Determination of scattering parameters with respect to the characteristic impedance of precision coaxial air-line standards (network analysers)

Scattering parameter expressions with respect to the characteristic impedances corresponding to the principal mode are developed for the coaxial air-line standard. Dimensional variations of the inner and outer conductors and skin-effect loss are included in the model. The local characteristic impedance, which is found from the stored energy principle, is derived from the forward and backward voltage and current waves of the principal mode. Four sources of error for mod S/sub 11/ mod are discussed. Modeling accuracy for the scattering parameters and characteristic impedance is shown to be primarily dependent on conductor radius measurement precision.<>