We use a model E8364A and are not quite sure what the uncertainties of our measurements are. We are collecting data from check standard measurements for the random component, but have no idea what the systematic errors are.

I have seen (but not used yet) the VNA Uncertainty Calculator available for download. I was somewhat concerned about the big warranty warnings however. Is the warning to say that the results are not reliable?

I have also seen in this forum the poll asking if more uncertainty data is needed. Obviously I said yes.

I hope someone can shed some light on this matter.

Thanks,

Will Rogers

Metrologist

LMTO

I have seen (but not used yet) the VNA Uncertainty Calculator available for download. I was somewhat concerned about the big warranty warnings however. Is the warning to say that the results are not reliable?

I have also seen in this forum the poll asking if more uncertainty data is needed. Obviously I said yes.

I hope someone can shed some light on this matter.

Thanks,

Will Rogers

Metrologist

LMTO

If I may rephrase your question, I think what you are asking about regarding the VNA Uncertainty Calculator accuracy is how many sigma is associated with the VNA uncertainty calculator, i.e., its measurement confidence probibility in terms of +/- X sigma.

According to the Agilent R&D Engineer (who originally developed this VNA Uncertainty spreadsheet calculator), each of the individual residual systematic error terms (as documented in the analyzers technical specifications) have a +/- 2 sigma (i.e. 95% confidence probability). However, in the case of the VNA Uncertainty Calculator these terms are added or combined together which results in a worst-case value for the total systematic error. (as an example see attached taken from the 8720/22ES ref. guide, Ch 10,

http://cp.literature.agilent.com/litweb ... -90393.pdf

"Determining (VNA) System Measurement Uncertainties", ppgs 10-8 through 10-10).

However for the VNA Uncertainty Calculator, this worst-case total systematic error, would have a confidence probability approaching +/-3 sigma.