More than 20 years later, American radio experts Mei Lan, Taylor and others found that radio waves can be reflected by airplanes. The US Naval Engineering Bureau attached great importance to this discovery and immediately formulated a research plan of "detecting enemy planes and enemy ships by radio". If this plan can be realized, then the invention patent of "radar" will belong to these two American experts. However, they were only one step away from success and missed it.
Later, in 1934, American scientist Peggy observed the radio waves (that is, echoes) reflected by the plane. However, what he saw was the radio wave reflected from an airplane 1.6 kilometers away, which was closer to the radar that was born later.
1935 In February, British scientist Watt and his assistant found in their experiments that the radio waves they sent suddenly appeared unusual on the "echo display"-the echo displayed was not the usual white point, but a short line. So Watt exclaimed, "These are three planes!" Later, I learned that there were indeed three planes flying by. This shows that they finally detected the plane by radio echo. Subsequently, Watt designed the original radar based on this experiment. In this way, the radar officially came out. Watt named it "Radio Scout". The British government attached great importance to this important invention and gave strong support, so this new reconnaissance equipment was popularized and played an important role in the Second World War.
As can be seen from the above introduction, the secret of radar detecting targets is that after the radar sends out radio waves, it will reflect and produce echoes when it meets objects such as airplanes and missiles. According to the time of receiving the echo, the distance of the target can be calculated and the target can be displayed on the display. In fact, this is the same as the principle that people use sound (sound waves) to detect the distance of cliffs. When you climb a mountain, you want to know how far the cliff opposite is from you. The way is simple. Put your hand in front of your mouth and shout at the cliff, and you will hear the echo in a moment. You can use your watch to calculate that if there is an interval of 5 seconds from the beginning of shouting to hearing the "echo", the speed of sound propagation is about 340 meters per second. In this way, the sound * * * walked in 5 seconds 1700 meters. This is the round-trip distance of sound, and half is the actual distance from the cliff to you, which is 850 meters.
The radar antennas you see in movies or on TV are some like cauldrons, some like cobwebs, some like rows of fishbones, some like tiles … all kinds. These antennas are the "platforms" for radar to transmit radio waves and receive reflected echoes. Only when directional radio waves are emitted from these antennas and reflected by targets can people see planes, missiles and other targets hundreds or thousands of kilometers away, so radar is called "clairvoyance" on the battlefield.