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VNA Measurement Uncertainty

Question asked by chard on Dec 22, 2010
Latest reply on Feb 15, 2011 by Dr_joel

I downloaded the VNA uncertainty measurement calculator at and am now trying to figure out how to correctly apply it. In my specific case, I have a two port circuit that was measured on an E5071B VNA using the 85033E cal kit. I figured out how to enter this information into the calculator spreadsheet.  However, I'm not sure about how to apply it to my measurements.

I assume I go to the curves and extract the specific  S11m,S11p,S21m,S21p uncertainty.  Now, how do I apply these data to my  (E5071B) measurements?  Do I add these uncertainties to my specific measurements. For example, if my actual S11 magnitude measurement is S11ma (magnitude actual) and the uncertainty is S11mu (magnitude uncertainty), is my measurement uncertainty equal to S11ma +/- S11mu?  Same thing for phase uncertainty and the transmission coefficient? 

I also want to calculate the dissipative loss of the highly reflective (into 50-ohms) 2-port by using the formula Loss=|S21|^2 / ( 1 - |S11|^2) .  Will the uncertainty analysis provide a useful estimate for loss?  Is there any correlation between the S11 and S21 uncertainty?