Radio communication

Radio communication transmits information by modulating radio-frequency electromagnetic waves and detecting them at a receiver. It works without a wired connection between transmitter and receiver.

Electromagnetic radiation: Electromagnetic radiation is energy propagated through space as oscillating electric and magnetic fields. Radio waves are the electromagnetic carriers that transmit the modulated signal.
Radio spectrum: The radio spectrum is the portion of the electromagnetic spectrum used for radio-frequency signals. Radio communication operates within this range of frequencies.
AM broadcasting: AM broadcasting transmits audio by varying a radio carrier's amplitude in proportion to the program signal. It is a long-established radio service using amplitude modulation.
Wired communication: Wired communication carries signals through physical conductors or optical fibers. Unlike radio links, it requires a transmission medium connecting the communicating endpoints.
Radio broadcasting: Radio broadcasting distributes audio or other content from transmitters to many receivers. It made one-way wireless communication a mass medium.
Radio transmitter: A radio transmitter generates radio-frequency signals and sends them through an antenna. It converts information into a radio signal suitable for transmission.
Frequency: Frequency is the number of cycles of a repeating event per unit time. A radio signal's frequency helps determine its propagation, antenna size, and permitted use.
FM broadcasting: FM broadcasting transmits audio by varying a carrier's frequency in proportion to the program signal. It is a widely used radio service known for high-fidelity audio.
Optical communication: Optical communication transmits information using light, commonly through optical fiber or free space. It uses optical-frequency carriers rather than radio-frequency waves.
Wireless telegraphy: Wireless telegraphy sends coded messages by radio without a physical telegraph wire. It established practical long-distance radio messaging before voice broadcasting.

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