Practical evaluation of phase uncertainty in scattering parameter measurements

This paper reports an evaluation of phase uncertainty in scattering parameter (S-parameter) measurements. Methods of Law of Propagation of Uncertainty and Coordinate Rotation have been used to transform uncertainty information of the real and imaginary components in a complex-valued S-parameter to its phase. Practical evaluations with measurements were carried out to check the consistency between the two methods. Good agreements have been observed except for the situation where the uncertainty region encompasses the origin of a rectangular coordinate.