Sandeep Kumar

A blog By Sandeep kumar

How Does Radar Work?

Posted by Sandeep Kumar on July 29, 2010

The concept of radar was introduced in 1902, but radar systems were implemented in late 1930s. The concept includes the radio waves which were used to detect objects. Many countries aided the inventors in their research and were successful in the development of a rudimentary warning system which could detect moving objects. During World War II, this system was used to guard the coastline of England against hostile German aircraft. Using high frequency radio waves, the system could detect enemy German planes during World War II and calculate the distance between the system and the planes. This application of the system lead to its being named radar, which stands for `radio detection and ranging’.

It might be confusing to understand the principle of the radar, but it can be explained with the help of a very simple experiment. We need two additional instruments: a “super hearing” device and an accurate stopwatch. Now imagine a place where we are facing the side of a mountain at some distance. In this experiment, a person can become a basic radar unit. We just have to scream as loudly as we can and at the same time we should start the timing mechanism of a stopwatch. We stop the watch when the first echo of our voice comes back to us. Now we have the time in which the voice rolls back to us, and we know the speed of sound, so we can easily calculate the distance between us and the mountain.

The above demonstrated principle is applied to the radar, in the way it works. A burst of powerful radio beams at a high frequency is sent out by the radar set. When this radio energy bounces off a solid object, a small portion of the energy will be reflected back to the transmitter end of the radar set. To detect this small part of the reflected energy, a sensitive electronic receiver is used, which amplifies that weak signal for further processing, just like the super hearing device used in the above example. The receiver and the transmitter are mounted close to each other in a basic radar unit.

RadarThus, the same formula is used by the radar operator to calculate the distance between him and the object by calculating the time taken by a signal to bounce back and also the speed of the radio waves. Multiple feedbacks are allowed by the moving transmitter/receiver which helps it to access different points. These points are combined to detect the motion of an object and its size.

Since World War II, the underlying principle is the same for all the radar systems but a number of improvements have been made in the radar technology. Data collected from the receiver and transmitter of the radar set is used to calculate the object’s direction and speed. A duplex (a two-way communication device) is used along with a radar antenna, so that while spinning, the antenna can send out thousands of signals as well as receive them simultaneously.

Unlike shortwave radio frequencies which were used by the British inventors, modern radar systems use radio frequencies which are largely in the microwave range. This is due to the fact that microwave frequencies are very difficult to jam, while the other frequencies can be confused with the matching frequencies of radar jammers.

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