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The 30/60 MHz Tuned Radiometer - The NIST System for Noise Temperature Measurements



Chriss A. Grosvenor, Robert L. Billinger


The NIST Noise Project has completed reconstruction of their 30/60 MHz tuned, coaxial (Type N) radiometer system. This system is used at low frequencies where isolators are impractical to incorporate. Without isolators, the ambient and cryogenic standards are tuned to the impedance of the device under test to minimize mismatches. Although this system had been in existence prior to this technical note, enough modifications and improvements have been made to warrant a new discussion. This note will briefly review the original system, discuss the theory as well as the design, testing, and capabilities of the present system. A more detailed uncertainty analysis is included and an appendix for troubleshooting the system.
Technical Note (NIST TN) - 1525
Report Number


noise, noise measurement, noise temperature, radiometer, thermal noise


Grosvenor, C. and Billinger, R. (2002), The 30/60 MHz Tuned Radiometer - The NIST System for Noise Temperature Measurements, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD (Accessed June 25, 2024)


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Created April 30, 2002, Updated October 12, 2021