Anecdote of radar invention
During the First World War, military aircraft appeared, and some countries encountered great difficulties in resisting its attacks. To this end, some scientists began to develop an instrument for finding planes at a long distance, which was later radar.
However, the invention of radar can be traced back to19th century. 1887, when the German scientist Hertz confirmed the existence of electromagnetic waves, he found that electromagnetic waves would reflect back when they met metal objects during propagation, just like reflecting light with a mirror. This is essentially the working principle of radar. However, at that time, Hertz did not think of using this principle to carry out radio communication experiments. At that time, the communication was suddenly interrupted and returned to normal after a few minutes. This phenomenon has appeared several times in a row. At first, he thought there was something wrong with the machine. After inspection, everything is normal. So, he observed the external situation and found a ship passing between two warships. After the ship passed by, the communication between the two ships returned to normal. With his keen sense of smell, popov immediately realized that it was the ship that blocked the radio waves when passing between two ships. From this, he thought that if radio communication equipment was installed on the sea route, the sea target could be detected by electric waves. But unfortunately, he didn't put this idea into practice. Until 1922, American scientists installed electromagnetic wave transmitters and receivers on both sides of the sea channel according to popov's idea. When a ship passes by, it can be detected by radio waves immediately. This is equivalent to setting up an invisible warning line at sea. However, this equipment is still not a radar in a strict sense.
1935, Watson Watt, a famous British physicist and director of the Radio Research Office of the National Institute of Physics, invented a device that can not only emit radio waves, but also receive reflected waves, and can detect the movements of aircraft from a distance. This is the first radar in the world. This kind of radar can emit 1.5 cm microwave, because microwave has better directivity than medium wave and short wave, and the energy reflected back after encountering obstacles is large, so it has good performance in detecting aircraft flying in the air. For safety and convenience, this kind of radar was called CH system at that time. After several improvements, the CH system was officially installed near the Thames estuary on 1938. This 200-kilometer radar network posed a great threat to Hitler in World War II. Subsequently, the British navy installed radars on warships, and these radars also played an important role in naval battles. Radar is not only used in military affairs, but also can be used to detect the weather and find tombs, caves and ant nests 20 meters underground. With the progress of science and technology, the application of radar is more and more extensive.
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