Radio Transmitter
Radio communication is the transfer of high – frequency energy from the transmitter to the receiver. Accordingly, the main components of radio communication of any kind are a transmitter and a receiver. The function of a transmitter is to generate electrical oscillations at radio frequency which is called the carrier frequency. The main components of a transmitter are an oscillator, amplifiers, and a transducer. Their functions are as follows. The oscillator of a transmitter converts electric power into oscillations of definite radio frequency. As for amplifiers, they increase the intensity of oscillations produced by the oscillator and retain the definite frequency. The transducer converts the information to be transmitted into a varying electrical voltage. In case of sound transmission a microphone serves as a transducer. And in case of picture transmission a photoelectric device serves as the transducer. Other important components of radio transmitters are the modulator and the aerial. As for modulators, they use proportional voltages for controlling the variations of oscillations intensity. And the aerial is that part of a radio system from which energy is transmitted into or received from the space (or the atmosphere). The aerial must be insulated from the ground and may occupy vertical or horizontal position. In case the transmitter aerial occupies vertical position, the receiver aerial must be also vertical and vice versa. It applies to all radio frequencies except short waves. In usual amplitude – modulated broadcasting the receiver aerial may consist of a wire wound on a core.
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