Sorry I forgot to mention it. I did calibrate it. And also tried with a
second nanoVNA. In both cases I got the weird impedance values.
So far I've been using the vna to measure HF antennas with no problems. The
results always matched other swr meters, for example.
El mi¨¦., 19 feb. 2020 08:40, Reinier Gerritsen <r.gerritsen@...>
±ð²õ³¦°ù¾±²ú¾±¨®:
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Check you calibration
Op 19-2-2020 om 12:12 schreef Hern¨¢n Freschi:
I recently tried to measure input impedance on a helical filter. the
problem is, the plot went outside the smith chart, and the marker showed
negative impedance values and other crazy stuff.
what could be the cause for this?
the filter was only 137mhz so it should be well within the range of the
VNA. the expected impedance is 50 ohms. the filter passband was measured
correctly, and the return loss showed a sane value. only the smith chart
was empty.
thanks.
