The antenna is a specialized transducer and in radio and electronics is an electrical device which converts electric power into radio waves, and vice versa and usually used with a radio transmitter. In transmission, a radio transmitter supplies an electric current oscillating at radio frequency to the antenna terminals, and the antenna radiates the energy from the current as electromagnetic waves. Whereas in reception, an antenna intercepts some of the power of an electromagnetic wave so to produce a tiny voltage at its terminals, that is applied to a receiver to be amplified. In computer and Internet wireless applications, the most common type of antenna is the dish antenna, used for satellite communications.
On the other hand whip antenna which is used on automobiles is of a straight, flexible wire or rod like antenna in which the bottom end is connected to the radio receiver. Whip antennas are normally designed as resonant antennas; the rod acts as a resonator for radio waves, with standing waves of voltage and current reflected back and forth from its ends. Therefore, the length of the antenna rod is determined by the wavelength of the radio waves used.