General exam question G3C04
Subelement G3, RADIO WAVE PROPAGATION· Group G3C
What does the term “critical angle” mean, as applied to radio wave propagation?
- A.The long path azimuth of a distant station
- B.The short path azimuth of a distant station
- C.The lowest takeoff angle that will return a radio wave to Earth under specific ionospheric conditions
- D.The highest takeoff angle that will return a radio wave to Earth under specific ionospheric conditions (correct answer)
WhyThe critical angle is the highest takeoff angle that will still return a radio wave to Earth under specific ionospheric conditions. The critical angle is the highest takeoff angle, most nearly straight up, that a radio wave can leave at and still be refracted back down to Earth under the current ionospheric conditions, rather than punching through into space, answer D. It isn't the lowest such angle, and it has nothing to do with a distant station's azimuth, long or short path.
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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