VHF/UHF FM and TV using CP don't have that pesky ionosphere, bending, flipping and twisting a signal's polarization.innate-in-you wrote: ↑Fri Mar 11, 2022 10:32 pmI've also seen the effects of analog television during events of Sporadic-E openings. Signal levels were more stable when a distant TV station was using circular polarization.
Lord knows that FM stations have preferred CP for decades.
I believe that such a signal could result in real improvement.
Once off the antenna, after one or two hops up and down through the ionosphere, an HF signal's polarization is randomized, and in fact along its way becomes essentially circularly polarized due to Faraday rotation.
Broadcasters' horizontally polarized HF arrays are steerable, and designed to be aimed to launch at optimum azimuth and elevation, to take advantage of predicted propagation paths at their operating frequencies.