Radios operate by transmitting signals (or radio waves) invisibly, over the air. Oscillating electromagnetic fields produces radio waves. The technology to produce and receive radio waves is fundamentally very basic and if you wanted, you could make your own radio transmitter for just pennies.
We are so reliant on radio communication in our everyday lives; it is hard to imagine life without it. Radio communication is used in many types of technology - television broadcasts, AM /FM radio, even mobile phones, to name but a few. Wireless Internet, which is becoming increasingly popular, also uses radio waves. Things like navigation and communication satellites wouldn't be possible without the use of radio waves.
When
most of us think of radio we think about it in the context of broadcast media
(public radio stations). In this
context sound is carried in waveform, on a specific frequency, across the
airwaves and is received by radio receivers ,that receive and amplify those sound
signals to a level audible to the human ear. Traditionally, radio was
transmitted by analog signal on either the FM or AM band of frequencies. Whilst
analog radio is still very popular, many broadcasters today also offer their
programs in digital format. DAB is
the most common standard for digital radio transmission.