Technician exam question T3A09
Subelement T3, RADIO WAVE PROPAGATION· Group T3A
Which of the following results from the fact that signals propagated by the ionosphere are elliptically polarized?
- A.Digital modes are unusable
- B.Either vertically or horizontally polarized antennas may be used for transmission or reception (correct answer)
- C.FM voice is unusable
- D.Both the transmitting and receiving antennas must be of the same polarization
WhyBecause signals propagated by the ionosphere are elliptically polarized, either vertically or horizontally polarized antennas may be used for transmission or reception. The ionosphere twists a radio wave's polarization unpredictably as it travels through, so by the time an HF signal returns to Earth it's arrived elliptically polarized rather than cleanly vertical or horizontal, which is exactly why either a vertical or a horizontal antenna works about equally well for ionospheric contacts, unlike the strict polarization matching that matters on a direct VHF/UHF path, answer B. A, C, and D all wrongly claim some mode or matching requirement is imposed by this effect.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2026-2030 NCVEC Element 2 pool (public domain); the explanation above is original writing, see our methodology.
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