Which statement accurately describes an omnidirectional antenna?

An omnidirectional antenna is designed to radiate radio frequency (RF) power uniformly in a 360-degree pattern, but only in one plane. This plane is the horizontal or azimuth plane. In the vertical or elevation plane, the radiation pattern is concentrated, creating a shape often described as a donut or toroid. This results in weaker signal strength directly above and below the antenna. This characteristic makes them ideal for providing coverage to devices spread out over a flat area, such as an office floor.

A. The elevation plane is the vertical plane, where an omnidirectional antenna's radiation is concentrated and not equal in all directions.

B. The vertical plane is the elevation plane. Power is not radiated equally in this plane; it has nulls above and below the antenna.

C. This describes a directional antenna, which focuses its power in a specific direction rather than radiating it equally in a plane.

1. Aruba Networks, an HPE Company. (2020). Antennas and Accessories Guide. Page 5, "Antenna Characteristics". "Omnidirectional antennas provide 360-degrees of coverage in the azimuth (horizontal) plane."

2. Kurose, J. F., & Ross, K. W. (2021). Computer Networking: A Top-Down Approach (8th ed.). Pearson. Chapter 6, Section 6.3.2, discusses antenna patterns, explaining that omnidirectional antennas radiate in all directions in one plane.

3. MIT OpenCourseWare. (2011). 6.002 Circuits and Electronics, Spring 2007. Lecture 22 - Antennas. The lecture notes explain that an ideal dipole antenna (a type of omnidirectional antenna) has a toroidal (donut-shaped) radiation pattern, which is uniform in the azimuth plane.