For a given power level, the ability of antenna arrays to control the direction of maximum radiation will allow for much better EIRP in the direction of communications. The CDF of EIRP, computed from a suitably large number of sample directions within the antenna simulation software, may be used to assess the directionality and effective coverage of an antenna array.
This article uses a simple example of an 8x8 patch antenna array to demonstrate the usefulness of the CDF of EIRP to characterize the ability of an array to provide good EIRP in all directions.