A dipole antenna is a radio

Radio

Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...

 antenna  that can be made of a simple wire

Wire

A wire is a single, usually cylindrical, flexible strand or rod of metal. Wires are used to bear mechanical loads and to carry electricity and telecommunications signals. Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Standard sizes are determined by various...

, with a center-fed driven element

Driven element

In a multielement antenna array , the driven element or active element is the element in the antenna 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...

. It consists of two metal conductors of rod or wire, oriented parallel and collinear

Collinearity

A set of points is collinear if they lie on a single line. Related concepts include:In mathematics:...

 with each other (in line with each other), with a small space between them. The radio frequency

Radio frequency

Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...

 voltage is applied to the antenna at the center, between the two conductors. These antennas are the simplest practical antennas from a theoretical point of view.