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Main Text Chapter Twenty-Three Martial Arts Absolute Learning

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    What is the key to playing a satellite?

    is tracking.

    The low-orbit satellites enter and leave the country quickly, and they circle the earth in one or two hours. "Whoosh¡ª" they passed overhead. The low-orbit reconnaissance satellite that Lao Zhao and the others sent to the future is only 300 kilometers high  , It circles the earth in an hour, such a high speed will make Pinellia face the same problem - this little thing runs too fast and is difficult to track, and if it is difficult to track, it is difficult to aim.  Difficulty receiving data.

    "Generally, how do you track satellite orbits when you launch satellites?" Bai Yang asked.

    "Use software, such as satorbit, heavens-above, ready-made free of charge and free of charge, you can find the orbital parameters of all public satellites, when it appears and when it is over the top, and which angle and direction are clear." Wang Ning moved  Sitting in the living room with a small bench, straightening the clothes hanger with a vise in his hand, "Stk is more professional, and similar software is everywhere, so that satellites all over the world will no longer have privacy from you."

    Obviously, in the bg4msr era, it is impossible to have these software anymore. Human beings are completely extinct, there is no Internet, no servers, and no one maintains and updates.

    "She definitely can't find the satellite orbit by herself. How can she find it? We just tell her here." Bai Zhen also moved a small bench and sat in the living room, holding a vise in his hand and cutting  Clothes hanger, "If you're lucky and the satellite re-orbits without deviation, then once we report the parameters here, she will be able to align soon."

    "Actually, the best solution is to take a relay satellite and put the relay satellite in a synchronous orbit at an altitude of 36,000 kilometers." Zhao Bowen also sat in the living room with a small bench in his hand.  Holding a vise, cut a clothes hanger and straightened it, "In this way, the relay star will always hang above the girl's head. The scout star will transmit the data to the relay star, and the relay star will transmit the data back to the ground.  You don¡¯t need to work hard to track it down, otherwise you¡¯ll have a spondylosis if you hold a Yagi antenna station on the roof and follow the satellite all day long.¡±

    "Then you should let them take a relay star."

    Bai Zhen cut off the hanger in his hand with a "click".

    "I mentioned it a long time ago, and I was scolded by the aerospace team." Zhao Bowen pouted, "They told me, are you still a human? You are not a human!"

    "The result? Didn't the relay star belt come with it?"

    Wang Ning also cut off the hanger in his hand with a "click".

    "Yes, but they warned me that this will greatly increase the difficulty of orbit design, and at the same time greatly increase the failure probability of satellite re-orbit." Zhao Bowen replied, "I said that there is no way, you can imagine a little girl  Is Tian standing on the roof of the building and holding the Yagi antenna in circles? Does she not have to do anything else?"

    The three old men sat around chattering, their hands were constantly busy, just like village women sitting together, chatting, gossiping and knitting sweaters, so many gossips came out like this, but Bai Zhen Wang Ning Zhao Bowen three  Instead of knitting needles and wool, the individuals held vise and hangers, and the sound of "clicking" came one after another.

    When Bai Yang came home from school in the afternoon, he saw them sitting together and abusing the clothes hanger, tearing the clothes hanger to pieces.

    What is this doing?

    This is making a Yagi antenna.

    The Yagi antenna is undoubtedly the most commonly used antenna type in the ham group. Compared with ordinary rod antennas and dipole antennas, the Yagi antenna has the advantages of high gain and high orientation. The signal is polarized in one direction. Generally speaking,  Other antennas are big bulbs that scatter light in all directions, and Yagi antennas are flashlights that only shine in one direction.

    Due to the polarization characteristics of the Yagi antenna signal, it is also the antenna that hams often use to play satellites. Because the power of ordinary amateur radio stations is very low, and the power of satellites is even lower, the connection between the radio station and the satellite is like a dumb talking to a deaf person. These two people  There are still thousands of miles between them-it is impossible for them to hear each other under normal circumstances, unless the mute masters martial arts skills to force the voice into a line.

    This forced sound into a line is the Yagi antenna.

    Bai Zhen put down the clothes rack in his hand, and picked up a slender wooden board from the floor. It was a leftover piece from some furniture factory. It was about one meter long.

    "What is the uplink and downlink frequency of that relay satellite?"

    "Uplink 144mhz, downlink 430mhz." Zhao Bowen replied.

    "The transmission speed of the u-band is a bit slow, you can use the x-band as well." Wang Ning said.

    "X-band reception is complicated. The connection between the scout satellite and the relay satellite is in the X-band. The relay satellite can store the data and send it back to Earth slowly. Don't worry about it." Zhao Bowen picked up the tape measure from the coffee table, "  How long is the reflector?"

    Valley </span>"Uplink two-meter wave, reflector length one meter, half wavelength."

    Bai Zhen took the measuring tape and measured the length of one meter on the straight clothes hanger: "No, this clothes hanger is not big enough, less than one meter. Is there a bigger clothes hanger?"

    Mom came out of the kitchen: "You have ruined all the drying racks at home."

    "I asked Xiaozhu to buy a large one."

    Wang Ning dialed the phone while speaking.

    That night Xiao Zhu ran all over the supermarkets in Qinhuai District.

    The clothes hanger is straightened and becomes a metal wire. Bai Zhen cut a one-meter-long metal wire and used it as the reflector of the Yagi antenna. The structure of the Yagi antenna is so simple that it can be made with wooden strips and a clothes hanger.  The reason why Bai Zhen and others chose Yagi is that it can use materials from anywhere, is easy to make, and is extremely friendly to novices.

    The wooden strips are used as the central axis, and five straight drying racks are placed vertically on the wooden strips in turn, which look like fish bones and form a Feng shape, which is a simple five-element Yagi antenna.

    The rearmost and longest clothes rack is called a reflector, and it concentrates the signal, like the mercury bowl in a flashlight.

    The penultimate clothes hanger is called the vibrator. The vibrator is the core of all antennas. It is the signal source. The current bounces wildly on the vibrator to generate electromagnetic waves.

    The remaining three clothes hangers are called directors. They guide the radiation direction of the radio wave and make it radiate in the direction that the antenna points to, so as to achieve the purpose of pointing and hitting.

    "Will you teach her to do it after you finish it?" Bai Yang sat aside and watched the three of them do their handicrafts. Twisting Yagi antennas with hands is the basic skill of the old ham.

    "When we confirm that this thing works, let her make an exact replica of the gourd painting over there." The old man replied, "Let's make do with it."

    "It's simple, and you can learn it once you learn it." Zhao Bowen said, "With the Yagi antenna, she can receive the signal from the satellite and then pass it on to us. The plan goes through the plan."

    "How long is the vibrator?"

    "96 centimeters, or 97 centimeters, you can cut it."

    "The remaining three are the same length."

    "Both are 88 centimeters."

    "Pay attention to the spacing, do we want a higher gain, or a better frequency band characteristic?"

    "Try it all. After it's done, take it to ao-91 to see how it works Also, pay attention to adjusting the impedance."

    "Close your eyes, 50 euros."

    "Which one of you brought the swr instrument?"

    "It's okay, I'll ask Xiao Zhu to bring one over!"

    The trio finally completed a uv double-section Yagi, and when they lifted it up and pointed it like a machine gun¡ªBan Xia also thought so, and when she finished the Yagi two days later, she felt that this  When the thing is swung, it looks like the Fangtian painted halberd used by Lu Bu in the horse.

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