUniversity of BirminghamEdgbastonUK

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