The word ‘radar’ is an acronym for ‘radio detection and ranging’. It is, in fact, an electronic device by which one can detect and measure an invisible flying object’s distance and speed. It can work efficiently under all weather conditions such as fog, mist, smoke, snow-fall, storm, cyclone, rains etc. Due to these reasons it is used in the control-room for the guidance of aeroplanes.
The radar works on the principle of ‘echo’. The sound waves reflected by some obstacle produce an echo. Similarly, radio waves which are electromagnetic in nature also get reflected when they encounter some obstacle in their path. This property of radio waves was discovered by scientists in 1930. Using this property, in 1935 five radar centres was established in America. Major developments in the field of radars took place during the Second World War. These rendered a great help in detecting the enemy bombers. Since then, many kinds of radar have been developed for peaceful uses also. Now, there are radars which help in controlling and guiding the path of unmanned space crafts. Radars giving information relating to weather are also available.
Do you know how radar works? Radars make use of radio-waves, similar to those used in radio broadcasting. However, the radio-waves used in radar have higher frequencies. They are called micro-waves. The speed of these waves is equal to that of light i.e. (186000 miles) per second. The radar centre has a transmitter which sends out radio waves with the help of an antenna towards the object. It also has a receiver which receives the radio waves reflected by the object. This receiver has a screen which shows the object’s position in the sky.
The time taken by the radio-waves in going from the transmitter to the object and in coming back to the receiver is recorded by radar. By multiplying this time with the velocity of light we get twice the distance between the radar and the object. This is how the distance of the object is determined. The radar has automatic instruments which perform all these functions. Initially, radars used to be very big in size, but now there are ones which are even smaller than our palms.
