Chapter 885 Optical Phased Array Radar

For the back-to-back double-sided array "machine phase scanning", the difference between the 120° field of view and the 150° field of view may not be particularly large.

After all, it only takes a little movement of the plate.

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

This is equivalent to reducing the detection blind area to half of its original size.

More importantly, it can reduce the possibility that early warning aircraft will be forced to adjust their routes in order to change their detection areas.

As a technician, Wang Xiaomo was naturally very happy to find that someone was very 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 that uses phase shifters to control the beam, replacing the mechanical scanning that used to use mechanical structures to control the rotation of the antenna array. That's why it can achieve an extremely high target refresh rate."

"However, at this point, we have 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 sufficiently large instantaneous bandwidth and scanning angle."

"But these two properties are contradictory on the same radar. The greater the pointing deviation of the radar, the smaller the available instantaneous bandwidth. Generally speaking, within the pointing range of ±45°, that is, 90°, the instantaneous bandwidth has little impact. Therefore, for shipborne phased array radars that are not sensitive to weight and volume, such as the US Aegis and the Sea Star system we are developing, four-sided arrays are used to ensure the most ideal 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°, that is, a 120° pointing range, the allowed relative signal instantaneous bandwidth is only 1%. Moreover, the larger the physical size of the antenna, the greater the demand for relative signal instantaneous bandwidth, which is completely unacceptable for high-resolution detection.”

"Therefore, most of the phased array radars put into use will use real-time delay lines in each transmit and receive channel to compensate for the spatial path difference between antenna units."

"The most ideal situation is to use a delay line on each unit of the phased array antenna, but this means tens of kilometers of cables are added out of thin air for a phased array radar with thousands of transmitting units. On the one hand, the cost and volume are unacceptable. On the other hand, such high-density cables will also cause 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 in the units within the sub-arrays, and use real-time delay lines between the sub-arrays."

"However, for large phased array antennas, dividing the array into subarrays will result in many subarray-level grating lobes in the field of view, causing the antenna sidelobes to rise. In short, the final result is the current single-sided antenna with a scanning angle of 120°, which has 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 explanation is easy to understand.

Even Zhang Hongbiao, who was standing next to him, felt that he understood most of what was said.

As for Chang Haonan...

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

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

But 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 changing the optical fiber is simply to reduce signal delay.

Compensating for the signal phase difference is only a side effect.

Since we are here, we might as well change them together.

But similar ideas seem to be able to be introduced into radar——

This time, it’s not just about replacing cables with optical fibers.

Instead, a programmable optical delay unit is combined with a microwave photon phase shifter to form an optical beamforming network, which completely realizes the phase control of the antenna array elements by the optoelectronic signal...

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

However, this is enough.

"Comrade Haonan, did you just... come up with any new ideas?"

Wang Xiaomo asked with concern.

He did not guess about the specific technical level of the radar. After all, although Chang Haonan had demonstrated knowledge background in signal processing, he had hardly been involved in the research and development of the radar itself.

Therefore, I just thought that Chang Haonan had some new ideas about the subsequent development route of the early warning aircraft.

"I have some inspiration, but it's not perfect yet..."

Chang Haonan nodded:

"After I return this time, I will do some theoretical calculations. If the results are optimistic, I will discuss this with you, Academician Wang."

He can still distinguish the priorities of things.

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

Seeing that the delivery ceremony is tomorrow, telling Wang Xiaomo something that cannot even be called a thought and can only be regarded as an idea at best will not bring any substantial help except making him feel uneasy.

It would be better to perfect the idea, at least come up with a complete theoretical calculation result, before discussing this matter.

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

Since the latter mentioned "theoretical calculations", it is obvious that the inspiration just mentioned is by no means something as general as the development route of early warning aircraft.

It’s related to specific technology.

As for what specific technology...

Of course Wang Xiaomo didn’t know yet.

However, since Chang Haonan didn't say it directly, he didn't intend to force the matter.

Sometimes, it's better to keep some curiosity...

The two of them, each predicting the other's prediction, looked at each other tacitly, then temporarily ended the topic and walked forward side by side.

Only Zhang Hongbiao and Liang Shaoxiu were left, both confused and bewildered, standing in the cold wind...

……

the next day.

March 3, 25: a.m.

The delivery ceremony started on time.

As for the process, it is naturally the same old three.

First, several leaders including Zhang Hongbiao spoke.

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

Then they towed the plane with the big red flower hanging on it from a little further away to the ceremony site for a group photo.

Get it 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 very surprising.

The 2th Regiment of the 4nd Division of the Naval Aviation is still the only dedicated special aircraft unit in the entire Naval Aviation and even the entire army, and is also the unit with the most experience in serving the three types of Y-8 platforms.

Since the range of the airtight Y-8 is so amazing, the genuine transport aircraft units do not want these later improved models, and most of the production capacity has become special aircraft platforms.

"Deputy Commander Shen."

Chang Haonan had already noticed him when he was on the stage just now. After the ceremony, he immediately walked up to him and said hello:

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

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

After a year and a half, Shen Tao already has a star on his shoulder.

His position was also promoted from the commander of the 4th Naval Aviation Regiment to the deputy commander of the 2nd Division.

It’s just that the age limit for large aircraft pilots is relatively loose, so he still serves as the captain of the 4th Regiment.

Shen Tao's eyes were originally focused on the KJ-200. After hearing Chang Haonan's voice, he realized there was someone behind him, so he turned around abruptly.

"Mr. Chang?"

I don't know if it was Chang Haonan's illusion, but Shen Tao's tone didn't seem to contain much excitement about receiving the new model:

"Hello Hello……"

"It seems that Deputy Commander Shen is not in a very good mood..."

Chang Haonan said this half-jokingly, thinking that the other party was just a little tired after working non-stop for too long.

This also happens after he works for a long time.

I have no interest in anything.

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

It failed.

So I could only sigh:

"It's just some trivial matters at the HNA organization level, no need to mention it..."

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

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

From then until 2016, the naval aviation divisions were under the 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 very negative impact on the organizational construction and equipment training level of the naval aviation.

It is normal for rumors of such major moves to leak out a year or two in advance.

Shen Tao is probably worried about this matter.

However, this issue involving the construction of the military system is quite sensitive, and Chang Haonan knows that he cannot intervene directly.

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

But before he could open his mouth, Shen Tao took the initiative to change the subject:

"Anyway, I still want to thank your aviation technology department for providing more advanced equipment."

"If we had what we have now at this time five years ago, I'm afraid... it wouldn't be impossible to rewrite history."

Shen Tao, then deputy commander of the 96th Regiment, naturally also participated in the 4 sea and air exercise.

However, the main equipment of the 4th Regiment at that time was only a few Y-8X aircraft used for maritime surveying and patrolling. They could only wander around the periphery and watch the tense situation in the core exercise area helplessly.

Shen Tao still remembers vividly the feeling of being in the dark and anxious.

Now the first early warning aircraft has finally been put into service. Although it was only a transitional model for "backup to regular use" at that time, it at least enables special aircraft units to have 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 was the stimulation of that incident that made me determined to work hard..."

This statement is not wrong, it is just not completely correct.

It is true that he worked very hard back then, but human ability has its limits after all.

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

However, this is something that Chang Haonan cannot possibly tell anyone...

"Is there such a thing?"

Shen Tao naturally didn't know the twists and turns, he just glanced at Chang Haonan beside him with a little surprise, and finally there was some smile in his tone:

"So if you calculate it this way, the Americans are actually at a big loss..."