  An analytical method was developed, to estimate uncertainties in full
two-port Vector Network Analyzer measurements, using total differentials of
S-parameters. System error uncertainties were also estimated from total
differentials involving two triples of standards, in the Direct Through
connection case. Standard load uncertainties and measurement inaccuracies were
represented by independent differentials. Complex uncertainty in any quantity,
differentiably dependent on S-parameters, is estimated by the corresponding
Differential Error Region. Real uncertainties, rectangular and polar, are
estimated by the orthogonal parallelogram and annular sector circumscribed
about the Differential Error Region, respectively. From the user's point of
view, manufactures' data may be used to set the independent differentials and
apply the method. Demonstration results include: (1) System error differentials
for Short, matching Load and Open pairs of opposite sex standards; (2) System
error uncertainties for VNA extended by two lengthy transmission lines of
opposite sex end-connectors; (3) High uncertainties in Z-parameters against
frequency of an appropriately designed, DC resistive, T-Network; (4) Moderate
uncertainties in amplitude and phase patterns of a designed UHF radial discone
antenna (azimuthally rotated by a built positioner, under developed software
control of a built hardware controller) polarization coupled with a constructed
gain standard antenna (stationary) into an anechoic chamber.
