From ArticleWorld

The radio is a wireless system of communication which puts to use electromagnetic waves of radio frequencies (frequencies below that of light) which are transmitted through space. The type of frequency employed depends on the type of application in which communication is desired. Radio waves are thus created when a charged object accelerates with a certain frequency that lies in the radio frequency section of the electromagnetic spectrum. The acceleration can also be caused by an alternating current in an antenna. The frequency of radio waves can be anything in between a few kilohertz to several gigahertz. Sources of error in radio communication can be storms and electrical disturbances.

Application of radio Radio waves have a wide range of applications. The primary application of radio waves is in radio and television broadcasting. This may require the use of satellites for international transmission. The military uses radio technology extensively during both peacetime and wartime operations. Radio links establish communication during emergency rescue operations in the event of natural calamities. Links between commanders and frontline troops during war, search and rescue operations, as well as intelligence-gathering missions require the use of radio technology. Radar systems, used by the civil aviation authorities, navy and air force make use of radio systems. Space communication is also done using this wonderful technology. A historic example of the radio being used in such an application is of Neil Armstrong, who uttered his famous words ‘one small step for man…’ after having set foot on the moon. His voice was beamed live across 385,000 km to the earth.

Propagation of radio waves in radio communication

Radio systems basically require a transmitter and a receiver. A transmitter consists of an oscillation generator which converts electrical power into oscillations of a predetermined radio frequency. Amplifiers increase the intensity of these oscillations. The instantaneous frequency of the carrier wave is modulated according to the signal to be transmitted. Transducers are present to convert sound energy into electrical signals for this purpose.

Broadcasting stations use carefully controlled quartz-crystal oscillators. Antennas are required to transmit signals.

An antenna is an important part of a radio receiver as well. Radio waves are converted into electrical oscillations which are amplified. Detection equipment demodulates the signals and a speaker / picture tube converts them into audible/visible signals.

History and development of the radio

British physicist James Maxwell’s theory of electromagnetic waves is considered to be the starting point in the history of the radio. The Italian electrical engineer Guglielmo Marconi is credited with the invention of the first practical radio transmission and reception system. This happened in 1894. Soon after, he opened the Wireless Telegraph and Signal Company Limited. The radio age had emerged, when signals began to be transmitted across the Atlantic. The radio today is not just an entertainment medium; it is the sole means by which today’s Information Age has taken shape.