Radio telescope receivers for ALMA

Daniels Electronics has successfully completed a $1.3 million contract with the Canadian government for the assembly and test of radio receivers used in the National Research Council of Canada (NRC) development of 84-116 GHz heterodyne receivers for the international Atacama Large Millimeter Array (ALMA) telescopes.

ALMA is located at 5000 m elevation in the Chajnantor Plain of northern Chile. The resolution and sensitivity of the array will provide a leap forward, making it a pre-eminent radioastronomy facility.

NRC’s contribution to the project included 73 extremely sensitive 84-116 GHz receivers. The nucleus of the receiver is a superconductor-insulator-superconductor (SIS) tunnel mixer which downconverts the RF signal collected by the radio telescope to an intermediate frequency (IF) signal centred at 6 GHz with a bandwidth of 4 GHz.

A cryogenic high electron mobility transistor (HEMT) amplifier is used to amplify the IF signal by more than 30 dB before it is delivered to the ALMA back-end system. The SIS detector and the HEMT IF amplifier must operate at a cryogenic temperature of 4 Kelvin. NRC has developed a cryogenic 4-8 GHz HEMT amplifier for this application.