What is the typical coverage pattern of a semidirectional antenna?

A semidirectional antenna typically exhibits a hemispherical or cylindrical pattern due to its design, which focuses energy in a specific direction while still allowing some coverage around it. This pattern allows the antenna to transmit and receive signals effectively over a targeted area without completely omitting areas to the sides or behind, which would be the case with more directional antennas.

The hemispherical pattern enables the antenna to provide coverage to a larger area than a fully directional antenna, making it suitable for environments where coverage is needed in multiple directions but still requires a focus in a primary direction. This characteristic is particularly useful for applications such as cellular and wireless communications, where signals need to be directed towards users while still covering nearby regions.

In contrast, a circular pattern suggests equal coverage in all directions, which is not the aim of a semidirectional antenna. A linear pattern indicates a focus on a specific line or direction without breadth, while a spherical pattern suggests coverage in all directions equally, similar to the circular pattern, which also does not align with the nature of semidirectional antennas. Thus, the hemispherical or cylindrical pattern accurately depicts the typical coverage characteristics of a semidirectional antenna.