# Directivity |  | In electromagnetics, **Directivity** is a parameter of an antenna or optical system which measures the degree to which the radiation emitted is concentrated in a single direction. It is the ratio of the radiation intensity in a given direction from the antenna to the radiation intensity averaged over all directions. Therefore, the directivity of a hypothetical isotropic radiator is 1, or 0 dBi. | |-|-| | | wikipedia:: [Directivity](https://en.wikipedia.org/wiki/Directivity) |