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PNA-X - FW A10.49.03. Wrong K-factor calculation with port extention

Question asked by mirek on Mar 3, 2016
Latest reply on Mar 7, 2016 by mirek
I think that I found bug in K-factor calculation when port extension is apply.
We have a problem with one of the amp stability so I measure S-parameter with one of our in house test program that calculate K-factor. So I see serious issue at at around 16GHz.
I then add the trace to my PNA-X S-parameters and enable the K-factor formula so I can do some DUT tuning. I was bit surprised but that DUT did not show such big dip at 16GHz with PNA-X formula. I first suspect our test program have bug. I remeasure the DUT without port extension enable on PNA-X with our test program. Both PNA-X and our test program showing similar reading.   
Something do not add up.
I generate s2p files. One when the port extension is enable and one when is disabled. 
I then plug the data into S-Parameter_Utilities_101_Rev_6.3 ( that excel file utility from Microwave101 web side) .
I get similar difference in results.  

Can you please check that. K-Factor is important characteristic.
See the attach file