Radar was invented thanks to bats.

When the bat flies at night, the mouth will emit ultrasonic waves, this sound, the human ear can not hear, but the bat ears can hear, the ultrasonic wave is like a wave forward, when it encounters an obstacle, it is reflected back, transmitted to the bat's ear, the bat immediately changes the direction of flight.

So even if the bat is blindfolded, it can still catch moths and mosquitoes in the dark, and no matter how it flies, it won't collide with anything.

The principle of radar is similar, the radar transmitter generates enough electromagnetic energy, and then the antenna radiates this electromagnetic energy into the atmosphere, concentrates it in a very narrow direction to form a beam, and propagates forward.

When an electromagnetic wave encounters a target in the beam, it will be reflected in all directions, and a part of the electromagnetic energy will be reflected back to the direction of the radar and will be captured by the radar antenna. The energy obtained by the antenna is sent to the receiver through the transceiver transfer switch to form the echo signal of the radar.

This is a great application of human bionics, and it is bound to make waves in the world of fairy swords.

Thanks to Cui Xiaoxiao's recent efforts to ask Wei Gong to make his own power generation device, he was able to make this sword in a short period of time.

The emission principle of electromagnetic waves is mainly the use of electromagnetic oscillation, through the two ends of the capacitor through a strong enough frequency current, to generate electromagnetic energy, and then emit into the air.

Electromagnetic waves are different in frequency, wavelength, and can travel different distances.

To be precise, the lower the frequency, the longer the wavelength, and the farther the long wave travels, because when the wavelength is too short, it will be attenuated due to water vapor and oxygen in the atmosphere, and when the electromagnetic wave frequency is less than 1GHz, the atmospheric attenuation is negligible.

According to the frequency formula of electromagnetic waves: f=1 /[2π*root number (LC)], the inductance L and capacitance C in the oscillation circuit are physical quantities that directly affect the frequency value, and the frequency of electromagnetic waves can be changed by changing L or C or LC at the same time.

From the point of view of convenient and reliable operation, most of them change the frequency by changing the capacitor C.

Emiya's radar sword controls electromagnetic wave frequencies of about 3MHz, which is to the extent that atmospheric attenuation can be ignored.

It's just that the [energy] side will be a little pitfall.

Because he didn't find a suitable power source, he can only provide electricity through the [Wood] Lightning Direction skill.

Now this radar sword, there are only three positions for the emission of electromagnetic waves, they will fly quickly in the air in a fixed direction, the speed of electromagnetic waves is almost the same as the speed of light, and when it encounters obstacles, it will be partially reflected back.

If you make a 360-degree transmission wave in all directions, the energy requirements for the sword holder are very high, when the transmitting surface is narrower, the better the wave's ability to constrict, and with the same energy, it can travel farther.

Even if it is the current three electromagnetic wave emission methods, it still consumes a lot of [essence].

Fortunately, today is only used to test performance, and if it is to be put into full-fledged military use, the sword of Emiya will probably have to be operated by ten people in turn every day.

……

In fact, compared with the emission and reception of electromagnetic waves, the production of Emiya's [display] is the most technically difficult and time-consuming thing.

In order to accurately convert the received electromagnetic wave signal into an optical signal and display it on the screen, Emiya has tried more than a dozen fluorescent materials before finally making such an unsatisfactory thing.

The photosensitive material needs to have two important functions, one is that when the electromagnetic wave is received, it will excite the electrons arranged on the sword grid, and then hit the phosphor screen, and then excite the photosensitive material above for display.

The second is reuse, after the light is revealed, it must be restored, and then wait for the next target delivery.

……

In addition to the incompleteness of the [power supply] and [display], this sword also has a disadvantage, that is, it can only carry out directional monitoring and judgment of the opponent's upward target, but it cannot make accurate calculations of distance.

Although Emiya also knows the principle of calculation, the distance calculation is based on the Doppler effect, the angle and velocity difference between the transmitted and reflected waves, and the time, the wavelength becomes longer when the target is farther away, and the wavelength becomes shorter when the target is approaching the radar.

However, the real technical difficulty lies in the production, one is that there needs to be a converter that can convert electromagnetic waves into electrical signals, and the other is that there needs to be a miniature microcontroller that can complete signal storage, and simple calculations and convert them into signal output.

Before the production of single-chip microcomputer, Weigong had to learn the knowledge of microelectronics and integrated circuits from Cui Xiaoxiao, and to complete the production of electronic screens in the real sense, he also needed to learn the principles of transistors and cathodes from Cui Xiaoxiao......

In short, layer by layer, Wei Gong is not able to complete the production of a Doppler radar independently, there is a lot of knowledge that needs to be supplemented, and it is already a miracle that he can provide this imperfect radar sword in a short time.

Time is limited, and he can only do it here.

But for the defense of the entire Yunmenggang, it should be basically enough.

Emiya plans to pass this time, and when his battery device and generator are out, he can really open the door to [electromagnetic], and he can make real military radar.

At that point, it will be possible to achieve fully automated monitoring without manual operation.

……

Emiya held his sword high above his head, as if he was about to make some earth-shattering move.

But after waiting for a long time, nothing happened in the eyes of everyone.

Except that the sword in his hand kept spinning.

The monitor on the sword grid in his hand lit up with a red dot, then flickered, and the next time it appeared, it was a little closer.

"Patrol Ship No. 1, in the direction of 30 degrees east-north of where you are now, there is a target, you can intercept it, and before my instructions change, follow this direction."

Wei Gong picked up the Qiankun Mirror, and then commanded calmly.

At this moment, he suddenly remembered something, if there is no electromagnetic wave long-range communication in the world of fairy swords, what is the principle of the Qiankun mirror in his hand to do this?

And the sending and receiving signals of this thing are much more stable and clear than he imagined.

Thinking of this, he couldn't help but sigh, the traverser named Yue Chuanwo back then was really a god man!

……