Expert: Marc Ebelini - 4/14/2010

Question
How an radar works?

Answer
Radar: Radio Detection and Ranging.  Uses the echo bouncing off objects. The same principal is used in Sonar. Sound Navigation and Ranging. Radar uses very high frequencies in the Giga hertz range. The actually frequencies depends on what it is used for. Weather radars as compared to navigational radars. Based on the speed of RF frequencies the calculations are based on 12.36 micro seconds per mile. The intensity of the reflected energy is display on a monitor whose colors or shades of a color are used to see the objects reflecting the energy. The stronger the energy the darker the shade or in later systems transferred into colors that are often seen in weather reports. Radars can either scan 360 degrees or in a small sector when used in aircraft. Some can direct the signal downward to map the ground below. The antennas produce a narrow beam to determine the precise position the echo came from to measure the time from the reflected signals. Sonar works the same except for the use of much lower frequencies. Typically 200 KHz for small water and 35 KHz for deep water. The echo time in water is 750 meters a second.
To further explain the principal, if a very narrow beam of sound was directed at an object it's distance could also be calculated by using the speed of sound in air which is 1080 feet per second so allowing for the return this would calculate a 540 feet per second. So you can see the speed of sound travels faster in water. You probably have determined how far away a lighting strike was by counting how long the sound came after the lighting bolt. Hope this answers your question