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, just move 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.
It is 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 studying, 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 a very 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, ±45°, that is, within the 90° pointing range, the instantaneous bandwidth is Bandwidth has little impact, 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-area arrays to ensure the best Detection effect.”
“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.”
“So, the vast majority of phased array radars put into use, Real-time delay lines will be used in each transceiver channel to compensate for the spatial path difference between antenna units. "
"The ideal situation is to use a delay line on each unit of the phased array antenna, but For phased array radars with thousands of transmitting units, this means that dozens of kilometers of cables are added out of thin air. On the one hand, the cost and volume are unacceptable. On the other hand, such high-density cables will also produce unusual Strong interference. ”
“So the current common practice is to divide the phased array antenna into a series of sub-arrays, and continue to use phase shifters for the units inside the sub-arrays, and between the sub-arrays. Use real-time delay lines. ”
“However, for large phased array antennas, dividing the sub-arrays will cause many sub-array-level grating lobes in the field of view, causing the antenna side lobes to increase. In short, it is the final choice. The result is the current single-sided antenna with a 120° scanning angle, with acceptable performance in all aspects..."
"..."
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 it during the seminar some time ago. a same noun.
A certain length of wire is also used to compensate for the phase difference between different signals.
It’s just 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 the optical fiber is to simply reduce the signal delay.
Compensating the signal phase difference is just a matter of course.
We’ve already arrived, let’s just put them on together.
But similar ideas seem to be introduced to radar -
This time, it is not just about replacing cables with optical fibers.
Instead, a programmable optical delay unit combined with a microwave photon phase shifter is used to form an optical beam forming network, fully realizing the 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 is not perfect yet..."
Chang Haonan nodded:
"After I go back this time, on a theoretical level, Calculate it, and if the result is optimistic, we can 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 basically spent his career solving problems at the engineering application level.
Seeing that tomorrow will be the delivery ceremony, 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 substance except making the other party feel like a cat scratching his heart. help on.
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.
Rather, it is related to specific technologies.
As for the specific technology...
Wang Xiaomo certainly doesn’t know yet.
However, since Chang Haonan did not tell him directly, he was not prepared to forcefully get to the bottom of it.
Sometimes, it may 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 am.
The delivery ceremony started on time. As for the process, it is naturally still the same as the third one.
First, several leaders, including Zhang Hongbiao, spoke.
Then representatives of R&D personnel and pilots expressed their stance.
Then the plane with the big red flower hanging on it was dragged from a little distance to the ceremony site for a group photo.
Done.
The person who led the team to pick up the plane was even an old acquaintance of Chang Haonan.
Shen Tao.
However, this is not very 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 army. 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:
"Long time no see."
The last time the two met was at the 50th Anniversary 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 commander of the 2nd Division.
But because the age limit for large aircraft pilots is relatively loose, they still serve as captains within the 4th regiment.
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 Shen Tao’s tone didn’t seem to have much excitement about installing the new model:
“Hello, hello...”
“It feels like Deputy Shen The teacher's interest is not very high..."
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 I had to sigh:
“It’s just some trivial matters at the organizational level of HNA, no need to mention it...”
After hearing what the other party said, Chang Haonan suddenly remembered something -
In 2003, in the previous life, the unified naval aviation command had been abolished.
From then 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 quite 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 the news to leak out a year or two 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 to the other party about other things.
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."
During the sea and air exercise in 1996, the deputy commander of the 4th Regiment at the time Shen Tao, the group leader, naturally also participated.
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.
The feeling of dark eyes and burning heart is still fresh in Shen Tao's memory.
Now the first early warning aircraft has finally been installed. Although it is only a transitional model from the "backup to regular" that year, it at least gives the special aircraft unit the ability to directly participate in sea and air confrontations.
"Let the past go by."
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. Work hard to become stronger..."
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 changes everything is the wave of memories and experiences, and of course the rebirth of the system.
However, this is something that Chang Haonan cannot tell anyone...
"Is there such a thing?"
Of course Shen Tao doesn't know what's going on. After twisting and turning, he glanced at Chang Haonan next to him with a slightly surprised look, and finally there was a smile in his tone:
"So calculated, the Americans have actually suffered a big loss..."
(End of this chapter)