On Sat, Feb 8, 2025 at 09:15 AM, DiSlord wrote:
NanoVNA has a port renormalization function (called Port Z, see DISPLAY->PORT
Z: 50) that allows you to see the measured S parameters at other port
impedances.
But since NanoVNA is only available for measuring S11 and S21 parameters, the
following assumptions are made for renormalization: S22 = S11 and S12 = S21,
i.e. the DUT is symmetrical.
To simplify the calculations, a non-complex impedance value is used and the
new impedance of both ports is the same.
And now the question is to what extent it is necessary to make calculations
for different values ??of port impedance, because then the DUT is not
symmetrical?? and the assumption that the S22 = S11 and S12 = S21 are equal is
not true.
Or this can be useful?
DiSlord,
I have tested your port renormalization function (called Port Z) for several values of Z like 75 and 100 ohms. It calculated S11 and S21 correctly for DUT's with the same input and output impedance. I personally don't see the need to have different Z for the input and output of a DUT. I think it just makes things more complicated and very, very few users would ever use this feature.
Roger
Roger Need