That has no effect on ground based line of sight UHF and higher signals that don't pass through the ionosphere.
What? The guys on the ISS (among others) would be interested to hear about your theory of UHF and the ionosphere!
Generally, it's the lower frequencies that are either reflected or absorbed by the ionosphere. Depending on the amount of solar activity the maximum frequency that will bounce off can get quite high. 50 MHz F2 propagation is rare but not unheard of. I'm not sure how high it has ever gotten.
144 and up often reflects off clouds of ionization at the E layer height -- I've worked into New England and Canada on 2m -- but that's not quite the same (and don't ask me to explain because I'm right at the limit of my knowledge as it is!).
Could solar activity affect 850 MHz signals? I don't actually know but at the same time, I doubt that's what's going on here.
All radio signals are line of sight; some just get reflected or refracted in interesting ways. Which is what ham radio is all about. :lol:
