phased-array antenna

phased-array antenna

Phased array may be very simple, consisting of only two elements. Two examples of simple pairs of phased dipoles are shown in the illustration. On the left, two dipoles are spaced quarter wavelength apart in free space, and they are fed 90 degrees out of phase. This results in addition of phase in one direction and cancellation in the other. In this case, radiation pattern is unidirectional. However, phased array may have directional patterns with two, three, or even four different optimum directions. A bi-directional pattern can be obtained by spacing the dipoles at one wavelength and feeding them in phase as is shown in the illustration on the right.An antenna that consists of a number of elements and in which the direction of the beam can be changed by varying the relative phase of the signal applied to each of these elements. The phased-array antenna scans electronically.