International Comparison of Voltage (1 V) in Coaxial Line at Frequencies up to 1 GHz

Abstract

This report deals with a comparison of national standards of rf voltage organized by the radiofrequency working group of the "ComitC Consultatif d'ElectricitC" of the .Bureau International des Poids et Mesures (BIPM). It was done by sending round transfer standards, for each of which the participating laboratories had to measure the rf-dc difference for a reading of 1 V at frequencies from 100 MHz to 1 GHz. The seven standardizing laboratories participating in this comparison were: ASMW (GDR), EQD (United Kingdom), NBS (USA), NML (Australia), OMH (Hungary), PTB (FRG) and VNIIM (USSR). The Physikalisch-Technische Bundesanstalt (PTB) acted as pilot laboratory. Two kinds of transfer standards were circulated in two separate cycles: two resistance mounts (50 S-2 and 75 S-2 input impedance) and two thermal converters made available by the PTB and the OMH. The results are presented in two tables and 16 bar charts. A weighted mean value for each transfer standard and frequency was calculated from the measurement results. Good agreement between the measurement values of all participants was achieved. For resistance-mount transfer standards the deviations of the measured values from the weighted mean values were 5 4 x lop3 for all frequencies up to 1 GHz, for thermal converters all deviations were 5 3 x lop3 at 100 MHz and 5 1.2 X lop2 at 1 GHz (excluding one measurement point). All the transfer standards remained sufficiently stable over a measuring period of more than 5 years.

Evaluation of a Calorimetric Thermal Voltage Converter for RF–DC Difference up to 1 GHz

“…In the frequency band 100 MHz to 1 GHz, the characterizations of the TVC RF-DC transfer difference are carried out either in terms of the power and impedance using thermistor mounts [13], [14], or in terms of the effective efficiency of a thermistor mount and the RF and DC conductances at its input connector [15].…”

“…For this reason, besides using the well-established calibration method based on a thermistor mount [13]- [15], we decided to characterize the CTVC RF-DC difference in terms of the voltage reflection coefficient (a parameter which can indicate the degree of impedance mismatch) at the input of a thermistor mount. In the following, the proposed method is described in detail.…”

Improving the primary power standard below 10 MHz with thermoelectric sensors

“…They have the same structure of the TVCs used for voltage standard comparison in coaxial lines, [9]. Therefore they can be calibrated against other standard TVCs, by comparison on an unmatched T-junction, in terms of transfer difference δ, defined as:…”