One method described online on YouTube and in social media is the 90° method
as I will call it.
The reason why people make measurements at +/- 90 degrees on the smith chart is because the measurement accuracy using the shunt configuration when trying to measure the nominal value of an inductor or capacitor is highest at 0+j50 ohms (or 0-j50 ohms… OD).
To be clear, this is the phase of s11 or Γ being + or – 90° as applicable.
Is there something optimal when phase of s11 is + or – 90°?
Does the software / firmware / hardware give significantly more accurate response under such a termination?
Above is a diagram from a HP publication, slightly altered to suit the discussion. Continue reading NanoVNA-H4 – inductor challenge – part 7