4. •Radar is an object detection system which uses radio waves to determine the
range, altitude, direction, or speed of objects.
•It can be used to detect aircraft, ships, spacecraft, guided missiles, motor
vehicles, weather informations, and terrain.
5. •Radar was secretly developed by several nations before and during World
War II.
•As early as 1886, German physicist Heinrich Hertz showed that radio waves
could be reflected from solid objects.
•By using these the German inventor Christian Hulsmeyer was the first to use
radio waves to detect the presence of distant metallic objects.
•Before the Second World War, researchers in France, Germany, Italy, Japan,
the Netherlands, the Soviet Union, the United Kingdom, and the United
States, independently and in great secrecy, developed technologies that led to
the modern version of radar.
6. •The basic idea behind radar is very simple: a signal is transmitted,
it bounces off an object and it is later received by some type of
receiver. This is like the type of thing that happens when sound echo's
off a wall.
7. •A basic radar system is spilt up into a transmitter, switch, antenna, receiver,
data recorder, processor and some sort of output display.
•Everything starts with the transmitter as it transmits a high power pulse to
a switch which then directs the pulse to be transmitted out an antenna.
•The radar signals that are reflected back towards the transmitter and are
received by the receiver.
•Time taken by the wave to reach the receiver is measured and then all this
information is processed to determine the distance of the object.
•And at last the processed information is displayed in some sort of output
display like monitor.
8. •To determine the range of a distant object that reflected a radar signal, the
receiver must record the time when the signal was received and compare it to
when that signal was transmitted. This time is the time taken for the radio wave
to propagate to the object and back to the antenna.
•A simple equation is used to determine the distance. That is
V=d/t
Thus d=V*t
NOTE :
Here the final result should be divided by 2 as wave travels double distance.
Once when it is transmitted and second when it is strike the antenna.
•Also by using this formula we can measure speed if we know distance and time.
9. •Radar is something that is in use all around us, although it is normally
invisible.
•Air traffic control uses radar to track planes both on the ground and in the
air, and also to guide planes in for smooth landings.
•Police use radar to detect the speed of passing motorists.
•The military uses it to detect the enemy and to guide weapons.
•Meteorologists use radar to track storms, hurricanes and tornadoes.
•You even see a form of radar at many grocery stores when the doors open
automatically! Obviously, radar is an extremely useful technology.
