Transmitter is the name of the equipment used for broadcasting. A transmitter is an electronic device which generates and amplifies a carrier wave, which it mixes with the information to be disseminated and then broadcasts the resulting signal from an antenna.
Transmitters do this by first converting electric power from a battery or electrical mains into radio frequency. An electronic information signal in the form of an audio (sound) signal from a microphone or a video (image) signal from a video device such as a camera or a computer is mixed with the radio frequency generated by the transmitter through a process called modulation. The radio waves generated by the process of modulation is called the carrier signal.
The carrier signal is then transmitted from an antenna. The antenna may be enclosed in the same case as the transmitter, as in portable devices, or it may be mounted on top of a building or on a separate tower, as it is in TV or radio stations.