How do I characterize a Connector?

[roschiroh...@gmail.com]

Hi,

How do I characterize a Connector?

- Repeatability (dB)?

So far we have followed this procedure:

1. Calibrate VNA with VNA Tools II.

2. Connect a Short to the Connector.

3. Measure S1;1.

4. Turn the Short approx. 45°.

5. Repeat the steps 3 and 4 seven Times (8 Measurements -> 360°)

6. Normalize to Mean.

7. Repeatability (dB) = 20*log(max. Deviation Mag lin)

We have followed this procedure with a Short and a Load (Step 2). However, we got major differences between those two results (Load is much better than the Short).

Thank you.

Regards

Christoph

[Tuomas Haitto]

Hello Christoph

Maybe METAS fellows has better answers, but if you want characterize your test port adatpers. Use very repetatable short component and measure it on different connector orintations as you have done.

Now must remember, that short component's repeatability characteristics must be better than your connector what you testing. If not so, you can't find out does errors comes from testport connector or from your short.

- Tuomas

  

[roschiroh...@gmail.com]

Hi Tuomas

Thanks for your answer.

Both the short and load were calibrated by Metas this year, therefore the repeatability should be fine for both. However, we don't know the value of repeatability of the short or load.

Can you explain us, why you should use a short and not an open or a load for this characterization?

Christoph

[Tuomas Haitto]

Hi,

Okey, if they are tested in METAS without any notes then you have good standards !! Short is better to use , because then you can find out possible phase errors between each positions.

Using load it's not practically possible. Short also returns back to VNA bigger energy and that way possible erros is better to detect. If your load and tesport reflection coeffients are

very good, then possible errors are hard to find. Short just reveals errors better than load )) Because you looking for only differences between each positions you can do analyzing

with RAW data only. That is even better and tells more directly true performances of the connector repeatability. I always do such a data comparisons with error corrected and RAW data sides.

- Tuomas    

[Cecile Bachmann]

Hi,

I have the same question.

I measured a short at 16 different positions, to evaluate the connector repeatability.

How do I now evaluate my data, to get the Reflection repeatability and the Transmission Repeatability which should be entered in VNA Tools?

Thanks and regards

Cecile

[Michael Wollensack METAS]

Hi Cecile,

see https://www.euramet.org/Media/news/I-CAL-GUI-012_Calibration_Guide_No._12.web.pdf Appendix G.5 Connector repeatability. 

By the way the guide is not including a transmission repeatability term. So you can assume it as zero. The transmission repeatability term was added to VNA Tools to have connectors with a larger phase variation than magnitude variation, e.g.: snap on connectors.

Regards

Michael

[Fabian Distler]

Hello,

When characterising a test port adapter, does it make a difference whether one calibrates before the connector or after the connector?

Regards 

Fabian