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Hello,

v0.7.3 on Windows;

Already had my nanovna calibrated in two range: 30 MHz around 315 and another 30 MHz around 434; used an average of 10 sweeps with ~saver which has produced some partly negative values for resistance - measured two (almost) identical antennas, without any in- ~saver calibration. I can say for sure that nanoVNA did not report any negative resistances.

Having seen the failure, i have then set an interval from ~225MHz to 525MHz, some ~300 points, calibrated inside ~saver, remeasured the two antennas with generally different results, but still having ranges of frequency where the resistance was again negative. I have not properly checked what the naonoVNA was reporting on its screen for the frequency range.

What am i doing wrong ?

Thanks!

What am i doing wrong ?

** I think it would have been relevant, since you use nanaovna-saver, to post your .s1p files with your participation.
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F1AMM
Fran?ois

-----Message d'origine-----

De la part de kellogs

Envoyé : vendredi 28 mars 2025 21:30

You might be receiving strong signals with that antenna, that interfere with the nanoVNA's measurements. If that's the case, at least some of the excursions to negative resistance should not repeat on every scan.

If that's not the problem, it might be just noise.

Have you tried reducing the sweep range? It might be informative to reduce the sweep to 25MHz starting at 300MHz, OSL calibrate at the measurement plane and run the sweep. Then move up 25MHz and run again. This will help focus down on where the issue is. Instinctively, I agree with Manfred, but there may be some oddity creeping in from the nano internals on such a wide sweep.

Steve
G0AIN