International comparison GT-RF/83-4: measurements of scattering coefficients over the band 2-18GHz.

This is a detailed report of a international comparison of one of the most important microwave parameters, namely impedance. The comparison was actually of one of th,e manifestations of impedance called scattering coefficients and was given the title "Measurements of scattering coefficients over the band 2 -18 GHz" and the reference number GT-RF/83-4 by the relevant CCE working group. The following institutes participated: PTT (Switzerland), VSL (the Netherlands), NIST (United States of America), FFV (Sweden), LCIE (France), IEN (Italy), PTB (Germany), CSIRO (Australia) and NPL (United Kingdom), the latter as pilot laboratory. The items to be compared were all fitted with precision GPC- 7 sexless 50 ohm coaxial 7 mm connectors so that they were both reversible and insertable. Six items, consisting of four two-port devices and two one-port devices, were circulated to the participants who were asked to supply measurements of the scattering coefficients (referred to 50 ohms) of each of the items at 65 frequencies, covering the range 2 to 18 GHz in steps of 0.25 GHz. Because of the vast amount of data generated, traditional methods of evaluating the comparison were not necessarily appropriate and this report explores some of those issues as well as presenting a election of the results. It is intended that material drawn from this report will be submitted to BIPM for publication as the final report.