Which antenna is uni-directional?

Which antenna is uni-directional?

• A. Fan
• B. Whip
• C. Dipole
• D. Yagi

Answer: (A)

Directionality in antennas comes from how their radiation pattern concentrates energy. A uni-directional antenna sends most of its energy in one primary direction, giving higher gain in that direction and less elsewhere. The Yagi-Uda antenna is a classic example of a uni-directional design. It uses a driven element plus one or more parasitic elements (reflector and directors) to reinforce radiation in a single forward direction, forming a narrow beam. That focused forward pattern is what makes it uni-directional. A whip antenna is typically a vertical monopole and tends to radiate more or less uniformly around the horizon (an omnidirectional pattern), so it’s not uni-directional. A dipole produces a figure-8 pattern with strong lobes in two opposite directions, which is bidirectional rather than single-direction. A fan-beam configuration can be directional in one plane but is not as clearly defined or universally recognized as the standard uni-directional option as the Yagi. So, the antenna designed to be uni-directional in common practice is the Yagi.

Directionality in antennas comes from how their radiation pattern concentrates energy. A uni-directional antenna sends most of its energy in one primary direction, giving higher gain in that direction and less elsewhere.

The Yagi-Uda antenna is a classic example of a uni-directional design. It uses a driven element plus one or more parasitic elements (reflector and directors) to reinforce radiation in a single forward direction, forming a narrow beam. That focused forward pattern is what makes it uni-directional.

A whip antenna is typically a vertical monopole and tends to radiate more or less uniformly around the horizon (an omnidirectional pattern), so it’s not uni-directional. A dipole produces a figure-8 pattern with strong lobes in two opposite directions, which is bidirectional rather than single-direction. A fan-beam configuration can be directional in one plane but is not as clearly defined or universally recognized as the standard uni-directional option as the Yagi.

So, the antenna designed to be uni-directional in common practice is the Yagi.