devicelab
Whacker Extraordinaire
Here's a sweep of my Diamond D3000N discone antenna. The antenna uses 75FT of LMR400 at approximately 30FT above ground level. In this sweep, I'm using only a RTL-SDR FM notch filter.

Updated screenshot.It would be nice to see more detail, like limit return loss to 30dB or maybe 40dB and SWR to 3:1 or 4:1 max.
Updated screenshot.
No I appreciate it... it's making me learn how to use the NanoVNA. This is much easier on a SA as (some) of it's done for you.Don't mind me said the guy who used to teach classes on spectrum analyzers and VNAs.
When my workplace got a new drum of RG58, maybe 1000ft, I measured its SWR when nothing where connected to the other end. It was a perfect 1.0...so at the higher frequencies whatever the antenna is doing is being masked by at least several dB.