A
dimensionless
quantity that
replaces the
term directive gain in the
IEEE definitions for
antennas.
"Directivity is the
ratio of the
radiation intensity in a given
direction from the antenna to the radiation intensity averaged over all directions. The
average radiation intensity is
equal to the total
power radiated by the antenna divided by (4 *
π). If direction is not specified, the direction of
maximum radiation intensity is implied."
-
Definition from the 1983 version of the IEEE Standard Definitions of Terms for Antennas