Have you noticed that a lot of technological innovations we enjoy today in various fields were initially developed strictly for military operations before they Gradually made thier way into various civilian operation.
My topic today is about one of such innovations—Radars.
Radar was created secretly by several nations before world war II to track and detect enemy aircrafts and ships so they could initiate surprise and successful attacks. Over the years radar has evolved due to technological advancement and are used by developed countries in antimissile systems to accurately detect guided missiles amongst it other numerous modern usage.
The utilization of radar has increased immensely and have spread to various civilian fields outside the military. Radars are used as navigation tools by ships, and aircrafts. Major airports around the world make use radar technology to track planes on ground and in the air. The very large radar scanning dish in airports helps in easier traffic control and smooth landing of planes on the runways in the airport. With this in place the air traffic controllers can direct planes movement effortlessly regardless of the weather.
Radar is also a superb tool used by NASA to map the earth or other planets, radars play a major role in outer space surveillance and they effectively help to track satellites and space debris in docking and maneuvering. In developed countries policemen detect the speed of moving motorists using a device called the radar speed gun to determine if they exceed specified speed limits.
Weather forecasters make use of radar to track storms, hurricanes and tornadoes. Forecasters can determine the speed of incoming storms and how long it would take to hit some locations by simply firing a radar beam into the cloud.Archeologists and geologist also make use of ground penetrating radar to determine where historical artifacts are buried and to check the composition of a particular area of land before excavation.
Let’s take a closer look at Radars.
Radar simply means Radio detection and ranging, just as the name implies radar are unique and can be utilized for different purposes. Radars are basically used to achieve one of these three things:
Radar are used to detect the location of objects, although radars are used more often to detect objects in motion such as ships and airplanes but they can also be effective in ascertaining the position of stationary objects such as underground items. radars can also identify the kind of approaching vessel. for example, some radar sets can accurately determine the kind of aircraft that is advancing closer.
Secondly radars could be used to determine the speed of an object. This is another important feature of a radar; a typical example is a policeman using radar guns to monitor the speed of moving cars.
Lastly radars are effective tools used for mapping. For instance, synthetic Aperture Radar is used by orbiting satellite for mapping of the surface of planets and moons.
These three activities listed are achieved using echo and Doppler shift concepts.
Echo is a very familiar scenario that occurs all the time, I remember as kids we would locate a well and shout really loud into the well, the sound travels down the well then we hear the echo of our voice after a while. This happens because Some of the waves would get reflected by the water at the bottom of the well and they travel back so we could hear. The time taken for the echo to travel back for us to hear is dependent on the distance between the surface that created the echo and where we were standing. Measuring the time taken by the echo, the depth of the well can easily be calculated since we know the speed of sound.
Likewise, Doppler shift is something we experience several times during the day without realizing, this takes place when sound is reflected off a moving object or when sound is generated by a moving object. When a car is moving and its horn is blaring, as the car gets closer to an individual, a higher tone of the horn that’s blaring would be heard by the individual but as soon as the car speeds past the individual the tone of the horn becomes lower. All along it’s the same sound being made by the horn but the changes the individual hears is as a result of Doppler shift. In extreme cases Doppler shifts could create sonic booms.
These two concepts of echo and Doppler shift can be utilized together effectively. For instance, a car is speeding to my direction and I decide to send a loud sound to it. As usual echo would occur and some sounds would bounce back, however the sound wave would be compressed due to the fact that the car is moving towards me. Consequently, the generated echo would generate a much higher pitch than the initial sound I sent. Measuring this pitch would reveal the car’s speed. Hence Doppler shift of an Echo can effectively determine the speed of a moving object.
Regardless of where radars are used or what they are used for, typically radars would require some similar components such as a component to produce radio waves, a component to emit the radio waves produced into space and a component to receive the radio waves and a means of showing the result to the operator for speedy response.
Now let’s take a typical radar set designed to detect approaching airplane in flight as an example.
Magnetrons are responsible for generating radio waves. Magnetrons produce microwaves just like the ones generated by the usual microwave oven, however in the case of a radar the waves generated are very powerful and larger because they are required to travel several miles. Radars make use of radio waves that have a range of a few centimeters to a meter and they travel at the same speed of light waves. After the generation of the high intensity burst of radio waves by the magnetron, an antenna hurls them into the air. At this point This antenna functions as a transmitter and to ensure they can detect movement over a vast region they are built to rotate and they are curved such that the waves would be concentrated into a precise narrow beam. So this radio waves continue to travel until they hit an obstacle, then some waves bounce back and travel towards the antenna (it serves as a receiver at this point) as reflected waves at the speed of light. Once it hits the antenna it triggers the alarm to alert the operators.
The antenna also acts as the receiver in a radar system, so it transmits radio waves and also listens for any reflection before transmitting again after a few seconds. Once there is a reflection the reflected waves are processed by a computer in the plane that filters out insignificant information and effectively calculates the time it took the echo to arrive back and it also takes into consideration the Doppler shift of the echo. Using a high speed clock the distance of the approaching airplane can be calculated accurately and by using some sophisticated signal processing equipment the radar can accurately ascertain the speed of the airplane by measuring the Doppler shift. Then the relevant information is displayed on a screen so the operator monitoring can have instant access to the information and take suitable actions.
There is a duplexer that helps the antenna to facilitate its swapping from being a transmitter to being a receiver, because while the antenna is performing transmission it cannot receive. After getting this information, the operator monitoring can see and ascertain the speed at which the plane or ship is approaching, their location as well as their direction. The operators are highly trained to use this information effectively because any mistake would be costly and would lead to loss of lives.
Technology is so interesting, you might wonder If a military plane has an effective radar system to detect approaching enemy plane, most likely the enemy also has a sophisticated radar system to also detect the military plane. Several countermeasure had to be put in place to hide airplanes from being detected by enemy’s radar to ensure their safety.
Stealth technology was invented to tackle this problem by absorbing or scattering the radio waves. So when Stealth airplanes travels they can track their enemies and still escape being detected by enemy radar system. This is such a superb technique because the whole plane would be displayed on the enemy’s radar as a really small energy that is insignificant. But of course with the advancement in technology Quantum radars are being developed to detect this stealth aircraft.
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