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Terrestrial
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The Joy
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| This is the Arecibo Observatory in Puerto Rico operated by Cornell University. It is one of the most powerful radar-radio telescopes and the largest single unit telescope in the world. To find out more go to www.naic.edu. |
| Radar, which stands for RAdio Detection And Ranging, is a very effective tool to detect the presence of objects and basically just transmit information. Without a doubt it was a technological break-though when it was accidentally discovered that radar was sensitive enough to detect precipitation and snow during World War II. Since then the scientific community has taken great advantage of the potential that this tool provides. Radar can be used to detect asteroids, provide communication to spacecraft, aircraft or any type of craft, detect precipitation for weather forecasts, create images of surface topography, detect underground beds, give cops an excuse to pull you over when they have nothing better to do and many many others. |
Types of Radar Simple Pulsed Radar: This is a very simple type of radar that is used in ground penetrating radar and imaging radars. In this system, the transmitter transmits short pulses of radio or microwave signals. This is a very useful radar for finding objects. Continuous Wave Radar: This type of radar system transmits a continuous wave rather than short pulses and analyzes the change in frequency of the returned signal. This is a good type of radar to determine the velocity of objects. Synthetic Aperture Radar (SAR): To increase the resolution of a radar image, a very large antenna with a narrow beam width is necessary. Since very large antennas can sometimes be impractical, synthetic aperture radar was developed to use a small radar antenna like it was a large one. To accomplish this SAR repeatedly takes measurements from several positions. These measurements are then processed like they were taken from a single large antenna. Phased Array Radar: This radar uses many very small antennas that can be rotated to comprise a very large antenna that can change it's beam direction very quickly. Secondary Radar: This kind of radar uses coded signals to be transmitted and received to allow communication between targets. This type of radar is used in air traffic control. Ground-Penetrating Radar: |
