addendum to my previous reply ...
For those who are using NanoVNAsaver, I had a quick look into the source code for place(s) of hard-coded Z_0 = 50 ohms.
I believe (but have not tested ...) that if you change all occurences of 50 to 75 in the list below that all values and calculations in
NanoVNAsaver would be done with a reference of Z_0 = 75 ohm:
NanoVNASaver/Calibration.py: g = (Zsp / 50 - 1) / (Zsp / 50 + 1) * cmath.exp(
NanoVNASaver/Calibration.py: g = ((Zop / 50 - 1) / (Zop / 50 + 1)) * cmath.exp(
NanoVNASaver/Calibration.py: g = (Zl / 50 - 1) / (Zl / 50 + 1) * cmath.exp(
NanoVNASaver/RFTools.py: def impedance(self, ref_impedance: float = 50) -> complex:
NanoVNASaver/RFTools.py: def shuntImpedance(self, ref_impedance: float = 50) -> complex:
NanoVNASaver/RFTools.py: def seriesImpedance(self, ref_impedance: float = 50) -> complex:
NanoVNASaver/RFTools.py: def qFactor(self, ref_impedance: float = 50) -> float:
NanoVNASaver/RFTools.py: def capacitiveEquivalent(self, ref_impedance: float = 50) -> float:
NanoVNASaver/RFTools.py: def inductiveEquivalent(self, ref_impedance: float = 50) -> float:
NanoVNASaver/RFTools.py:def gamma_to_impedance(gamma: complex, ref_impedance: float = 50) -> complex:
NanoVNASaver/RFTools.py:def impedance_to_norm(z: complex, ref_impedance: float = 50) -> complex:
NanoVNASaver/RFTools.py:def norm_to_impedance(z: complex, ref_impedance: float = 50) -> complex:
NanoVNASaver/RFTools.py:def reflection_coefficient(z: complex, ref_impedance: float = 50) -> complex:
NanoVNASaver/Windows/CalibrationSettings.py: self.load_resistance.setText(str(self.app.settings.value("LoadR", 50)))
NanoVNASaver/Windows/TDR.py: self.step_response_Z = 50 * (1 + self.step_response) / (1 - self.step_response)
