RADIO

hi guys,my this posting is on a device which is very often used by all of us....radio।

INTRODUCTION:
The principle of radio is electromagnetic waves। Radio, system of communication employing electromagnetic waves propagated through space। Because of their varying characteristics, radio waves of different lengths are employed for different purposes and are usually identified by their frequency।
The shortest waves have the highest frequency, or number of cycles per second; the longest waves have the lowest frequency, or fewest cycles per second। In honor of the German radio pioneer Heinrich Hertz, his name has been given to the cycle per second (hertz, Hz); 1 kilohertz (kHz) is 1000 cycles per sec, 1 megahertz (MHz) is 1 million cycles per sec, and 1 gigahertz (GHz) is 1 billion cycles per sec। Radio waves range from a few kilohertz to several gigahertz। Waves of visible light are much shorter। In a vacuum, all electromagnetic waves travel at a uniform speed of about 300,000 km per second।


PARTS OF RADIO:

A)TRANSMITTER

i)oscillators
ii)modulations
iii)antenas
Essential components of a radio transmitter include an oscillation generator for converting commercial electric power into oscillations of a predetermined radio frequency; amplifiers for increasing the intensity of these oscillations while retaining the desired frequency; and a transducer for converting the information to be transmitted into a varying electrical voltage proportional to each successive instantaneous intensity. For sound transmission a microphone is the transducer; for picture transmission the transducer is a photoelectric device.


B)RECEIVERS

i)amplifiers
ii)high fidelity systems
iii)distoration
iv)noise
v)power supply

The essential components of a radio receiver are an antenna for receiving the electromagnetic waves and converting them into electrical oscillations; amplifiers for increasing the intensity of these oscillations; detection equipment for demodulating; a speaker for converting the impulses into sound waves audible by the human ear. In most radio receivers, oscillators to generate radio-frequency waves that can be “mixed” with the incoming waves.