Radio is the receiver of radio broadcasting. The weak signal of high-frequency modulation input by the receiving antenna is restored to an audio signal after amplification, frequency conversion and detection. According to different needs, the radio can be combined with different components and circuit modes. Early radios used electronic tubes. Now transistors and integrated circuits are widely used. A simple circuit regenerative radio uses only one crystal triode, while a complex circuit superheterodyne AM FM radio often uses a variety of integrated circuits.
Although it is more and more convenient to watch TV and listen to music, radio is still necessary for its existence, because there is no TV signal in many places. It depends on radio, because it is the most economical policy publicity tool. Through it, you can know the news outside. There are more radio stations in big cities, in taxis, at school and on the way to work. These are the world of sound! Radio also has its unique advantage, that is, a steady stream of sound! At dusk, listening to the old songs from the old radio and watching the sunset is also a great pleasure in life!