AnsweredAssumed Answered

AFR is being stupid !

Question asked by mikejvir- on Dec 7, 2018
Latest reply on Dec 13, 2018 by bobls

Hello All,


Please accept this note as a rant and I am bloody PO.  I am using AFR on the PXI network analyzer.  AFR works great but has a major, major flaw (Keysight will call it a feature). 

We have AFR only on one VNA.  This was done because besides measuring data AFR can also read s-parameter files.  So we take data on a 50 GHz VNA  save the S-parameter file (filename.S2P) and generate the modelsfor the two ports.  Been working great for 1 year.


Well today I get this error.

Error Message


A S2P has no port identifier though the order is S11. S21, S12, S22 in the generic sense.  I did track this down to the following.  Inside the file Keysight adds comments when storing the file off the VNA and here is what was in it.


!Date: Thursday, December 06, 2018 20:02:24

!Correction: S33(Full 2 Port(3,4))

!S43(Full 2 Port(3,4))

!S34(Full 2 Port(3,4))

!S44(Full 2 Port(3,4))

!S2P File: Measurements: S33, S43, S34, S44:

# Hz S  dB   R 50


Bloody hell.  Since when does adding comments to  SxP files DICTATE how the file is used? And no this are not Version 2 SxP files and yes I have been around since EEsof first generated this file format in the early 1980's


Needless to say once I changed all the files to say port 1 and 2 (via text editor)  like


!Correction: S11(Full 2 Port(1,2))

!S21(Full 2 Port(1,2))

!S12(Full 2 Port(1,2))

!S22(Full 2 Port(1,2))

!S2P File: Measurements: S11, S21, S12, S22:

# Hz S  dB   R 50


everything worked as it should be.




Thanks for letting me rant.



Michael J. Virostko
Principal Product Application Engineer

+1 978.577.6347 direct