An analysis is presented of the generalized weighted mean of a set of quantities, some or all of which may be correlated, and the variance associated with that mean. The cases covered specifically are (a) two correlated quantities, (b) a general number of quantities, two of which are correlated and (c) a general number of quantities, all of which are correlated. For (c), two instances are treated, namely where the quantity variances are equal and unequal. Consistency of the data representing realizations of the quantities concerned is shown to be important in terms of appreciating the results obtained.

A measurement comparison of noise temperature has been carried out between four National Metrology Laboratories in coaxial line at 30 MHz, 60 MHz and 1 GHz. The identification of this intercomparison is CCEM.RF-K18.CL. Two noise sources have been measured. The following four national laboratories participated in this intercomparison: NPL (United Kingdom), NIST (United States of America), BNM-LNE (France) and VNIIFTRI (Russia). The National Physical Laboratory (United Kingdom) acted as the pilot laboratory for the comparison. It can be seen that, there is generally good agreement between the laboratories.

No abstract

Beadless coaxial air dielectric transmission lines can be used as fundamental reference devices for S-parameter measurements at RF and microwave frequencies. However, for these lines to be used for such applications, they must first be characterised accurately in terms of their impedance and propagation characteristics. This includes assessment of the small amount of loss in the line and the associated impact of this loss on other characteristics. A simple method is presented whereby the loss is determined experimentally using a vector network analyser (VNA). The determined loss can then be used to characterise the line so that it can be used for a range of highprecision metrology applications. Two such applications are given: determination of the actual frequency-dependent characteristic impedance of a line; and use of the line's phase constant to verify VNA phase measurements.

The CCEM international antenna gain comparison CCEM.RF- K23.F was initiated by the Working Group on Radio Frequency quantities (GT_RF) on the Consultative Committee for Electricity and Magnetism. This key comparison report presents results of measurements of on-axis gain of two Ku-band pyramidal horns at 12.4, 15, and 18 GHz. Participants making corrections for mismatch were asked to provide a table of the real and imaginary parts of the reflection coefficients of the antennas. Optionally, participants could measure the swept frequency gain from 12.4 to 18 GHz. Twelve national laboratories participated. The National Institute of Standards and Technology from the United States was the pilot lab. The purpose of the comparison was to evaluate the consistency between the participating laboratories in the measurement of the boresight gain of horn antennas in the WR-62 band. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).