On 3/22/23 9:33 AM, Fran?ois wrote:
S21 is typically given in dB magnitude plus phase, so gain would be
10^(mag/20)..
If you have S21 as a linear complex value, then the gain is just the
magnitude sqrt(a^2 + b^2). Phase is atan(b/a)
Thank you but I want to start from the values in the .s2p file
Starting from a .s2p file coming out of nanovana-saver, I have for example
211618 -0.6282719521724260 0.48020111742544200 0.48752110556607600 0.50280646366029200 0 0 0 0
I would assume that S21 is the pair starting with 0.487.. and 0.5028...
one thing that is important is to check the header of the .s2p and see whether it is giving you data in dB and degrees, or as complex linear.
It seems to me that A priori, S21 is what is in yellow
The image isn't readable (.wmz and .mso files?) - the png is just the equation for S11 in terms of impedance.
The marker for this frequency tells me
S21 Polar 0.72 v 44.62¡ã
That must be linear magnitude and phase, not dB. I calculate the magnitude as around 0.7 (see below) and that would be -3dB if converted to dB.
sqrt(0.485^2 + 0.5028^2) is about 0.70
atan2 (0.485, 0.5028) is about 45.9
So that's pretty close (is it possible that the cursor is pointing at the point "next" to the one in the .s2p, or is it currently sweeping, so you're seeing the sweep to sweep variation).
(the angle is close to 45 degrees, if x and y were swapped you get 44.1 degrees, but since the imaginary part is bigger than the real part, the angle must be >45)
How to recalculate this value from the S21 (and S11 ?)
I know how to recalculate Z=A+jB from -0.6282719521724260 0.48020111742544200
We start from the fact that
I want to do the same for gain
Gain is 0.70
