General exam question G3B11
Subelement G3, RADIO WAVE PROPAGATION· Group G3B
What happens to HF propagation when the LUF exceeds the MUF?
- A.Propagation via ordinary skywave communications is not possible over that path (correct answer)
- B.HF communications over the path are enhanced
- C.Double-hop propagation along the path is more common
- D.Propagation over the path on all HF frequencies is enhanced
WhyWhen the LUF exceeds the MUF for a path, ordinary skywave communication over that path is not possible. When the LUF for a path rises above the MUF, there's no frequency left in between that's both low enough to survive the trip and high enough to refract back to Earth, so ordinary skywave propagation over that path simply isn't possible, answer A. It doesn't enhance communications, and double-hop propagation isn't specifically favored by this condition either, it's the opposite, the usable window has closed entirely.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2023-2027 NCVEC Element 3 pool (public domain); the explanation above is original writing, see our methodology.
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