Herb,
The S2P file can be in decibels and phase angle, or in real and imaginary part for each component.
In this case, I think "RI" indicates real and imaginary for each of the four S parameters (S11, S21, S22, S12) of a two port network.
The data is for only S11 and S21 here, so the last 4 entries in each line are zero.
To get dB, you compute 20*log(sqrt( real^2 + im^2)), or equivalently 10*log(real^2 + im^2).
10 * log (0.019876752^2 + 0.001359617^2) = -34.013, the insertion loss in dB.
You can also get the phase by taking the arctan (im/re).
--John Gord
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On Sun, Oct 13, 2019 at 07:58 PM, hwalker wrote:
QRP,
I had looked at the S2P file using a text editor and could see the values were
space delimited but the none of the columns were identifiable to me as the S21
log magnitude values displayed by the nanoVNA. For example at 50 kHz the
insertion loss value was -34.013 dB but none of the values at 50000 in the S2P
file below are that value.
# Hz S RI R 50
50000 -0.009529378 0.000616876 0.019876752 0.001359617 0 0 0 0
- Herb
