Extra exam question E9C02
Subelement E9, ANTENNAS AND TRANSMISSION LINES· Group E9C
What type of radiation pattern is created by two 1/4-wavelength vertical antennas spaced 1/4- wavelength apart and fed 90 degrees out of phase?
- A.Cardioid (correct answer)
- B.A figure-eight end-fire along the axis of the array
- C.A figure-eight broadside to the axis of the array
- D.Omni-directional
WhyTwo 1/4-wavelength vertical antennas spaced 1/4-wavelength apart and fed 90 degrees out of phase create a cardioid pattern. Two quarter-wave verticals spaced a quarter-wavelength apart and fed 90 degrees out of phase produce a cardioid pattern, a single, heart-shaped lobe with one deep null, the classic combination of quarter-wave spacing and quadrature phasing, answer A. It doesn't produce a figure-eight pattern in either orientation, and it isn't omnidirectional, those describe other spacing-and-phasing combinations.
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.
Related questions
- E9C01What 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?
- E9C03What type of radiation pattern is created by two 1/4-wavelength vertical antennas spaced 1/2- wavelength apart and fed in phase?
- E9C04What happens to the radiation pattern of an unterminated long wire antenna as the wire length is increased?
- E9C05What is the purpose of feeding an off-center-fed dipole (OCFD) between the center and one end instead of at the midpoint?
- E9C06What is the effect of adding a terminating resistor to a rhombic or long-wire antenna?