What is meant by a radar?

Radar is a system that uses waves of energy to sense objects. It can find a far away object and tell how fast is it moving .Radar is very useful because it can sense objects even at night and through thick clouds.

How radar works ?

A radar system is made up of a transmitter , a receiver , an antenna , and a display. The transmitter creates radio waves , which are invisible streams of energy.The antenna sends the waves into the air. When the waves hit an object , they reflect , or bounces back, to the antenna.

The waves then pass to the receiver , which makes sense of them. By measuring how long it takes the waves to return , the receiver can tell   how far away the object is. The receiver can tell also where a moving object is headed and at what speed. Sometimes it can tell how big the object is.The receiver sends this information to a screen, for the people to see.

antenna

screen

History

Work with radar started in the 1930s. a scottish scientist named Robert watson-watt developed a radar system in 1935.It was used to help protect Great Britain fro air attacks. During the 2nd World War[1939-1945] radar helped Britain , France and the United states deafeat Germany. Since then many improvements have been made in Radar technology.Today computers help radar  systems provide more details about distant objects.