Calibration of a precision three-port coaxial junction: a new component for immittance standardisation

In a number of earlier papers, the general theory of a three-port coaxial junction was given together with applications in immittance standardisation, the generation of reflection coefficient standards inside the unit circle and S21 standards less than unity by reflective attenuation. Since then, a precision three-port junction has been constructed for use with 14.2875 mm precision connectors. Many calibration techniques have been investigated. The results of two of these are given in detail. The first at 1.1243 GHz and the second at 10 kHz give port lengths that agree to within 0.1 mm, which indicates that the electric field configuration at the junction is substantially the same at the two frequencies. The higher-frequency technique also gives the attenuation of the junction arms, which was found to be close to the theoretical value. Two other techniques of somewhat lower accuracy are described.