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

A vertical whip antenna typically radiates omnidirectionally in the horizontal plane, which means it sends and receives signals equally in all directions around it. This characteristic is best represented by a circular radiation pattern.

In an omnidirectional radiation pattern, the antenna's performance is uniform in the horizontal plane, making it ideal for communication applications where signals are needed from all directions. This is fundamentally why the choice of a circular radiation pattern accurately describes the behavior of a vertical whip antenna.

The other options represent various directional patterns. A figure eight and a cardioid pattern are more applicable to antennas that have directivity and prefer reception or transmission from specific angles. An ellipse does not accurately express the equal strength of radiation in all directions that typifies a vertical whip antenna. Thus, the circular radiation pattern is the most suitable and accurate description.