Which statement accurately describes a ground-plane antenna?

• A. A vertical monopole above a conducting surface
• B. A dipole with no reference ground
• C. A long-wire vertical with counterpoise
• D. A Yagi with multiple elements

Answer: (A)

A ground-plane antenna is a vertical monopole placed over a conducting surface. That surface serves as a mirror, creating an image of the radiator so the current flows both on the vertical element and its reflection in the plane. Together they act like a half-wavelength dipole, with the ground plane completing the electrical path.

This arrangement gives an essentially omnidirectional pattern in the horizontal plane and is typically designed so the vertical element is a quarter-wavelength above the plane to achieve a good impedance match. The ground plane can be natural earth, a metal surface, or an artificial plane made of radials, as long as it’s large enough and conductive at the operating frequency.

The other configurations aren’t ground-plane antennas: a standalone dipole has no reference ground or mirror; a vertical with a counterpoise uses separate conductors rather than a conducting plane as the return path; and a Yagi is a directional multi-element antenna, not a ground-plane radiator.