General exam question G9B03
Subelement G9, ANTENNAS AND FEED LINES· Group G9B
Which of the following best describes the radiation pattern of a quarter-wave ground-plane vertical antenna?
- A.Bi-directional in azimuth
- B.Isotropic
- C.Hemispherical
- D.Omnidirectional in azimuth (correct answer)
WhyA quarter-wave ground-plane vertical antenna has a radiation pattern that is omnidirectional in azimuth. A quarter-wave ground-plane vertical radiates equally in every compass direction around the antenna, an omnidirectional pattern in azimuth, while still having real shape (nulls straight up and down) in elevation, answer D. It isn't bidirectional, isn't a true isotropic radiator (nothing physical is), and "hemispherical" doesn't accurately describe its azimuthal shape, so A, B, and C are wrong.
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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