Verifying transmission phase measurements at millimeter wavelengths using beadless air lines

This paper presents a simple method for verifying the phase of transmission measurements - for example, as made using instruments such as Vector Network Analyzers (VNAs). Examples are given that show the method being used at millimeter wavelengths (i.e. at frequencies up to 65 GHz) in the 1.85 mm coaxial line size. These examples use measurements made independently at the national measurement institutes of Japan and the United Kingdom. An analysis is also given showing the overall uncertainty for the method. It is hoped that the method, along with the uncertainty analysis, will be suitable for use by other laboratories seeking verified and/or accredited measurements of this type.