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Re: 100 ft Coax to Dipole Antenna - Can the NanoVNA show just the Dipole analysis?

 

You can only measure the actual antenna impedance remote from the antenna, with a 1/2 wavelenght of coax or feedline (x the velocity factor of the feedline), measured at a single frequency of interest.

If you are going to use a multi-band antenna, you particularly want to measure the impedance at the coax input point in order to know what the transmitter will be actually looking at, as a function of the antenna/feedline system.
Ray,
W4BYG

On 3/31/2020 4:27 PM, Jeff W6FCC via Groups.Io wrote:
Carey,

If the antenna is NOT 50 ohms (it's actually an offset multi-band dipole with a 4::1 balun transformer), or not resonant, I was thinking that the COAX would introduce some problems.
They do use small runs of COAX for matching, that's what I was thinking, that the SWR would not be constant across the length of the COAX if the antenna was not 50 ohms resonant.

I was looking for a way to put the imaginary connector to the antenna at the far end of the COAX but maybe that's not going to solve anything.

Jeff





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