skrf.qfactor.Qfactor.Q_circle

Qfactor.Q_circle(opt_res=None, A=None)[source]

Q-circle diameter.

The diameter of the Q-circle (as displayed in a VNA) provides a visual indication of whether the coupling is strong or weak [MAT58].

Parameters:

  • opt_res (None or OptimizedResult. Default is None.) – Solution produced by the fit() method. If None, uses the solution previously calculated, if performed.

  • A (None of float. Default is None.) – Scaling factor as defined in MAT 58 [MAT58]. For reflection resonance type, can be set as None to use the magnitude of the fitted detuned reflection coefficient S_V

Returns:

  • diam (float) – Q-circle diameter d.

  • S_V (complex) – Off-resonance Reflection Coefficient.

  • S_T (complex) – Tuned Reflection Coefficient.

Return type:

list

References

[MAT58] (1,2)

“Q-factor Measurement by using a Vector Network Analyser”, A. P. Gregory, National Physical Laboratory Report MAT 58 (2021) https://eprintspublications.npl.co.uk/9304/, section 2.5, eqn. (31).