Chapter 885 Optical phased array radar


    For back-to-back double-sided array "camera scan", the difference between the 120° field of view and the 150° field of view may not be particularly big.


    After all, all it takes is moving the plate a little.


    But for small and medium-sized early warning aircraft using fixed double-sided arrays, that is, balance beams or T-shaped antennas, the meaning is completely different.


    Equivalent to reducing the detection blind zone to half of its original size.


    More importantly, it can reduce the possibility of the AWACS being forced to adjust its route in order to change the detection area.


    As a technician, Wang Xiaomo was naturally very happy to find that someone was interested in the field he was researching, so he immediately gave a more detailed explanation:


    “You know, the so-called phased array radar is actually an electronically controlled scanning using a phase shifter to control the beam, replacing the mechanical scanning that used a mechanical structure to control the rotation of the antenna array, so it can achieve an extremely high target refresh rate.”


    “However, at this point, we still only solved the problem of target refresh rate. If the phased array radar wants to obtain better detection capabilities, it also needs to have a large enough instantaneous bandwidth and scanning angle.”


    "But these two attributes are contradictory on the same radar. The greater the pointing deviation of the radar, the smaller the available instantaneous bandwidth. Generally speaking, the impact of the instantaneous bandwidth is ±45°, which is within the 90° pointing range. Not big, so shipborne phased array radars that are not sensitive to weight and volume, such as the American Aegis and the Sea Star system we are developing, all use 4-sided arrays to ensure the best detection results. "


    “If no wide-angle scanning technology is used, then when the array normal lobe width is 2° and the field of view reaches ±60°, which is a 120° pointing range, the allowed relative signal instantaneous bandwidth is only 1%, and the antenna physics The larger the size, the greater the demand for relative signal instantaneous bandwidth, which is completely unacceptable for high-resolution detection.”


    “Therefore, the vast majority of phased array radars put into use use real-time delay lines in each transceiver channel to compensate for the spatial distance difference between antenna units.”


    "The ideal situation is to use a delay line on each unit of the phased array antenna, but this means tens of kilometers of extra cables for a phased array radar with thousands of transmitting units. On the one hand, The cost and size are unacceptable. On the other hand, such high-density cables will also produce very strong interference. "


    “So the current common practice is to divide the phased array antenna into a series of sub-arrays, continue to use phase shifters for the units inside the sub-arrays, and use real-time delay lines between sub-arrays.”


    “However, for large phased array antennas, dividing the sub-arrays will result in many sub-array-level grating lobes in the field of view, causing the antenna side lobes to increase. In short, the final result is the current 120° scanning angle. Single-sided antenna, all aspects of performance are acceptable…”


    …”


    After all, he is a senior academician who has been immersed in the field of radar for most of his life, and his explanations are simple and profound.


    Even Zhang Hongbiao who was following him felt that he understood everything.


    As for Chang Haonan…


    In fact, when Wang Xiaomo had just spoken a few sentences, he had already remembered that Huo Penghua had mentioned the same term during a seminar some time ago.


    ??A certain length of wire is also used to compensate for the phase difference between different signals.


    It’s just that in the end…


    Well, it’s not the end yet.


    ?However, at least for now it has been replaced by optical fiber.


    ?Of course, in that laser processing equipment, the main purpose of replacing optical fibers is simply to reduce signal delay.


    ?Compensating the signal phase difference is just a matter of course.


    We’re all here, let’s just put them on together.


    But similar ideas seem to be introduced to radar—


    This time, it’s not just about replacing cables with fiber optics.


    Instead, a programmable optical delay unit is used combined with a microwave photon phase shifter to form an optical beam forming network, which fully realizes phase control of the antenna array elements by photoelectric signals...


    Chang Haonan''s thinking continued for a long time, until a sudden cold wind interrupted his thoughts.


    ?However, this is enough.


    "Comrade Haonan, what new idea did you just...think of?"


    ?Wang Xiaomo asked with concern.


    ??He did not speculate on the specific technical aspects of radar. After all, although Chang Haonan had demonstrated his knowledge background in signal processing, he had almost never been involved in the research and development of radar itself before.


    So I just thought that Chang Haonan had some new ideas about the follow-up development route of the early warning aircraft.


    “There is some inspiration, but it’s not perfect yet…”


    Chang Haonan nodded:


    "After I go back this time, I will do some calculations on a theoretical level. If the results are more optimistic, I will discuss it with you, Academician Wang."


    He can still distinguish the priorities of things.


    ?Wang Xiaomo is an academician of the Academy of Engineering and has spent his career solving problems at the engineering application level.


    ?Looking at the delivery ceremony tomorrow, telling Wang Xiaomo something that cannot even be called an idea, but can only be regarded as an idea at best, will not bring any real help other than making the other party feel like a cat scratching his heart.


    It is better to improve the idea and at least come up with a complete theoretical calculation result before discussing this matter.


    ?However, Wang Xiaomo guessed some clues from the words in Chang Haonan''s answer.


    Since the latter mentioned "theoretical calculations", it is obvious that the inspiration just mentioned is by no means a large-scale matter such as the development route of early warning aircraft.


    It is related to specific technologies.


    As for what specific technology it is...


    Of course Wang Xiaomo doesn’t know yet.


    ?However, since Chang Haonan didn''t say it directly, he wasn''t going to forcefully get to the bottom of it.


    Sometimes, it might be better to retain some curiosity...


    The two people, who each predicted the other''s prediction, looked at each other tacitly, then ended the topic for the time being and walked forward side by side.


    Only the confused Zhang Hongbiao and Liang Shaoxiu were left, messy in the cold wind...


    …


    the next day.


    March 25, 9 a.m.


    The delivery ceremony started on time. As for the process, it is naturally the same as the third one.


    First, several leaders, including Zhang Hongbiao, spoke.


    Then representatives of R&D personnel and pilots expressed their opinions.


    Then the plane with the big red flowers was dragged from a little distance to the ceremony site for a group photo.


    Done.


    The person who led the team to pick him up at the airport was even an old acquaintance of Chang Haonan.


    Shen Tao.


    ?However, this is not too surprising.


    The 4th Regiment of the 2nd Division of Hainan Airlines is still the only full-time special aircraft unit in Hainan Airlines and even the entire military. It is also the unit with the most experience in serving Y-8 III platforms.


    Since the range of the air-tight Y-8 is truly astonishing, the genuine transport aircraft force has little need for these later improved models, and most of its production capacity has become special aircraft platforms.


    “Deputy Commander Shen.”


    Chang Haonan had already noticed the other party when he was on the stage. After the ceremony, he immediately walked up and said hello:


    "haven''t seen you for a long time."


    The last time the two met was at the 50th National Day military parade.


    A year and a half later, Shen Tao has a star on his shoulder.


    The position was also promoted from the commander of the 4th HNA Regiment to the deputy division commander of the 2nd Division.


    Just because the age limit for large aircraft pilots is relatively loose, they still serve as captains within the 4th regiment establishment.


    Shen Tao''s eyes were originally staring at the Air Police 200 attentively. After hearing Chang Haonan''s voice, he realized that there was someone behind him, so he turned around suddenly.


    “Mr. Chang?”


    I don’t know if it was Chang Haonan’s illusion, but there didn’t seem to be much excitement in Shen Tao’s tone about installing the new model:


    “Hello, hello…”


    “I feel like Deputy Commander Shen is not very interested…”


    Chang Haonan said half-jokingly, thinking that the other party was tired after spinning for too long.


    ?This situation also occurs after he works for a long time.


    Not interested in anything.


    ?However, Shen Tao''s reaction was to slightly twitch the corners of his mouth, trying to put on an excited expression.


    The result failed.


    So he had to sigh:


    “It’s just some trivial matters at the HNA organization level, no need to mention more...”


    After hearing what the other party said, Chang Haonan suddenly remembered something -


    In 2003 in the previous life, the unified Naval Aviation Command was abolished.


    From then on until 2016, all naval aviation divisions were under the simultaneous jurisdiction of the Aviation Department under the Naval Command, the Aviation Technical Support Department under the Naval Equipment Department, and the three major fleets.


    From the perspective of hindsight, this had a rather negative impact on the organizational construction and equipment training level of the naval aviation force.


    As for such a big move, it is normal for news to leak out one or two years in advance.


    Shen Tao is probably worried about this matter.


    ?However, this kind of issue involving the construction of the military system is quite sensitive, and Chang Haonan knew that it was impossible to intervene directly.


    So, I had to prepare to talk about other things with the other party.


    ?But before he could speak, Shen Tao took the initiative to change the topic:


    “Anyway, I would like to thank your aviation technology department for providing more advanced equipment.”


    “If we could have had the things we have now at this time five years ago, I’m afraid... it would not be impossible to rewrite history.”


    ? Shen Tao, then deputy commander of the 4th Regiment, naturally participated in the naval and air exercise in 1996.


    ??It’s just that the main equipment of the 4th Regiment at that time was only a few Y-8Xs used for maritime surveying and patrolling. They could only wander around the periphery for a few times, looking helplessly at the tense core exercise area.


    Shen Tao still remembers that feeling of black eyes and burning heart.


    Now the first early warning aircraft has finally been installed. Although it is only a transitional model from "backup to regular" that year, it at least gives the special aircraft unit the ability to directly participate in sea and air confrontations.


    “Let bygones be bygones.”


    ?Chang Haonan patted the other party on the shoulder:


    “If I have to say it, it was the stimulation of that incident that made me determined to work hard...”


    ?This sentence is not wrong, but it is not completely correct.


    It is true that he was determined to become stronger back then, but after all, human abilities have their limits.


    What really changed everything was the wave of rebirth with memories and experiences, and of course the system.


    It’s just that this is something Chang Haonan cannot tell anyone...


    “Is there such a thing?”


    Shen Tao naturally didn''t know the twists and turns. He just glanced at Chang Haonan next to him with a slightly surprised look, and finally there was a smile in his tone:


    “Then based on this calculation, the Americans actually suffered a big loss..."


    (End of this chapter)