An array of radio antennas, usually closely spaced, in which the beam can be formed and steered by adjusting the time delay between each antenna and the receiver. As the antennas may be simple dipole antennas with no moving parts, large effective areas can be achieved relatively cheaply. Phased arrays are widely used in radar due to the rapid speed with which the beam may be steered. They also have the ability to form simultaneous multiple beams and are used in the central element of the Square Kilometre Array. The antennas at each station in the Low Frequency Array (LOFAR) form a phased array.