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Nice find!

I ran into a research paper on measuring capacitors using a VNA that might be of interest. It analyzes capacitance and ESR accuracy for the S11 reflection, S21 series-through, and S21 shunt-through

Have you turned on the VNA's Smith chart? At what frequencies thru your sweep does the trace cross the chart's center (no reactance) line? Those are your antenna's resonant frequencies. The one

Joe, I got licensed a decade after you and did not have a chance to use a balun or 50 ohms coax then. My 40 and 80m dipoles were fed by 75 ohms TV cable. I did not have an SWR meter either. Still I

Yup! The Balun Craze is a new Generation thing. Got licensed in 1975, Never ever heard of a Balun. All my dipoles were direct feed. Only till recently has the myth of a dipole without a balun will not

It's measuring the 3rd harmonic which shows a nice low SWR. how far below 172 Mhz did you start your scan? Joe WB9SBD

I have never seen a problem feeding a dipole directly with an unbalanced feedline. The last dipoles I had up (which were for 40 and 30 meters) were just fed by connecting the two leads of the coax

Bob, Would you suggest a voltage balun or current balun at antenna feedpoint? One ham told me that if you use a voltage balun, it can bring down the high noise I have on 80m. Regarding the original

Hello Hobride, Unfortunately you have not supplied a photo of your test setup. A dipole is balanced at the feedpoint, your VNA is unbalanced. I suspect your problem is that you do not have a balun or

You did not indicate the range of your sweep. Try setting the sweep range to 150MHz to 190MHz, recalibrate open/short/load, then measure. I suspect that you will find the lowest VSWR near 171MHz,

The attchment is missing

Hello, yes, I have also performed an OSL calibration in the 150-190 MHz range. The SWR at 172 MHz is 4.5 I made the legs from copper wire with ~1mm diameter. The legs are mounted in a plastic tube.

Did you do an OSL calibration of the NanoVNA over the frequency range of interest? How is the antenna supported? How is it fed? I cannot imagine an antenna being that far off. Your length calculations

Hello everyone, I have bought a NANO VNA H4 to build simple dipole antennas. Now I have made a simple dipole antenna for testing. This should be tuned for 172 MHz. The total length is ~83 cm (2,72

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 . -

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

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

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

Have you tried reducing the sweep range? It might be informative to reduce the sweep to 25MHz starting at 300MHz, OSL calibrate at the measurement plane and run the sweep. Then move up 25MHz

You might be receiving strong signals with that antenna, that interfere with the nanoVNA's measurements. If that's the case, at least some of the excursions to negative resistance should not repeat on