On the one hand, there are traditional radar factories, such as the 607 Institute, which is a subordinate research institute of the Third Aircraft Department, which specializes in radar, and the 204 and 208 radars on the Jian-8 are what they are engaged in.

However, because of technical problems, they have not been able to break through, and they have not been able to attack the more advanced pulse Doppler radar, a simple single pulse radar, has already stumped them.

When the Ministry of Aviation Industry could not break through, they were also asking the Ministry of Electronics Industry for help, and the 14 institutes were originally engaged in large-scale radars on the ground, and they were mobilized to engage in this kind of airborne radar, after all, if you want to develop advanced fighters, you must have advanced airborne radars.

What Qin Feng didn't expect was that his own actions were also very fast, and now, his sister even participated in Mr. Zhang's project to study the very difficult flat slot radar antenna?

Although he is not a professional, Qin Feng knows the difficulty.

At present, the 204 radar is still the most common parabolic antenna radar, relying on the principle of reflection, gathering all the radar waves to one point and transmitting them, this kind of efficiency is quite low, and even one percent of the energy is not converted into electromagnetic waves, all of them are emitted.

The overall profile of the parabolic radar antenna is high and the volume is large. Especially when the antenna is rotated as a whole, it will greatly occupy the space of the nose, so that it is very difficult to scan, and the head of such a large machine can only be equipped with a small radar antenna, otherwise it can not be rotated, in order to solve these difficulties, the Cassegrain antenna appeared.

The Cassegrain antenna is designed to solve these problems, it adds a secondary reflective surface in front of the parabolic antenna, so that the electromagnetic waves emitted by the magnetron are first optimized to make it present a more ideal distribution, and are reflected back to the main reflective surface, which then turns the shaped spherical wave into a plane wave and radiates it into free space.

In this way, the energy of the magnetron is utilized, the antenna aperture efficiency is improved, the gain is increased, the focal diameter ratio is greatly reduced, the overall profile of the antenna is reduced, and the volume is reduced.

However, the addition of this secondary reflector will block part of the electromagnetic waves, so the engineers used their brains to turn the entire antenna by 180 degrees, changing the position of the secondary reflective surface to a polarized grid parabola, and the position of the main surface to a polarized torsion plate.

This is the inverted Cassegrain antenna, which has been used until now.

Even the Su-27 fighters, which had just been equipped with the Soviet Union, used this antenna, which has almost reached the peak of parabolic antennas.

Compared with parabolic antennas, there is a more suitable antenna, which is the flat panel array antenna.

As the name suggests, its surface is a flat plate, on which there are dozens to hundreds, or even thousands of small unit antennas evenly arranged on the array surface according to certain rules, spacing, etc. In this way, the performance of a single antenna unit may not be good, but relying on the many unit antennas on the antenna array, working together, can achieve a high gain, narrow beam, and even ultra-low sidelobe.

In the 70s, the United States' airborne radar began to make a comprehensive transition to flat-panel array antennas, leading Europe by more than a decade.

There are several kinds of flat panel array antennas, the most commonly used of which is the waveguide slot array, in which the waveguide surface of the flat panel antenna is slitted to make a small gap become an antenna and radiate electromagnetic waves. The performance of this antenna is quite good and allows for a decent energy radiation.

Speaking of radar, there are always people who like to say that the radar of the MiG-25 can burn rabbits, but what is the use of burning rabbits? That's a microwave oven, not a radar, the MiG-25 radar with super perverted power, has not gotten a detection distance of 100 kilometers, but look at the Tomcat fighter, the power is only a fraction of the MiG-25 radar, and the detection range of 300 kilometers has been achieved, of which the flat slit antenna is a very important part.

However, this requires technology very much, and even Europe has not yet mastered its processing technology, and as for the Soviet Union, it has never been done in history, so it simply bypassed it and went directly to the phased array radar.

The processing of this gap is the most difficult, because the width of this gap is on the order of wavelength!

The error is quite small, there can not be any burrs, and it is not one, it is often hundreds, thousands, the width should be exactly the same, the position should be very small, a slight mistake, it will be a waste!

It can be said that this is a Mount Everest of the developers of airborne radar.

Now, when Qin Feng heard that he was overcoming this difficulty, he immediately showed an excited expression: "Xiaoxue, can you take us to have a look?" ”

"This, you and Teacher Zhang both know each other, of course you can go." Qin Xue said: "However, Teacher Zhang, she is very busy, she may not be able to say a few words, I always ask my senior brother to give advice, and I haven't seen Teacher Zhang much." ”

Because of the delay of ten years, there is a big gap between our own side and the world level, in order to catch up, everyone is working day and night! Qin Feng looked at Gu Tingting in front of her, she had also been busy for a long time, although she looked relaxed now, but after she went back, she might be busy again.

After eating, several people walked into the university campus.

It's summer vacation now, there are not many people on the university campus, but the people who can see it are coming and going in a hurry, here is the ocean of knowledge, the college students here are the pride of the sky, they are constantly diligent and enterprising in the ocean of knowledge.

Teacher Zhang led a group in an inconspicuous small building, and Teacher Zhang not only led the research team here, but also in other places, there were several groups to study together, and she often ran back and forth.

The creeper almost covered the entire building, and the exterior walls became verdant, and you could even see the water flowing down the walls into a stream.

The inside of the small building was stuffy, the ceiling fan above his head was flickering and turning, and on a large platform where several tables were put together, many senior students were following the experiment, and Teacher Zhang was on the other side of the table, not knowing what was being written.

"Come, come, everyone's worked hard, eat watermelon." When a few people walked in, Gu Tingting put the watermelon on the table, and these students raised their heads, most of them were wearing glasses, looking at the watermelon, they were all puzzled, who they didn't know.

"Hello brothers, this is my brother and sister-in-law, who came to see me, I heard that everyone is working hard, so I bought a few watermelons." Qin Xue said.

Teacher Zhang didn't look back: "Let's eat, let's continue to study after eating, thank you Qin Xue's relatives." ”

After Mr. Zhang finished speaking, he seemed to have just remembered something, and turned back suddenly: "Tingting, Qin Feng, is it you?" ”