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I have a NanaVNA-H4,

And how would I use it to make an exact 1/2 wave or multiple there-of coax?
1/2, 1.0, 1.5, 2.0, etc...
Joe WB9SBD

Joe,
If you short the far end of the coax and connect the NanoVNA to the other end, each half wave will read a short on the VNA. half wavelengths repeat the impedance on the end, quarter wavelengths invert the impedance at the end, i.e. a short will look like an open.
Gary
W9TD

Well that makes it simple doesn't it.

Make it slightly longer than expected, then partially cut through the cable or snip it completely off as needed for the short at freq! Cool!

Joe

Hi
a Calibrated smith diagram can show you easily the serial resonance frequency and the parallele one ( Xr = 0 Omh ) ,
- use the 401 sweep points option to have maximum frequency accuracy .
- Stimulus band should be selected to be the minimum needed .
- Calibration and measurement prefered after at least 10 minutes for thermal stability .

you can use open coax terminaison or short one , they should give approximatly the same results .

73's Nizar.

All info here is accurate. BUT, to save time, calculate the "electrical"
wavelength needed mathematically for the "rough" estimate. Wavelength =
300/frequency (MHz) multiplied by the specified Velocity Factor from the
manufacturer. Then, add several inches for "tuning" via the VNA.

Michael L Robinson, KC0TA

“In the beginning of a change the Patriot is a scarce man, and brave, and
hated and scorned. When his cause succeeds, the timid join him, for then it
costs nothing to be a Patriot.” ― Mark Twain

When Tyranny becomes Law, Revolution becomes Duty!






On Sun, Mar 30, 2025 at 2:44?PM Team-SIM SIM-Mode via groups.io <sim31_team=
[email protected]> wrote:

Hi
a Calibrated smith diagram can show you easily the serial resonance
frequency and the parallele one ( Xr = 0 Omh ) ,
- use the 401 sweep points option to have maximum frequency accuracy .
- Stimulus band should be selected to be the minimum needed .
- Calibration and measurement prefered after at least 10 minutes for
thermal stability .

you can use open coax terminaison or short one , they should give
approximatly the same results .

73's Nizar.