Phased Array Antennas
15.1. Directivity, Power Gain, and Effective Aperture
Radar antennas can be characterized by the directive gain GD, power gain G, and effective aperture Ae. Antenna gain is a term used to describe the ability of an antenna to concentrate the transmitted energy in a certain direction. Directive gain, or simply directivity, is more representative of the antenna radiation pattern, while power gain is normally used in the radar equation. Plots of the power gain and directivity, when normalized to unity, are called the antenna radiation pattern. The directivity of a transmitting antenna can be defined by
The radiation intensity is the power-per-unit ...