VNA Noise on ZVRE after update to V2.5

[cbac...@emc-testcenter.com]

Hi Michael,
since I updated to VNA Tools V2.5 the MU is not evaluated correctly anymore. Seems I'm missing the value for (VNA Noise - Floor - S-Parameter), see plot. It seems the problem only occurs on R&S ZVRE but not on R&S ZNB. What do I need to do, to add this value? Measurements from before the update show the complete MU.

Thanks and regards
Cecile

[Guillermo Monasterios]

Hi Cecile,

Let me give you a comment about it. Please, try the following:

1)      Edit the Journal_01.vnalog file of your project with a text editor.

2)      Locate the <PortSlope> tags. There should be two of them with a “NaN” value.

3)      Change both NaN values to 0.

4)      Save your file and calibrate and error-correct your measurements again.

Hope this helps.

Regards,

Guillermo

[cbac...@emc-testcenter.com]

Hi Guillermo,
thanks this works for now, but I have a lot of these <PortSlope>  tags, I had a long journal and changed the settings several times, so I had to correct them all.
So, for the future I would prefer a solutions how it comes correct from the beginning, instead of correcting them all in the end.

I checked the "VNA settings" and found the following problems when using the "Segment sweep". When I recall a saved Instrument State I can take one with "Sweep Mode" LogFrequency or LinearFrequency and the PortSlope will be set correctly to 0. I can now change the Sweep Mode to SegmentSweep and I can load a frequency tabe which I have saved before (or I can make a new one, the effect is the same). And now I save the new VNA Settings, but it will not save the settings I set before. To see this I made two plots one before saving and one after recalling the settings. As it can be seen neither the frequency table nor the PortSlope is saved correctly. Also when I just hit VNA Settings again after performing some measurements in the same journal, because I want to change the settings. I will see the same frequency table but the PortSlope is automatically set to NaN. Unfortunately I did not find a way to change the PortSlope in the VNA Settings.

I also tried using other Sweep Modes than the Segment Sweep, there the problem does not occur. Actually when I'm using LogFrequency or LinearFrequency after using the SegmentSweep in the same Journal, the PortSlope will first be set to NaN because this is the case when using the SegmentSweep. But when recalling the VNA Settings the PortSlope is automatically set to 0 in those two case. So it seems they behave contrawise.

Is there a solution to fix this?

Thanks and regards

Cecile

[Michael Wollensack METAS]

Hi Cecile,

I fixed a bug in HP8751A and Rohde_Schwarz_ZVC_M_R drivers (Source1PowerSlope property changed from NaN to 0). The power slope is used to compute the noise floor uncertainty and can't be NaN.

This will be part of the next VNA Tools release V2.5.3 (beginning of march 2022).

Thanks and regards

Michael