Author Topic: VNA One Port Fixture De-Embedding Experiment  (Read 1805 times)

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Offline rf-messkopf

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Re: VNA One Port Fixture De-Embedding Experiment
« Reply #25 on: May 18, 2021, 03:56:35 pm »
Yep. It completely zeros out the fixture, almost like I'm taking a "delta" measurement. That's basically what I figured I'd do in my original post. Also, what do you mean by "up to an overall phase"?

If I'm not mistaken, when you do trace normalization with a short i.e., do the \$S_{11}^{\text{meas}}/S_{11}^{\text{ref}}\$, you get an extra phase factor of \$\exp(\mathord{\rm i}\pi)=-1\$. When you do the same with an open, your extra phase factor is just \$\exp(\mathord{-\rm i}0)=+1\$. The "Direct Compensation" function should take care of that automatically. If you use trace math instead, you'll have to compensate for the \$-1\$ manually.

Edit: Corrected the math. The statement should be ok now.
« Last Edit: May 18, 2021, 04:26:45 pm by rf-messkopf »
 
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Offline Joel_Dunsmore

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Re: VNA One Port Fixture De-Embedding Experiment
« Reply #26 on: May 18, 2021, 06:58:08 pm »
R&S ZNL has auto port extension (estimate the phase delay and loss) built-in.
Yeah, they added it after we did.  I like my implementation better, fitting is better I think.

It also has the provisions of defining a custom cal kit at no added cost required, something I know that you have to pay for with Keysight VNA's (I know because the mmWave guys next door keep complaining about it).
  As far as I know, you can create whatever cal kits you want just by creating a new one. There is a paid-for version of a wizard in the PLTS that does quite complicated things, but for normal cal kits I think the free version is available. I just downloaded on my home PC and it seems to not require any license.  I got it here: http://na.support.keysight.com/pna/apps/#calkiteditor
Of course this makes calkits that are compatible with Keysight VNAs, maybe you have to change the units to Euros or something to run on other products.
the same page has a bunch of little helper code.
 
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Offline Andrey_irk

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Re: VNA One Port Fixture De-Embedding Experiment
« Reply #27 on: September 14, 2021, 01:31:42 am »
R&S ZNL has auto port extension (estimate the phase delay and loss) built-in.
Yeah, they added it after we did.  I like my implementation better, fitting is better I think.

It also has the provisions of defining a custom cal kit at no added cost required, something I know that you have to pay for with Keysight VNA's (I know because the mmWave guys next door keep complaining about it).
  As far as I know, you can create whatever cal kits you want just by creating a new one. There is a paid-for version of a wizard in the PLTS that does quite complicated things, but for normal cal kits I think the free version is available. I just downloaded on my home PC and it seems to not require any license.  I got it here: http://na.support.keysight.com/pna/apps/#calkiteditor
Of course this makes calkits that are compatible with Keysight VNAs, maybe you have to change the units to Euros or something to run on other products.
the same page has a bunch of little helper code.


My employer has a 20GHz E5071C of some later revision. It doesn't have an option (neither does the calkiteditor you mentioned) to create a cal kit with s-parameter characterized standards. As I understand, it means there is no way you can get the maximum accuracy out of the mechanical SOLT cal kits. Annoying.
Of course, you can say you get what you pay for, but there are free tools like METAS VNA Tools that allow using your uncorrected VNA data along with measured standards data to do correction on your PC.
Also, that E5071C has a deembedding feature, but no way you can rotate the S2P file!
Other than that I like Keysight VNAs. The interface is the best in my opinion, the performance is solid. Great stuff.

P.S. I'm glad to see you here and thanks for the book you wrote, I love it!
 


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