An antenna array is a group of antennas from which the signals are combined to form a single beam. It can include two or more antennas, while some arrays can have up to thousands of individual signal radiating components. Antenna arrays are used to improve the signal quality, minimize interference, and focus the signal in a certain direction. They can also be used to detect where incoming signals are coming from. Also called a phased array antenna, the device enables beams from each antenna to cause interference which is used for steering signals.
The phase of each signal from each antenna is shifted to create one radiating beam. A single beam then moves in one direction, within a field of view up to 120°. All of the functions of the antenna array are controlled by a computer, and the position of the beam can be moved within a fraction of a second. One of the most significant benefits of antenna arrays is that the systems will work even if one antenna fails. The quality of operation will diminish but the array will continue to work.
There are different kinds of antenna arrays. A linear array has one phase shifter, and antennas arranged in a line. The rays can be deflected in only one horizontal or vertical plane, but a planar array can steer beams in two planes. This type is more complex and each antenna includes a phase shifter of its own. A frequency scanning antenna array steers a beam according to the frequency of the signal; return signals can be displayed in three dimensions.
An antenna array can take various forms. It can be etched onto a circuit board, or its elements can be configured on top of a cellular phone tower. A microstrip antenna array is very small and is often printed on circuit boards for mobile phones. Large antenna arrays are sometimes used by military installations.
During the design stage, an antenna array is often modeled by a computer. The calculations for determining the size and beam forming capacity of each antenna in the array are complex. Computer software that can solve difficult mathematical problems is used for this purpose, and computers need to have substantial power to support this capability. Some software programs can also visualize the beam patterns under various conditions with a lot of detail. The function of an antenna array can therefore be determined before it is even built.