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NA Cable Measurements

Question asked by SOLT_guy on Feb 9, 2011
Latest reply on Feb 20, 2011 by SOLT_guy
Dear Sir:

      I was measuring a very lossy cable and after calibration I noticed that when I inserted the cable there was a dramatic phase shift, almost 45 degrees. 

      Network analyzer literature often tells the reader to make open ended cable measurements at a specified frequency with respect to the length of the Tline.  

      When the insertion of a device after calibration causes a dramatic phase shift, to be consistent with the literature which is based upon electromagnetics physics equations, should I try to correct the phase shift errror or should I proceed with the experiment and add however many degrees (Smith Chart Angle) to the phase shift when I am instructed to make such a measurement.  

       I am measuring Zo of a cable using the equation S11=jZin=-jZo*cot(pi/4). 

       In your reply, can you please indicate whether it is best to always make the correction in the case of an inconsistency or not to make a correction and proceed with the measurement.

       In Agilent's experience with this issue, what course of acton has its engineer taken.  

       Thank you for your replies.  

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