What Is Radar :-Radar stands for Radio Detection And Ranging . As by the full form of we got some idea about radar that it is work for detection of objects . Now in detail radar can be defined as a system which is used to detect the object and to determine the range , angle and velocity of object by radio waves . It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain.
Parts Of Radar :-
TransmitterThe radar transmitter produces the short duration high-power rf pulses of energy that are into space by the antenna.
DuplexerThe duplexer alternately switches the antenna between the transmitter and receiver so that only one antenna need be used. This switching is necessary because the high-power pulses of the transmitter would destroy the receiver if energy were allowed to enter the receiver.
ReceiverThe receivers amplify and demodulate the received RF-signals. The receiver provides video signals on the output.
Radar AntennaThe Antenna transfers the transmitter energy to signals in space with the required distribution and efficiency. This process is applied in an identical way on reception.
IndicatorThe indicator should present to the observer a continuous, easily understandable, graphic picture of the relative position of radar targets.
The radar screen (in this case a PPI-scope) displays the produced from the echo signals bright blibs. The longer the pulses were delayed by the runtime, the further away from the center of this radar scope they are displayed. The direction of the deflection on this screen is that in which the antenna is currently pointing.
DisplayThe receiver sends the output to display, which shows the analyzed signal in an easily understandable user friendly manner.
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How Radar Works :-The radio waves used by radar are produced by a piece of equipment called a magnetron. Radio waves are similar to light waves: they travel at the same speed—but their waves are much longer and have much lower frequencies. Light waves have wavelengths of about 500 nanometers (500 billionths of a meter, which is about 100–200 times thinner than a humaBoth light and radio waves are part of the electromagnetic spectrum, which means they're made up of fluctuating patterns of electrical and magnetic energy zapping through the air. The waves a magnetron produces are actually microwaves, similar to the ones generated by a microwave oven. The difference is that the magnetron in a radar has to send the waves many miles, instead of just a few inches, so it is much larger and more powerful.
Once the radio waves have been generated, an antenna, working as a transmitter, hurls them into the air in front of it. The antenna is usually curved so it focuses the waves into a precise, narrow beam, but radar antennas also typically rotate so they can detect movements over a large area. The radio waves travel outward from the antenna at the speed of light (186,000 miles or 300,000 km per second) and keep going until they hit something. Then some of them bounce back toward the antenna in a beam of reflected radio waves also traveling at the speed of light. The speed of the waves is crucially important. If an enemy jet plane is approaching at over 3,000 km/h (2,000 mph), the radar beam needs to travel much faster than this to reach the plane, return to the transmitter, and trigger the alarm in time. That's no problem, because radio waves (and light) travel fast enough to go seven times around the world in a second! If an enemy plane is 160 km (100 miles) away, a radar beam can travel that distance and back in less than a thousandth of a second.
The antenna doubles up as a radar receiver as well as a transmitter. In fact, it alternates between the two jobs. Typically it transmits radio waves for a few thousandths of a second, then it listens for the reflections for anything up to several seconds before transmitting again. Any reflected radio waves picked up by the antenna are directed into a piece of electronic equipment that processes and displays them in a meaningful form on a television-like screen, watched all the time by a human operator. The receiving equipment filters out useless reflections from the ground, buildings, and so on, displaying only significant reflections on the screen itself. Using radar, an operator can see any nearby ships or planes, where they are, how quickly they're traveling, and where they're heading. Watching a radar screen is a bit like playing a video game—except that the spots on the screen represent real airplanes and ships and the slightest mistake could cost many people's lives.
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There's one more important piece of equipment in the radar apparatus. It's called a duplexer and it makes the antenna swap back and forth between being a transmitter and a receiver. While the antenna is transmitting, it cannot receive—and vice-versa. Take a look at the diagram in the box below to see how all these parts of the radar system fit together.
Applications Of Radar :-
Military Applications:The RADAR has 3 major applications in Military:
- In air defense it is used for target detection, target recognition and weapon control (directing the weapon to the tracked targets).
- In missile system to guide the weapon.
- Identifying enemy locations in map.
Air Traffic Control:The RADAR has 3 major applications in Air Traffic control:
◆ To control air traffic near airports. The Air Surveillance RADAR is used to detect and display the aircraft’s position in the airport terminals.
◆ To guide the aircraft to land in bad weather using Precision Approach RADAR .
◆ To scan the airport surface for aircraft and ground vehicle positions .