I endorse this comment fully!
I have worked with VNAs on and off in my working life for the last ten years or so, and I only wish I'd seen this presentation ten years ago!
It is the most succinct explanation of VNAs in general, and the "new" NanoVNA in particular. Worth viewing again and again until as much knowledge as you can handle sinks in!
It's probably working your way through the other G-QRPClub videos if you have time, there's some seriously good stuff in there!
73
Martin - G4FUI
Martin Rigby