An omnidirectional antenna radiates RF energy in which pattern?

• A. Only in the forward direction.
• B. In a vertical line above the antenna.
• C. Equally in all directions around its axis.
• D. In a donut-shaped pattern around the axis.

Answer: (C)

Omnidirectional antennas are designed to radiate energy uniformly around the antenna’s axis, so in the horizontal plane the signal strength is the same in every direction as you rotate around the antenna. This azimuthal symmetry means the 3D pattern appears donut-shaped around the vertical axis, reflecting equal radiation all around rather than favoring any particular direction. That’s why describing the pattern as equally in all directions around its axis best captures how an omnidirectional antenna behaves. Descriptions that imply a single forward beam or radiation only above the antenna describe directional or elevation-focused patterns, not an omnidirectional one.