VNA Tools 2.5: Power Sensor Measurement

[Fabian Distler]

Hello to all,

 

I have a question regarding the new feature in VNA Tools 2.5: Power Sensor Measurement.

I have tested the new feature with a power sensor and a NRVD readout device.

The VNA's power is set to - 10 dBm.

The result of the power sensor measurement looks plausible, except for the graph of the VNA test port power.

The graph shows a power of about -23 dBm, but shouldn't this also show about - 10 dBm power?

 

Attached is the plot of my measurement.

Also the error correction seems to have no influence on test port power.

Has anyone had experience with the new function or know how to interpret the measurement result?

Thanks a lot!

[Michael Wollensack METAS]

Hi,

I guess you have an R&S ZNA VNA.

VNA Tools reads out the raw wave and S-parameters. So it turns off the factory calibration.

You can do that as well on the VNA, see Wave Correction.

https://www.rohde-schwarz.com/webhelp/ZNA_HTML_UserManual_en/Content/5e682cb14ab74a5b.htm?Highlight=Wave%20Correction

Then you will see the same raw wave parameter values on the VNA and in VNA Tools.

So on the ZNA this offset is about -13 dB. Using a Keysight PNA this offset is about 0 dB.

At the end this offset doesn't matter. It will be part of your calibration error terms.

Hope this helps.

Regards

Michael

[Fabian Distler]

Hello Michael,

Thanks for the information.

We were using a Rohde & Schwarz ZVA40 VNA for the performed measurements.

I understand your point but the problem is that there is no significant error correction happening.

I have attached the uncorrected measurements, the  uncorrected measurements, the diffrence between the two and the calibration error terms.

Regards

Fabian

[Michael Wollensack METAS]

Hi,

you didn't performed a power calibration in your calibration config. Otherwise the S42 generic error terms would be 1 (or 0 dB). And in your error corrected data S42 should be the calibration factor of the used power sensor.

So add a line to your calibration config with the Description Power 2.

Hope this helps.

Regards

Michael

[Fabian Distler]

Hi Michael,

thanks for the info!

 I added the power calibration to my calibration config and it worked!

Somehow i thought it is possible to calibrate power sensors with the VNA as reference device (e.g. calibrated signal generator) but in order to calibrate power sensors i need a reference power sensor, right?

Thank your for your quick respond!

Regards

Fabian

[Michael Wollensack METAS]

Hi,

yes you need a reference power sensor.

Regards

Michael