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I understand the value and significance of tuning an antenna to be resonant. I think I understand the previous post about, quarter and half wavelengths of feedline, resistance and reactance and the

A new release of Octave has been announced. https://lwn.net/Articles/840050/ "On November 26, version 6.1 of GNU Octave, a language and environment for numerical computing, was released. There are

Great video, Alan.https://youtu.be/r6UHITd3AWUThanks, Jim - W5SWVSent from my Verizon, Samsung Galaxy smartphone

Hi all, the S21 method for measuring very high impedance in general, including CMC works quite OK. I hope the feature will be added to nanovna-saver, then it would be really easy:

Placing the nanovna on the transmitter side of the coaxial cable, you must perform the SOL calibration on the antenna side, ie on the terminal of the cable that is connected to the antenna. This way

Yes, this is normal. If your antenna's resonant point (where the reactance goes to zero) is not exactly at Z0 (line impedance), then the resonant point *will* move as you add transmission line.

When in the shack you are not measuring the resonance frequency of the antenna. You are measuring an impedance which is set by both the antenna and the length of coax. Both R and X will change, unless

I'd guess that the coax is "part of the antenna".? When you measure the Z at the feedpoint, I assume you disconnected the coax and connected the VNA there. Try connecting a short jumper from shield

Most likely the coax cable is part of the "ground" structure of your antenna. Without is, the resonance frequency will be higher. The same happens e.g. on a 2.4 GHz pcb trace pifa antenna. The size of

02 January 2021 Happy New Year all! If I do a OSL at the end of the coax to my horizontal top band loop and measure at the antenna end of the coax I see quite a lot higher frequency resonance than

Yes I have one side of the pair attached to center pin of CH00 and CH01. So center pin to center pin via one side of the pair, and the other side of the pair going to common on each side. Instead, I

The way the picture shows you have connected the CMC, you are not measuring CM rejection but rather DM which should be low. You need to tie both ends of the choke together and feed CM and sense CM.

I am such an idiot. Where you see type 61 in my text, please replace it with type 31. Sorry!!

Sirs, you have thrown down the gauntlet, Sir, and I accept your challenge. In my previous life, I was a more than adequate spreadsheet wiz. So I should be able to handle this job. haha. First, the

If you just want the characteristic impedance and not a plot of instantaneous impedance over time delay, there is a very simple relationship.? Average or characteristic impedance for a coax or any?

John, you gave good details on my scheme.? Perhaps I should have been more explicit but apparently I had it right, basically. Bob

Bob, I don't think you are remembering quite right. For the first method: Set the frequency range for Start 50kHz, Stop 500MHz. Calibrate (open, short, load) the VNA at the point where the unknown

Yeah works fine ! Mine was around 6€ Op za 18 apr. 2020 12:43 schreef hwalker <herbwalker2476@...>:

Use Smith chart display.? Sweep the frequency to find the place where the curve passes the first quarter of the circle, which is one eighth wave.? Move the marker to that spot and read the

How can I use a NanoVNA to measure the characteristic impedance of an unmarked length of coaxial cable? I have a NanoVNA-H4. I saw another thread here titled "characteristic impedance," but the