Bilateral comparison of 1.85 mm coaxial air line dimensional and characteristic impedance measurements between NPL and NMIJ

This paper summaries a bilateral comparison of measurement of the diameters of two precision 1.85 mm coaxial air lines. These dimensional measurements were made independently by two national metrology institutes: NMIJ and NPL. The laboratories also calculated the characteristic impedances and their uncertainties based on the measured diameter values and uncertainties. The difference between the characteristic impedances calculated by the two laboratories for both lines was less than 0.2 Ω The uncertainty of this difference at a 95 % level of confidence was 0.3 Ω.