What is Phased Array ?

In antenna theory, a phased array is an array of antennas in which the relative phases of the respective signals feeding the antennas are varied in such a way that the effective radiation pattern of the array is reinforced in a desired direction and suppressed in undesired directions.

An antenna array is a group of multiple active antennas coupled to a common source or load to produce a directive radiation pattern. Usually, the spatial relationship of the individual antennas also contributes to the directivity of the antenna array. Use of the term "active antennas" is intended to describe elements whose energy output is modified due to the presence of a source of energy in the element (other than the mere signal energy which passes through the circuit) or an element in which the energy output from a source of energy is controlled by the signal input. One common application of this is with a standard multiband television antenna, which has multiple elements coupled together.

The relative amplitudes of — and constructive and destructive interference effects among — the signals radiated by the individual antennas determine the effective radiation pattern of the array. A phased array may be used to point a fixed radiation pattern, or to scan rapidly in azimuth or elevation.

When phased arrays are used in sonar, it is called beam forming. The phased array is used for instance in optical communication as a wavelength-selective splitter.

Usage

· Broadcasting

· Naval usage

· Space probe communication

· Weather research usage

· Optics

· Radio-Frequency Identification

· Human-Machine Interfaces (HMI)

Different types of phased arrays

There are mainly two kinds of phase arrays:

1. Dynamic phased array – an array of variable phase shifters are used to move the beam

2. Fixed phased array – the beam position is stationary with respect to the array face and the whole antenna is moved