On 3/4/22 7:43 AM, Miro, N9LR via groups.io wrote:
In HAM world, one of key uses for nano is antenna tuning, or at least better understanding what my TX is going to see.
Very rarely we get a luxury to connect nano directly to antenna feed point over t-line that can be used in calibration. More often is that I have a random length of coax in place, and can only measure what is at that point. In those cases, it does not matter what I have as a pigtail from nana to antenna system.
With full appreciation of what that means (don't know cable losses, cable rotates complex impedance, only SWR reflects what's at the antenna side, ...), and given that a pigtail on nano side is also random selection from immediately available ones but it's length is much shorter then lambda, I need a quick way to calibrate nano with respect to nano's port
Now question - what happens when I "reset calibration" on nano - will that in effect be equivalent to calibrating nano directly at the port?
If not, what is the quickest way to get calibration that will get me going quickly, without the need for SOL?
You can do a SOL calibration at the NanoVNA (that takes out the basic instrument issues) - and then measure your antenna.? As you say, the coax will add a phase shift to the S11, and will show better match (more negative S11 magnitude, lower SWR).
cables.png is? two cables measured with the far end open.
The other plots are antennas measured using the cable calibration and not.
If you use some PC software, you can do a calibration of the coax, once, and save that. Then you can fire up the NanoVNA, tell the software to use the "with coax" calibration, and measure your antenna.
