Bright Sword starts with the grenade flat.

Chapter 528 Structure of Electromagnetic Radar
After knowing that radar is a basic structure formed by the rebound of electromagnetic waves, we can naturally design radar according to this principle. Of course, this design process looks complicated and is actually full of difficulties, otherwise radar would not be called cutting-edge technology.

Of course, no matter what kind of electromagnetic wave radar it is, it is basically composed of five parts. The first part is the device that generates electromagnetic waves.

After all, if radar wants to detect targets, it needs radio waves. The tool that can excite radio waves in space in radar is the vibrator, which is actually a metal rod.

The process of electrons bouncing back and forth in a metal rod is called electrical oscillation. If there is no resistance during the rebound process, this rebound will continue. The electron flow oscillates from the left end of the metal rod to the right end and then returns from the right end to the left end. This is called an oscillation. The number of oscillations per second is called the frequency of the oscillation.

The speed of electron flow in the metal rod is extremely fast, close to the speed of light, and is constant. Therefore, the longer the metal, the longer it takes for the electron flow to oscillate back and forth, and the lower the oscillation frequency.

The distance that the electron flow travels during one oscillation is the wavelength. Obviously, the distance that the electron flow travels during this period is exactly twice the length of the metal rod. In other words, the length of the metal rod is exactly half of the wavelength. Therefore, this metal rod is often called a half-wave oscillator.

The very high-frequency electrical oscillations of the electron flow on the half-wave oscillator will excite radio waves of the same frequency in space, which will quickly leave the oscillator at the speed of light and fly away in all directions.

A half-wave oscillator is a device used by radar to emit radio waves into space. It is equivalent to a piece of wood or a flashlight bulb stirring in water, and plays the role of stirring water waves in water or emitting light waves into space. Because a half-wave oscillator can emit radio waves into space, it is sometimes called a radiator.

The second part of the radar is the transmitter that provides energy for the radio waves.

You should know that the back and forth oscillation of the electron flow in the half-wave oscillator will encounter resistance. If it is not supplied with energy to overcome various resistances, the oscillation will stop soon.

Therefore, there must be a machine in the radar that can drive the oscillation of the electron flow on the half-wave oscillator to proceed powerfully as needed. This machine is called a radar transmitter. It is the energy source of the half-wave oscillator, equivalent to the battery in a flashlight.

The radar transmitter supplies the half-wave oscillator with high-frequency electrical oscillation energy, and the half-wave oscillator excites radio waves in space. Once the radar transmitter is turned off, the half-wave oscillator stops emitting radio waves into space. Therefore, by controlling the on and off of the transmitter, the emission of radio waves into space can be controlled.

After the electromagnetic wave transmitting device and energy, there must also be a device to constrain the direction of electromagnetic wave emission, which is the third component of the radar, the radar antenna.

With a transmitter and a half-wave oscillator, radio waves can be emitted into space. However, the radio waves emitted in this way cannot be used to search and detect targets.

Because it emits radio waves in all directions in space, these waves hit the target from all directions and reflect back together, so there is no way to know which target is in which direction.

However, how to make the radar emit radio waves in only one direction? Fortunately, the light cover gave some inspiration to the radar design engineers.

You should know that if you remove the cover and reflector bowl around the flashlight bulb, the light from the bare small bulb will have no directionality. With the reflector bowl and cover, the light will only be emitted in one direction, so the reflector bowl plays the role of gathering light waves.

Therefore, the way radar transmits radio waves in a directional manner is the same as the way a flashlight focuses light, that is, it prevents the half-wave oscillator from emitting radio waves directly into space.

Instead, it emits the radio waves to a reflector that is like a big pot. The radio waves reflected from the reflector are only emitted in one direction. This kind of reflector that is like a big pot is called a parabolic reflector. Of course, the size of the reflector is determined by the requirements and is not made casually. It has a lot to do with the wavelength of the radio waves.

If the wavelength is short, the reflector can be made smaller; if the wavelength is long, the reflector must be made larger. Otherwise, the focusing effect on the radio waves will be poor. Of course, at the same wavelength, the larger the reflector, the better the focusing effect on the radio waves.

The half-wave oscillator and the pot-like reflector are combined as a whole and are called a radar antenna. This type of radar antenna is also specifically called a parabolic antenna.

For a microwave radar with a wavelength of ten centimeters, its half-wave oscillator is five centimeters long, and the diameter of its parabolic reflector must be about nine centimeters to make the emitted radio waves have sufficient directionality.

For a three-meter wavelength meter-wave radar, its half-wave oscillator is 1.5 meters long. If calculated proportionally, a large pot with a diameter of at least 270 meters is required to make the emitted radio waves have sufficient directionality.

So this is obviously not practical. Therefore, for meter-wave radar, another way must be found to achieve the directional emission of radio waves.

However, it has been found in practice that directional transmission can be achieved by arranging dozens or even hundreds of half-wave oscillators in a certain pattern, and the more half-wave oscillators there are, the better the directivity.

Under the condition of the same directional transmission performance, the shorter the radar working wavelength, the smaller the size of the radar antenna can be. However, we cannot go to the other extreme and say that the shorter the radar working wavelength, the better. If the wavelength is too long, there are difficulties; if it is too short, there are also disadvantages.

Radio waves with too short wavelengths will suffer great losses when propagating in the atmosphere. Therefore, they cannot travel far. Therefore, the wavelength of radar operation cannot be too long or too short, and it usually operates in the ultra-short wave or microwave band.

However, the radars on spacecraft are all equipped with long-wave radars. After all, in the vast universe, the ultra-long detection range of long-wave radars is still very practical. As for atmospheric attenuation, there is no need to worry about it. After all, how could there be an atmosphere in the universe!
Of course, this does not mean that shortwave radar is useless in space wars. In fact, longwave radar and shortwave radar each have their own advantages and disadvantages.

For example, although long-wave radar can easily detect objects thousands or even tens of thousands of kilometers away, its detection accuracy will naturally deteriorate as the distance increases.

As for shortwave radar, its detection energy is more concentrated, so its detection accuracy is naturally very high. Therefore, both types of radar are equipped on spacecraft.

The long-wave radar is responsible for detecting targets in advance, while the short-wave radar is used for close-range aiming and shooting, as well as intercepting meteorites.

Of course, this type of radar used for aiming and shooting has a special name, and this name is called fire control radar.

There is no other way. After all, shooting requires very high precision. If the accuracy of the radar is too poor, how can it guide the weapon to shoot?

Of course, shortwave radar is not only used as a fire control radar. Autonomous driving, which was particularly popular before Liu Xiu traveled through time, used millimeter-wave radar for detection to achieve autonomous driving.

(End of this chapter)