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Thank you, Jim. Much appreciated. -- Rich WB2GXM------ Original message------From: Jim LuxDate: Sun, Jun 11, 2023 8:33 PMTo: [email protected];Roger Need via groups.io;Cc: Subject:Re: [nanovna-users] Anybody happens to know VF of this cable ?On 6/11/23 4:23 PM, Richard Spohn wrote:

Ok, you said "there are several ways to determine the actual VF of a cable using a NanoVNA". WHY did you stop there? Dispense with the attitude and just TELL US what these methods are!!-

1) use the NanoVNA to sweep and find out where 1/4 wavelength is (i.e.
peak in S11 magnitude). Knowing the frequency where it's 1/4 wavelength,
you can compare to free space wavelength.
2) Use the NanoVNA to measure the phase shift of the reflection at
multiple frequencies, and then fit a straight line to the measurements,
after unwrapping the phase.
3) Use the TDR function of the NanoVNA.

All of these use a known length of cable, then you measure the
electrical length of that length, and the ratio is the VF.