In a multielement
antenna array (such as a
Yagi-Uda antenna), the
driven element or
active element is the element in the antenna (typically a metal rod) which is electrically connected to the
receiver or
transmitter. In a transmitting antenna it is
driven or
excited by the
RF current from the transmitter, and is the source of the radio waves. In a receiving antenna it collects the incoming radio waves for reception, and converts them to tiny oscillating
electric currents, which are applied to the
receiver. Multielement antennas like the Yagi typically consist of a driven element, connected to the receiver or transmitter through a
feed line, and a number of other elements which are not driven, called
parasitic elements. The driven element is often a
dipole. The parasitic elements act as
resonators and couple electromagnetically with the driven element, and serve to modify the
radiation pattern of the antenna, directing the radio waves in one direction, increasing the
gain of the antenna.