RADIO

This article is about radio as a technology. For other uses, including radio broadcasting as an art form, see Radio (disambiguation).

Transducing information such as sound into an electronic signal, which is then sent as an electromagnetic radio wave from a transmitter. A receiver intercepts the radio wave and extracts the information-bearing electronic signal, which is converted back using another transducer such as a speaker.

Radio is the wireless transmission of signals through free space by electromagnetic radiation of a frequency significantly below that ofvisible light, in the radio frequency range, from about 30 kHz to 300 GHz.^[1] These waves are called radio waves. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space.

Information, such as sound, is carried by systematically changing (modulating) some property of the radiated waves, such as theiramplitude, frequency, phase, or pulse width. When radio waves strike an electrical conductor, the oscillating fields induce analternating current in the conductor. The information in the waves can be extracted and transformed back into its original form.