A vertical (whip) antenna has a radiation pattern best described by?

The radiation pattern of a vertical (whip) antenna is best described as a circle. This is because a vertical antenna radiates energy equally in all horizontal directions. When observing the radiation pattern in a horizontal plane, the energy is distributed uniformly around the antenna, creating a circular pattern.

In practical terms, this means that the signal strength is the same in all directions at a given distance from the antenna, which is ideal for many communication applications. This characteristic helps to ensure reliable communication with minimal directional bias.

Other patterns, such as a figure eight or a cardioid, imply directionality where the antenna would radiate more power in certain directions and less in others, which does not apply to a vertical whip antenna that, by design, provides omnidirectional coverage in a horizontal plane. Thus, the correct answer highlights the fundamental behavior of a vertical antenna as it radiates effectively around itself.