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Hi Jeff
If you use the NanoVNA-Saver and do a proper calibration then you just measure at the TX side and save the measurement to a s1p Touchstone file. Then download the ZPlots by AC6LA and open up the s1p file- Then you can shift the measurement the 100 feet to the antenna position.
Following conditions:
The cable type and manufacturer to be selected in ZPlots must be know
The cable length must be known exactly else use the Time domain of NanoVNA-saver but VF must be know for the cable
You need to have Windows EXCEL to run ZPlots
Kind regards
Kurt

-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af Jeff W6FCC via Groups.Io
Sendt: 31. marts 2020 19:31
Til: [email protected]
Emne: [nanovna-users] 100 ft Coax to Dipole Antenna - Can the NanoVNA show just the Dipole analysis?

Setup: I have a 40 meter dipole at 30 feet. Feeding with 100 ft of RG8X
Measurement: 7.200 Mhz, SWR at RADIO end of COAX can be measured (For the Analysis System -- coax + antenna)

Question: Can the Reference plane be "calculated" by software. It's the location of the antenna at the END of the Coax, discounting the Feedline, perhaps by entering the Feedline Impedance and Velocity Factor and Loss?

Asked a different way:

Can the NanoVNA be used to isolate the antenna at the far end of the COAX and somehow IGNORE the impact of the COAX itself ?

I realize the best way to check the antenna is AT the feedpoint, but that is not possible right now. I'm stuck at the Radio End of the COAX and trying to determine of the DIPOLE is too long or short.

One possible "solution" IF I could take a second piece of 100' RG8X and do the calibration at the far end (OPEN, SHORT, LOAD) and push the Reference plane out to the 100' mark.
But can it be done without a second piece of COAX ??

Has anyone calibrated their NanoVNA using a long piece of coax and doing the CAL at the end of the coax before attaching to an antenna to be tested ?

Jeff, W6FCC, 3-31-2020