How does a Phased Array antenna work?
In a classic parabolic reflector antenna, the reflector is illuminated from a single point (feeder) and the signal is scattered back in order to produce a plane wave. It is also possible to produce a plane wave by a flat antenna composed by an array of radiators, all fed in-phase with the same signal: the waves from the radiators will combine to form a plane wave (see figure below). In the phases of the signals feeding the radiators have an appropriate relative phase shift, their waves will still combine to produce a plane wave, but the direction of propagation will not be anymore orthogonal to the antenna surface, by an amount depending of the phase shift between the radiators.. By properly controlling the phases of the individual radiators, it is then possible to synthesize wavefronts propagating in different directions, thus steering the antenna electronically (typically up to +/- 45°). This is achieved by way of special electronic devices, called phase shifters, or with other techn
