What is Airport Surveillance Radar (ASR)?

Do you know about Airport Radar System or Airport Surveillance Radar (ASR), types of radar system, display systems, how it works, etc. Let us study through this article.

Airport Surveillance Radar (ASR)

It is an integrated primary and secondary radar system that has been deployed at terminal air traffic control sites. ASR is also known as Terminal Area Radar (TAR). Basically, it is a radar system used at airports to detect and display the position of aircraft in the terminal area, the airspace around the airports. Let us tell you that the primary radar consists of a large rotating parabolic antenna dish that sweeps a vertical fan-shaped beam of microwaves around the airspace surrounding the airport. The position of the aircraft is detected with the help of microwaves reflected back to the antenna from the surface of the aircraft. The second surveillance radar has a second rotating antenna which is mounted on the primary antenna and interrogates the transponders of the aircraft, which transmits a radio signal back containing the aircraft's identification and altitude. This is displayed on the screen of the radar next to the return from the primary radar.

Now let us study about Radar.

RADAR word stands for Radio Detection and Ranging. Do you know that pilots can't see where they are going, so they use the technique radar to help them? This system sends and receives radio waves.

How Radar works?

Source: www.ourairports.biz.com
The radar includes Antenna, Duplexer, Transmitter, Phase-Lock Loop (PLL), Receiver and Processing. The radio waves used by Radar are produced by equipment known as magnetron. Radio waves are similar to light waves and they travel at the same speed but their waves are much longer and have much lower frequencies. No doubt both light waves and radio waves are a part of electromagnetic spectrum that is they are made up of fluctuating patterns of electrical and magnetic energy coming through the air.

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Source: www.oarnorthwest.com
When radio waves are generated, an antenna, working as a transmitter hurls them into the air in front of it. The antenna doubles up as a radar receiver as well as a transmitter. It also transmits radio waves for a few thousandths of a second, and then it listens the reflections for up to several seconds before transmitting again. Any radio wave that is reflected picked up by the antenna and are directed into a piece of electronic equipment that processes and displays them in a meaningful form on a television like screen which is watched all the time by a human operator. Also, the receiving equipment filters out useless reflections from the ground, buildings and so on. It displays only significant reflections on the screen itself. Do you know that by using radar, an operator can see any nearby ships or planes like where they are, how quickly they are travelling etc. One more important equipment is duplexer which makes the antenna swap back and forth between transmitter and a receiver. While the antenna is transmitting, it cannot receive and vice versa.

Applications of Radar

Source: www.bbc.com

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1. Military applications:
In air defense it is used for target detection, target recognition and directing the weapon to the tracked targets, to guide the weapon in the missile system and to identify enemy locations in the map.

2. Air Traffic Control: to control air traffic near airports. Also, the Air Surveillance Radar is used to detect and display the position of the aircraft in the airport terminals, by using Precision Approach Radar it guide the aircraft to land in bad weather and to scan the surface of airport for aircraft and ground vehicle positions.

3. Remote Sensing: For observing weather or observing planetary positions and monitoring sea ice to ensure smooth route for ships.

4. Ground Traffic Control: Radar technique is used by traffic police also to determine vehicle speed, controlling the movement of vehicles by giving warnings about the presence of other vehicles or any type of obstacles behind them.

5. Space: For safe landing on moon to guide the space vehicle, to observe the planetary systems, to detect and track satellites and to monitor the meteors.

Can radar waves be bypassed?

The technique to avoid radar waves or to bypass the waves of radar is called stealth technology. Its main goal is to make an airplane invisible to radar. It creates invisibility by two different methods:

1. It depends upon the shape of the airplane. It is shaped like that any radar signals if reflects are reflected away from the equipment of the radar.

2. The airplanes can be covered in materials that absorbs radar signals.

The conventional shape of the aircraft is round and in this some of the radar signal gets reflected back. On the other hand, a stealth aircraft is made up of completely flat surface and with very sharp edges. So, when a radar signal hits a stealth plane, the signal reflects away at an angle. Also, surface of the aircraft is made like that they absorb the energy of radar. So, it is said that a stealth aircraft can have a radar signature of a small bird rather than an airplane.

So, now you may have understood about the Radar Surveillance System or Radar technology, how it works, its applications etc.

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