What is RADAR Technology?

RADAR stands for Radio Detection and Ranging System. It is basically an electromagnetic system used to detect the location and distance of an object from the point where the RADAR is placed. It works by radiating energy into space and monitoring the echo or reflected signal from the objects. It operates in the UHF and microwave range.

A Basic Idea of RADAR

The RADAR system generally consists of a transmitter which produces an electromagnetic signal which is radiated into space by an antenna. When this signal strikes any object, it gets reflected or reradiated in many directions. This reflected or echo signal is received by the radar antenna which delivers it to the receiver, where it is processed to determine the geographical statistics of the object. The range is determined by the calculating the time taken by the signal to travel from the RADAR to the target and back. The target’s location is measured in angle, from the direction of maximum amplitude echo signal, the antenna points to. To measure range and location of moving objects, Doppler Effect is used.

Who invented radar?

 Radar can be traced back to a device called a Telemobiloskop, invented in 1904 by German electrical engineer Christian Hülsmeyer (1881–1957). After hearing about a tragic collision between two ships, he figured out a way to use radio waves to help them see one another when the visibility was poor.

 Although many scientists contributed to the development of radar, best known among them was a Scottish physicist named Robert Watson-Watt (1892–1973). During World War I, Watson-Watt went to work for Britain's Meteorological Office (the country's main weather forecasting organization) to help them use radio waves to detect approaching storms.

 In the run up to World War II, Watson-Watt and his assistant Arnold Wilkins realized they could use the technology they were developing to detect approaching enemy aircraft. Once they'd proved the basic equipment could work, they constructed an elaborate network of ground-based radar detectors around the south and east of the British coastline. During the war, Britain's radar defenses (known as Chain Home) gave it a huge advantage over the German air force and played an important part in the ultimate allied victory. A similar system was developed at the same time in the United States and even managed to detect the approach of Japanese airplanes over Pearl Harbor, in Hawaii, in December 1941—though no-one figured out the significance of so many approaching planes until it was too late.

What is radar used for?

Radar is still most familiar as a military technology. Radar antennas mounted at airports or other ground stations can be used to detect approaching enemy airplanes or missiles, for example. The United States has a very elaborate Ballistic Missile Early Warning System (BMEWS) to detect incoming missiles, with three major radar detector stations in Clear in Alaska, Thule in Greenland, and Fylingdales Moor in England. It's not just the military who use radar, however. Most civilian airplanes and larger boats and ships now have radar too as a general aid to navigation. Every major airport has a huge radar scanning dish to help air traffic controllers guide planes in and out, whatever the weather. Next time you head for an airport, look out for the rotating radar dish mounted on or near the control tower.

You may have seen police officers using radar guns by the roadside to detect people who are driving too fast. These are based on a slightly different technology called Doppler radar. You've probably noticed that a fire engine's siren seems to drop in pitch as it screams past. As the engine drives toward you, the sound waves from its siren are effectively squeezed into a shorter distance, so they have a shorter wavelength and a higher frequency—which we hear as a higher pitch. When the engine drives away from you, it works the opposite way—making the sound waves longer in wavelength, lower in frequency, and lower in pitch. So you hear quite a noticeable drop in the siren's pitch at the exact moment when it passes by. This is called the Doppler effect.

The same science is at work in a radar speed gun. When a police officer fires a radar beam at your car, the metal bodywork reflects the beam straight back. But the faster your car is traveling, the more it will change the frequency of the radio waves in the beam. Sensitive electronic equipment in the radar gun uses this information to calculate how fast your car is going.

Radar has many scientific uses. Doppler radar is also used in weather forecasting to figure out how fast storms are moving and when they are likely to arrive in particular towns and cities. Effectively, the weather forecasters fire out radar beams into clouds and use the reflected beams to measure how quickly the rain is traveling and how fast it's falling. Scientists use a form of visible radar called lidar (light detection and ranging) to measure air pollution with lasers. Archeologists and geologists point radar down into the ground to study the composition of the Earth and find buried deposits of historical interest.

Here's a summary of how radar works:

1.Magnetron generates high-frequency radio waves.

2.Duplexer switches magnetron through to antenna.

3.Antenna acts as transmitter, sending narrow beam of radio waves through the air.

4.Radio waves hit enemy airplane and reflect back.

5.Antenna picks up reflected waves during a break between transmissions. Note that the same antenna acts as both transmitter and receiver, alternately sending out radio waves and receiving them.

6.Duplexer switches antenna through to receiver unit.

7.Computer in receiver unit processes reflected waves and draws them on a TV screen.

8.Enemy plane shows up on TV radar display with any other nearby targets.