Vinlove, I have read every comment in this thread by radiolistener, and everything he says is completely accurate. Your knowledge of the subject is clearly lacking, and you don't seem to be willing to accept what you're being told.
You could start by providing the screenshots/information requested so that we can investigate further. If you're not willing to, don't expect to have your question properly resolved.
Much of what
radiolistener says, is indeed correct, but he, like
vinlove, has become so absorbed in his narrative that he tends to "draw the long bow".
For example, in dismissing the suggestion of interference from a nearby high powered RF source, he says:-
For VNA there is no needs band pass filter, because it already measure SWR for specific frequency with very narrow bandwidth. NanoVNA uses PLL synthesizer for frequency sweep and SA602 mixers to shift frequency down and digitize it with 48 kHz ADC, further processing is performed in digital domain.
From my reading of that, he is asserting that having high selectivity following the mixer will guarantee narrow bandwidth at the device input.
This is, of course, not the case.
Historically Superherodyne receivers have had at least one tuned circuit before the mixer, or at the very least a bandpass filter.
With an untuned mixer &, effectively, a low IF, image interference is probable, as is intermodulation between the wanted frequency & even widely disparate frequency sources if they are strong enough.
SWR bridges are normally so insensitive that they are used with high enough power levels to make direct reading of external carriers highly unlikely.
Before the "chest beating" starts, I will state that I have been an Amateur Radio Operator since 1977.
In my working career, I spent 30 plus years working with TV & Radio Broadcasting, the latter both FM & AM (MF & HF), as well as Communications transmitters & associated equipment, so maybe my opinion might just, possibly, be worth considering.
My advice to the OP to take it to QRZ.com is based upon the fact that hams are a minority on this site, & QRZ has some people who are very experienced in the use of the type of antenna he has, & can give him advice which isn't associated with the ongoing "aggro" in this thread.
Whether he choses to take it, is up to
vinlove.