What is antenna gain? How does antenna gain relate to the pattern or directivity?
A. The gain of any antenna is essentially a specification that quantifies how well that antenna is able to direct the radiated radio frequency (RF) energy into a particular direction. Thus, high-gain antennas direct energy more narrowly and precisely, and low-gain antennas direct energy more broadly. With dish-type antennas, for example, the operation is exactly analogous to the operation of the reflector on a flashlight. The reflector concentrates the output of the flashlight bulb into one predominant direction in order to maximize the brightness of the light output. This principle applies equally to any gain antenna, because there is always a trade-off between gain (brightness in a particular direction) and beam width (narrowness of the beam). Therefore, the gain and pattern of an antenna are fundamentally related. They are actually the same thing. Higher gain antennas always have narrower beamwidths (patterns), and low gain antennas always have wider beam widths.
