General exam question G3B05
Subelement G3, RADIO WAVE PROPAGATION· Group G3B
How does the ionosphere affect radio waves with frequencies below the MUF and above the LUF?
- A.They are refracted back to Earth (correct answer)
- B.They pass through the ionosphere
- C.They are amplified by interaction with the ionosphere
- D.They are refracted and trapped in the ionosphere to circle Earth
WhyRadio waves with frequencies below the MUF and above the LUF are refracted back to Earth by the ionosphere. Frequencies that fall between the LUF and the MUF for a given path are exactly the ones the ionosphere refracts back down to Earth, that's the usable window the two figures define, answer A. Passing straight through, being amplified, or getting trapped and ducted around the Earth all describe different, incorrect outcomes.
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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