A Tri-Band Cooled Receiver for Geodetic VLBI

Area of Science:

• Radio astronomy
• Geodesy
• Cryogenic engineering

Background:

• Geodetic Very Long Baseline Interferometry (geo-VLBI) is crucial for precise Earth observation.
• Existing receivers face limitations in noise reduction for optimal performance.
• The VLBI Global Observing System (VGOS) requires advanced instrumentation for high-accuracy measurements.

Purpose of the Study:

• To develop and demonstrate a simultaneous tri-band (S, X, and Ka) low-noise cryogenic receiver for geo-VLBI.
• To minimize receiver noise by enabling full front-end cooling to cryogenic temperatures.
• To validate the receiver's performance in operational geodetic networks.

Main Methods:

• Design and fabrication of a fully coolable cryogenic receiver covering S-band (2.2-2.7 GHz), X-band (7.5-9 GHz), and Ka-band (28-33 GHz).
• Integration and testing of the receiver in a VGOS radio telescope at Yebes Observatory, Spain.
• Deployment and performance evaluation in international VGOS stations, including Norway and Portugal.

Main Results:

• Achieved average receiver noise temperatures of 21 K (S-band), 23 K (X-band), and 25 K (Ka-band).
• Measured antenna efficiencies of 70% (S-band), 75% (X-band), and 60% (Ka-band).
• Successful deployment and operation in multiple VGOS stations, confirming reliability and performance.

Conclusions:

• The developed cryogenic receiver significantly reduces noise, enhancing geo-VLBI capabilities.
• The fully coolable front-end design represents a technological advancement for radio astronomy receivers.
• The receiver's successful implementation in global networks contributes to improved geodetic measurements and Earth observation.