When it comes to how to solve the problem of short radio transmission distance, we must first explain radio waves.

First of all, radio waves are generally divided into long-wave, medium-wave, and short-wave.

Of course, ultra-long wave, ultra-short wave, decimeter wave, centimeter wave, and millimeter wave were subdivided later, but this wave has no practical significance for Ma Qiang for the time being.

Because the long wave in the ground wave propagation, its propagation loss is small, the propagation is stable, the atmosphere is small, in the real history, for a long time, people think that the longer the wave, the better, but in fact, the long wave in the atmosphere of the ionosphere has a strong absorption effect on the long wave, so in the long-distance communication, the long wave is not as good as the short wave.

Short wave, that is, the frequency is between 3MHz ~ 30MHz and the wavelength is between 10m ~ 100m, although this wave is not conducive to the propagation of ground waves, but the ionosphere absorbs it very little, so after a reflection can get a jump distance of 100 to 4,000 kilometers. After several successive reflections from the ionosphere and the earth, the propagation distance can reach great distances.

To what extent, let's put it this way, after the liberation, many spies lurking in the mainland used short-wave radios, which could be said to be 5 watts around the world in those years, and even more remarkable in the era of the late Han Dynasty.

And the reason why later radio stations can be so good is not only because of the discovery of the advantages of short wave, but also because of the most important invention of the twentieth century - the electron tube!

The electron tube, and even the transistor that was further invented later, greatly changed the world in the twentieth century and laid the foundation for the emergence of the later information age.

And Ma Qiang has always asked Yan Fa to develop an electron tube, and he is ready to develop a new generation of radio stations after pointing out the technological point of the tube!

What is the function of the tube, let's put it this way, why the transmitter has a short transmission distance, you can understand why you can't hear it from the opposite building, the sound is too small!

So how do you make him hear?

Be louder! No, add a horn!

The tube is this horn!

So what is an electron tube, it is easy to understand it by another name - vacuum tube.

As we all know, the vacuum environment is more conducive to the flow of free electrons, so the main use of the electron tube is to make a small electrical signal into a large one, and add a big horn to the transmitter and receiver, so that you can shout farther and hear more clearly.

Of course, the electron tube is a small thing compared to the transistors that appear later, but the manufacturing requirements of the transistor are higher, and the core technology of the electron tube is to put something in a vacuum glass tube.

Does this sound familiar?

That's right, this thing is actually an adjunct to the light bulb technology, and the inventor is Edison, so the original electron tube was invented in 1883, that is, the era of the outbreak of the Sino-French War.

Looking at a wooden plate that Yan Fa was holding carefully, on the wooden plate was a thumb-sized cylindrical glass container, and two metal rods were sticking out of the container, Ma Qiang felt cute no matter how he looked at it.

Compared with those diodes in later generations, this thing is naturally not much thicker, but in Ma Qiang's eyes, this is definitely a cute little Lori.

"Tell me, how did you do that?"

"At first, we couldn't think of how to put the metal in and then turn the glass container into a vacuum, but then we suddenly remembered that the melting point of the metal is higher, so we can first turn the glass container into a vacuum, and then burn the metal into the vacuum, and then insert the metal red, and this is a success!"

"Not bad, good thinking, reverse thinking, very good, I will work with you during this time, and strive to make the triode, and then our communication soldiers will be much easier!"

In this era without any clutter, Ma Qiang's radio half-hang is enough to open the door to electronic communication.

Ma Qiang felt that he was back in that world, constantly experimenting and exploring with Yan Fa and others every day, and the military and political affairs were left behind, anyway, Jia Xu and others helped him deal with it.

It was also at this time that Ma Qiang felt that he was actually still a scientist, not an iron-blooded politician.

Ma Qiang was doing radio experiments, but the princes of the world couldn't stop and wait for him, and countless people were staring at Guangzong's every move.

Ma Qiang's opening of the imperial examination and the organization of caravans to go out to buy food made the surrounding princes judge that Ma Qiang was preparing to recuperate for a period of time, and they couldn't help but relax their precautions against the Zhenbei army.

Yuan Shao even started to go south directly with the army.

Now it can't be said that it is Dong Zhuojun, let's call it Niu Dong Lianjun, because the rest of Dong Zhuo's current department has gradually divided into Niu Fu and Dong Min.

Niu Fu is Dong Zhuo's other son-in-law, Dong Min is Dong Zhuo's younger brother, it stands to reason that Dong Min should inherit Dong Zhuo's political legacy, after all, they are all surnamed Dong, but who called Dong Min has never served in Dong Zhuo's army, even after Dong Zhuo entered Luo, Dong Min almost always served as a guard in Yiwu, and Li Dao, Guo Yan, and Zhang Ji were all Niu Fu's subordinates, so they were naturally closer to Niu Fu, Dong Yue and Duan Xuan supported Dong Min, and the two factions faintly fought with each other, just because Niu Fu and Dong Min's personalities were not so strong, but nothing major happened.

Yuan Shao went south to Hedong, and did not continue to go south, but continued to meet with the generals of the Baibo Army, and then it was a beautiful combination of punches, coercion and temptation, and within a few days, the Baibo Army in Hedong either handed over the military power and left with the property, or gave up the city and became Yuan Shaoxin's direct subordinates.

As for Cao Cao, after returning to Yanzhou, he hyped Yanzhou's victory in recovering Taishan County, but everyone could see that Bao Xin's death had a great impact on Cao Cao.

The relationship between Bao Xin and Cao Cao is difficult for outsiders to understand, it is a real friend of life and death, Cao Cao handed over all Bao Xin's soldiers and horses to the commander of Yu Ban, and took Bao Xin's two sons Bao Shao and Bao Xun to his own mansion, and ate and lived with Cao Pi and others, which can be regarded as a lifetime of wealth.

At the same time, Cao Cao learned a news from the report of Xun Yu and others that made him angry.

In this war, the orders of the counties to collect and transport Xun You's grain and grass were all blocked, and even Yang Feng Yin disobeyed, which also led to Cao Cao's poor grain route after pursuing Mount Tai.

Cao Cao couldn't help but record Bao Xin's death on the Yanzhou scholars.

But now is not the time for revenge, and now Cao Cao wants to recruit troops and buy horses again, and prepare to attack Xuzhou again.

At this time, the news that Jizhou would hold the imperial examination again reached Yanzhou.

Cao Cao saw that Ma Qiang's thirst for talents was so strong, and he was not to be outdone, and began to hold the work of promoting filial piety and Maocai in Yanzhou, and recruited notices everywhere to express his thirst for talents.