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. (Check out the image on the left) However radars don’t use sound as a signal. Instead they use certain kinds of electromagnetic waves called radio waves and microwaves. This is where the name RADAR comes from (Radio Detection And Ranging). Sound isused as a signal to detect objectsin devices called SONAR (Sound Navigation Ranging). Another type of signal used that is relatively new is laser light that is used in devices called LIDAR (you guessed it…Light Detection And Ranging). HISTORY OF RADAR The history of radar starts with experiments by Heinrich Hertz in the late 19th century that showed that radio waves were reflected by metallic objects. The name radar comes from the acronym RADAR, coined in 1940 by the U.S. Navy .Several inventors, scientists, and engineers contributed to the development of radar .The first touse radio waves to detect “the presence of distant metallic objects” was Christian Hülsmeyer.Before the Second World War developments by the British, the Germans, the French, the Soviets and the Americans led to the modern version of radar. World War II saw more rapid developments in radar technology. Both the British and the Germans were engaged in a race to produce larger and more sophisticated radars. However, the Germans were not able to fully harness it. It was the British that were able to utilize it more effectively. TARGET DETECTION • Radars create an electromagnetic (EM) pulse that isfocused by an antenna, and then transmitted through the atmosphere (Figure A). • Objects in the path of the transmitted EM pulse, called “targets” or “echoes,” scatter most of the energy, but some willbe reflected back toward the radar (Figure B)
Posted on: Wed, 04 Sep 2013 03:24:05 +0000
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