What characteristic of an antenna is primarily described by its gain?

• A. The directionality of the radiated signal
• B. The physical size of the antenna
• C. The frequency range of operation
• D. The materials used for construction

Answer: (A)

Gain refers to how effectively an antenna can radiate or receive signals in a particular direction compared to a reference antenna, typically an isotropic radiator. Therefore, the primary characteristic of an antenna described by its gain is its directionality. An antenna with higher gain indicates that it focuses the energy more in a specific direction, allowing for stronger signals in that direction while potentially reducing signals received or transmitted from other angles.

For instance, a directional antenna, such as a Yagi or a parabolic dish, has a high gain because it concentrates the energy in a narrow beam. This characteristic is crucial in applications where long-range communication is needed or when targeting a specific radio station. The other options, while related to antennas, do not define gain. Physical size, frequency range, and materials influence performance but do not directly describe what gain measures.