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In transmission, a radio transmitter supplies an electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception , an antenna intercepts some of the power of a radio wave in order to produce an electric current at its terminals, that is applied to a receiver ...
A radio-frequency power amplifier (RF power amplifier) is a type of electronic amplifier that converts a low-power radio-frequency (RF) signal into a higher-power signal. [1] Typically, RF power amplifiers are used in the final stage of a radio transmitter , their output driving the antenna .
A radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. Radio waves are electromagnetic waves with frequencies between about 30 Hz and 300 GHz. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the ...
The term radio receiver is understood in this article to mean any device which is intended to receive a radio signal in order to generate useful information from the signal, most notably a recreation of the so-called baseband signal (such as audio) which modulated the radio signal at the time of transmission in a communications or broadcast system.
Common circuit diagram symbols (US ANSI symbols) An electronic symbol is a pictogram used to represent various electrical and electronic devices or functions, such as wires, batteries, resistors, and transistors, in a schematic diagram of an electrical or electronic circuit. These symbols are largely standardized internationally today, but may ...
The regenerative receiver, invented by Edwin Armstrong [118] in 1913 when he was a 23-year-old college student, [119] was used very widely until the late 1920s particularly by hobbyists who could only afford a single-tube radio. Today transistor versions of the circuit are still used in a few inexpensive applications like walkie-talkies.
An early 2000s transistor radio (Sony Walkman SRF-S84 transistor radio, released 2001, shown without earphones) Rock 'n roll music became popular at the same time as transistor radios. Parents found that purchasing a small transistor radio was a way for children to listen to their music without using the family tube radio.
Block diagram of a crystal radio receiver Circuit diagram of a simple crystal radio. A crystal radio can be thought of as a radio receiver reduced to its essentials. [3] [39] It consists of at least these components: [22] [40] [41] An antenna in which electric currents are induced by electromagnetic radiation.