What is the typical coverage pattern of a semidirectional antenna?

What is the typical coverage pattern of a semidirectional antenna?

• A. A full 360-degree donut pattern around the axis.
• B. A narrow strip along a line.
• C. A hemispherical or cylindrical pattern.
• D. A random coverage with null points.

Answer: (C)

Semidirectional patterns concentrate energy into a broad region instead of radiating equally in every direction or into a single tight beam. Because of this, the 3D radiation pattern tends to fill a half-space or wrap around in the horizontal plane while remaining limited in the vertical dimension, producing a hemispherical or cylindrical shape. This shape reflects how the antenna delivers useful coverage over a wide area (like a sector or street) without spraying energy equally in all directions or focusing it into a razor-thin beam. In contrast, an omnidirectional pattern would look like a full donut around the vertical axis, and a highly directional antenna would create a narrow strip of coverage. A random pattern with nulls isn’t how real antennas radiate.

Semidirectional patterns concentrate energy into a broad region instead of radiating equally in every direction or into a single tight beam. Because of this, the 3D radiation pattern tends to fill a half-space or wrap around in the horizontal plane while remaining limited in the vertical dimension, producing a hemispherical or cylindrical shape. This shape reflects how the antenna delivers useful coverage over a wide area (like a sector or street) without spraying energy equally in all directions or focusing it into a razor-thin beam. In contrast, an omnidirectional pattern would look like a full donut around the vertical axis, and a highly directional antenna would create a narrow strip of coverage. A random pattern with nulls isn’t how real antennas radiate.