Extra exam question E9C01
Subelement E9, ANTENNAS AND TRANSMISSION LINES· Group E9C
What type of radiation pattern is created by two 1/4-wavelength vertical antennas spaced 1/2- wavelength apart and fed 180 degrees out of phase?
- A.Cardioid
- B.Omni-directional
- C.A figure-eight broadside to the axis of the array
- D.A figure-eight oriented along the axis of the array (correct answer)
WhyTwo 1/4-wavelength vertical antennas spaced 1/2-wavelength apart and fed 180 degrees out of phase create a figure-eight pattern oriented along the axis of the array. Two quarter-wave verticals spaced a half-wavelength apart and fed 180 degrees out of phase produce a figure-eight pattern oriented along the axis of the array, with the strongest radiation off the ends of the line connecting the two elements, answer D. It isn't cardioid or omnidirectional, and the figure-eight lobes point along, not broadside to, the array's axis in this particular spacing-and-phasing combination.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.
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