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Successful international measurement comparison for radio frequency power at 50 GHz to 75 GHz


Foto des Transfernormals PTB-1

To support the metrological equivalence of national measurement standards in the framework of the CIPM Mutual Recognition Arrangement (MRA), a key comparison in radio frequency (RF) power in rectangular waveguide was agreed in 2015 and has been performed between May 2019 and December 2021. The key comparison with the designation CCEM.RF-K27.W had eight participants, was coordinated by NIM (China) with support from NPL (United Kingdom) and PTB (Germany). Excellent agreement among the participants was achieved.


The International Committee for Weights and Measures (fr. Comité International des Poids et Mesures), CIPM, has the principal task to promote world-wide uniformity in units of measurement within the MRA. In the key comparison CCEM.RF-K27.W, the effective efficiency and the calibration factor of two traveling standards provided by PTB were determined by eight participating National Metrology Institutions.


The traveling standards were waveguide thermistor RF power sensors with interfaces of type WR 15 (R 620). Five institutes directly determined the effective efficiency by microcalorimeter measurements. Three participants applied second-order calibration methods (e.g., direct comparisons), two of them using their own microcalorimeter-calibrated transfer standards, and one using a calorimeter as reference standard.


The results were evaluated at the frequency points 50 GHz, 55 GHz, 60 GHz, 65 GHz, 70 GHz, and 75 GHz by determining the key comparison reference values (KCRV) for both the effective efficiency and the calibration factor. The reported results were related to the KCRV by calculating the Degrees of Equivalence (DoE) and their expanded uncertainties. PTB achieved very good agreement with the KCRV for the complete frequency range and thus confirmed its Calibrated Measurement Capabilities (CMC) for RF power.


Figure: Photographs of the travelling standard PTB-1.


Contact person:

Karsten Kuhlmann

Department 2.2 „High Frequency and Electromagnetic Fields"



Head of Press and Information Office

Dr. Dr. Jens Simon

Phone: +49 531 592-3005


Physikalisch-Technische Bundesanstalt
Bundesallee 100
38116 Braunschweig