HFSS15: Peak Directivity

Directivity is defined as the ratio of an antenna’s radiation intensity in a given direction to the radiation intensity averaged over all directions. Peak directivity, in turn, is the maximum directivity over all the user-specified directions of the far-field infinite sphere.

Directivity is a dimensionless quantity represented by
where

(1)

• U is the radiation intensity in watts per steradian in the direction specified.

• P_rad is the radiated power in watts.

• For a lossless antenna, the directivity will be equal to the gain. However, if the antenna has inherent losses, the directivity is related to the gain by the radiation efficiency of the antenna.