Eichard Fry wrote:
"...and subparts (c) and (e) of that figure clearly show the high-angle
sidelobe cebtered at about 58 degrees elevation from an 0,64-lambda
monopole that may cause self interference..per Roy Lewallen`s post
earlier in this thread."

All too true. In AM broadcasting, at night the sky wave may interfere
with the ground wave beyond the skip zone.

In HF transmissions, the ground wave is likely exhausted in short order
so that the sky wave is the only signal available at considerable
distances. There will be no ground wave to beat with the sky wave to
cause fading but there are numerous paths for the sky wave which produce
plenty of fading without adding any ground wave to the mix.

Best regards, Richard Harrison, KB5WZI