RADAR
RADAR,an acronym for RAdio Detection And Ranging, is based on German scientist Heinrich Hertz's 1880s discovery that a beam of radio energy that strikes an object of sufficient density will be reflected by it. If that reflected energy is then captured by a receiver at the beam's origin it can be analyzed. Another German scientist, Christian Hulsmeyer, patented the first radio echo device in 1904. Because radio energy travels at a constant speed (the speed of light) the length of time between sending and receiving the energy can thus be used to calculate the object's distance. The direction from which the energy is received can be used to determine the object's bearing. Combining distance and bearing indicates the object's location on/above the surface of the Earth. Modern radars belong to one of two general types. Pulse radars emit a short, intense burst of radio energy, while continuousâwave radars emit a steady signal. The latter, often called Doppler...
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