CASS engineer Alex Dunning, testing receiver components. Photo: Tim Wheeler

Creating world-class receivers: ‘hearing-aids’ for telescopes

'Receivers' are the hearing aids of a radio telescope, boosting cosmic signals by up to a million times and CSIRO's Australia Telescope National Facility tailor-makes receivers for its own telescopes and for others around the world.

• 6 August 2007 | Updated 29 April 2013

• How CSIRO uses it
• Who else is involved

CSIRO’s Australia Telescope National Facility (ATNF) designs and builds world-class radio-frequency receivers for its own radio telescopes and those of international partner institutions and customers.

Receivers are a crucial component of radio telescopes. They amplify the weak radio signals from objects in space a million-fold.

The ATNF builds receivers that are cryogenically cooled to just a few tens of degrees above absolute zero (-273 °C). This cooling reduces the ‘noise’ present in all electrical circuits, which can swamp the delicate signals from space. The receivers are also housed in an evacuated chamber.

Each receiver is custom-designed for the telescope it is to be mounted on, and for the science goals it is to tackle.

Radio signals from space are far weaker than those used in telecommunications. Because of this, the demands on radio telescope technology are much more stringent. Radio astronomy requires systems with broader bandwidths, lower noise, and high stability.

Receivers were formerly constructed of discrete components. The ATNF is now using its own custom-designed integrated circuits, sometimes called chips, for components such as low-noise amplifiers, mixers and frequency multipliers. These components operate in the microwave and millimetre-wave range of the electromagnetic spectrum, at frequencies up to 115 GHz.

To design, construct and test receivers and their associated cryogenic refrigerators, the ATNF possesses:

• systems for measuring low (cryogenic) temperatures and vacuum pressures
• software for designing integrated circuits
• facilities for wire-bonding and packaging chips into larger sub-assemblies
• automated equipment for testing components such as amplifiers.

The ATNF’s specific areas of expertise include:

• electromagnetic design of components operating at high radio frequencies (microwave- and millimetre-wavelengths)
• fabrication of components to extremely high tolerances
• design of high-frequency indium-phosphide integrated circuits
• measurement of the performance of integrated circuits at cryogenic temperatures
• measurement of vacuum pressures
• understanding of the properties of materials at cryogenic temperatures
• understanding of the properties of surface coatings, specialised alloys, and gases used in cryogenic systems
• welding of stainless steel for vacuum chambers.

How CSIRO uses it

CSIRO builds receivers for its own radio telescopes (collectively known as the Australia Telescope):

• the six 22-metre antennas of the Australia Telescope Compact Array near Narrabri, NSW
• the 64-metre Parkes radio telescope near Parkes, NSW
• the 22-metre Mopra telescope near Coonabarabran, NSW.

Who else is involved

CSIRO builds receiver systems for telescopes of other institutions, such as Cornell University’s Arecibo radio telescope in Puerto Rico and the University of Manchester’s Jodrell Bank Observatory in the United Kingdom.

CSIRO has also built receiver systems for NASA for use on the Parkes telescope, to allow Parkes to track specific spacecraft, for instance, the Galileo spacecraft at Jupiter in the 1990s and spacecraft around Mars in 2003-04.

Learn more about Radio Astronomy.