Damned, I was lookin the wrong file :)
@@ -77,7 +77,34 @@ class Coaxial( DistributedCircuit,Media ):
def from_attenuation_VF(cls, frequency=None, z0=None, Z0=50,
att=0, unit='dB/m', VF=1):
"""
+ Init from electrical properties of the line: attenuation and velocity factor.
+ Attenuation can be expressed in dB/m, dB/100m, dB/ft, dB/100ft, Neper/m or Neper/ft.
+ Default unit is dB/m. A different unit is set by the `unit` parameter.
+
+ Parameters
+ ----------
+ frequency : :class:`~skrf.frequency.Frequency` object
+
+ z0 : number, array-like, or None
+ the port impedance for media. Only needed if its different
+ from the characterisitc impedance of the transmission
+ line. if z0 is None then will default to Z0
+ Z0 : number
+ desired characteristic impedance
+ att : number, or array-like. optional
+ Attenuation of the coaxial line. The default is 0.
+ If passed as an array, should be of same size than the frequency.
+ unit : string, optional
+ Unit of the attenuation. Can be: 'dB/m', dB/100m'', 'dB/ft', 'dB/100ft',
+ 'Neper/m' or 'Neper/ft' (or 'Np/m', 'Np/ft'). The default is 'dB/m'.
+ VF : number, or array-like. optional
+ Velocity Factor VF [VF]_. The default is 1.
+ If passed as an array, should be of same size than the frequency.
+
+ References
+ ----------
+ .. [VF] : https://www.microwaves101.com/encyclopedias/light-phase-and-group-velocities
"""
# test size of parameters
