Chinese Radar Developments - KLJ series and others


ougoah

Major
Registered Member
Can we come back to the Chinese Flankers please?

@Tam @siegecrossbow and any other participant in that radar conversation. Could you also please continue the interesting discussion on J-10B radar in the radar thread?

I also assumed (due to popular opinion and nothing else) that the J-10B used a PESA radar but it seems that the only real indicator that it might be a PESA are the IFF modules which honestly probably don't prove anything. Does an AESA radar absolutely not have IFF modules designed this way due to whatever engineering compromises?

Anyway, please continue that discussion! ... on the radar thread.
 

Tam

Colonel
Registered Member
@Tam @siegecrossbow and any other participant in that radar conversation. Could you also please continue the interesting discussion on J-10B radar in the radar thread?

I also assumed (due to popular opinion and nothing else) that the J-10B used a PESA radar but it seems that the only real indicator that it might be a PESA are the IFF modules which honestly probably don't prove anything. Does an AESA radar absolutely not have IFF modules designed this way due to whatever engineering compromises?

Anyway, please continue that discussion! ... on the radar thread.

Lots of PESA don't have IFF spread across their face. See the L-15 for example. Lots of slotted array too also don't have IFF spread across the face, like F-16, where the IFF is embedded on top of the nose instead.

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IFF on the face is an engineering compromise. Its likely the IFF system on the J-10B was directly inherited from the J-10A and they don't want to break compatibility until an all new IFF system is introduced to replace it.

On the other hand, every, every example of canted phase array you will find in the West is an AESA.

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latenlazy

Colonel
Based on what? Is there any technical proof that the J-10B array is a PESA? Because of what? Internet momentum?

That diagram is clear as day mentioning a brick architecture for the -10B radar. Modules on AESA are arranged in bricks.

This is what a traditional parallel feed PESA looks like at the edge, using BARS here for the SU-30. Those coils there are the ferrite yttrium phase shifters.

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In contrast the AESA consists of bricks and planks.

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The -10B radar describes a 2 piece brick package on the third line. The -16 radar describes a different brick packaging design. Perhaps for better cooling?

The -10B radar description is also explicit in mentioning T/R. PESA has separate transmit and receive subarrays while in an AESA, an element is both transmit and receive.

It takes some years to develop a military radar, so the timeline around 2009 is about right. Military radars don't advance as fast as commercial and civilian equipment. Phase arrays used in telecom already use a tile based architecture (a) and they make AESA brick designs (b) look like dinosaurs.

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What you see on the diagram with regards to the J-16 and J-20 radars should be more or less same as the diagrams with some up to date refinements. The J-16 radar might be using the 40nm CETIC octacore DSP while the J-20 the 28nm or 40nm CETIC DSP which is not impressive if your idea of modern is 7nm to 14nm. But again, using the stacked chip or Multi Module Chip design can go a long way of compensating for the older fab process, not to mention the larger legacy transistor sizes might be more reliable anyway. The J-10C radar should be more or less along the lines of the J-16 radar but smaller, less elements and less power. Another significant advancement in these years is whether the AESA moved from using Gallium Arsenide for its amplifiers to Gallium Nitride.
It's been long established now that the radar on J-10B (in the picture depicted) is a PESA, not an AESA.

As for JL-10, ultimately we only have rumours to go by, and the rumours have all suggested it is PESA as well.
Tam’s points gets back to something I’ve mentioned a few times before over the years. It’s possible the J-10B radar with the IFF probe is an AESA, but also if the J-10B did end up using a PESA it’s a radar we haven’t seen before. Another possibility is that the J-10B was using the radar with IFF probes and that radar was an AESA, but the J-10C received an upgraded AESA, and whoever originated the information that the J-10B used a PESA simply assumed that if the J-10C was getting a new radar that was an AESA the J-10B’s radar must have been PESA from all the earlier speculations about the IFF probes. After all, we actually never got confirmation over *how* it was determined that the J-10B was using a PESA, and this wouldn’t be the first time that in an information vacuum we backpedaled into conventional understandings built on speculations which became seen as established fact, without hard confirmation.
 

Tam

Colonel
Registered Member
Tam’s points gets back to something I’ve mentioned a few times before over the years. It’s possible the J-10B radar with the IFF probe is an AESA, but also if the J-10B did end up using a PESA it’s a radar we haven’t seen before. Another possibility is that the J-10B was using the radar with IFF probes and that radar was an AESA, but the J-10C received an upgraded AESA, and whoever originated the information that the J-10B used a PESA simply assumed that if the J-10C was getting a new radar that was an AESA the J-10B’s radar must have been PESA from all the earlier speculations about the IFF probes. After all, we actually never got confirmation over *how* it was determined that the J-10B was using a PESA, and this wouldn’t be the first time that in an information vacuum we backpedaled into conventional understandings built on speculations which became seen as established fact, without hard confirmation.

Some guy claimed, "established", that the J-10B radar is a PESA because of the IFF dipoles across its face, similar to the IFF dipoles BARS has its on its face.

That's really poor reasoning. IFF dipoles across the face of an AESA affects the AESA no differently than a PESA because both are phase arrays. The two arrays differ in their internal architecture, not in their steering method, not in their transmit method and not in their receive method. I have not seen any other PESA with IFF dipoles across their face in fact, and even many slotted arrays don't have IFF dipoles across their face such as among many Western designs. The use

The reason for the IFF design is simple. The Chinese copied the IFF design from someone, implemented the system on their older radars, then passed on the IFF system to newer radars, even as their fighter radars evolved from parabolics to slotted arrays then to phase arrays. The old system is retained because they have not devised a newer and more efficient system due to the lack of money and resources, and because the system did work. We know the Chinese approach is conservative, they do not change what is not broken until they have figured out a way to make a more efficient system. Then at some point, they managed to create a more efficient IFF and the dipoles across the face are gone.

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Its the same argument for the dreaded pitot tube you see on the older Flankers that are not J-16s. The pitot tube is an older system that's inherited from the older Flankers and have been there since the beginning, and the J-16 got a new airspeed measuring system. While the pitot tube has some slight interference on the radar system because its on the way, it should not matter if its an AESA, PESA, slotted array, Cassegrain or Parabolic. It should have a slight interference on the radar behind regardless of the radar's internal architecture. The composition and quality of the bandpass radome should have been a stronger factor with regards to the radar's performance, but also that too is independent of the radar's internal architecture. Whether its dark, light, green or blue, the color of the radome has no bearing on the radar's internal architecture unless the radome's color is used as an identification method for a newer jet.


Me thinks its some netizens that are over analyzing things, look hungrily for clues because of the lack of information. Things would have been better if there is some more transparency. In their overthinking things they begin to make wrong connections here and there and so on.

On the L-15, I am going to take what I said back. The slotted waveslot phase array on that picture, is likely to be BARS-130 itself. So it does use ferrite phase shiters. But the feed to the phase shifters may not be using co-ax cables but an interconnecting grid, saving space and weight. The antenna on the BARS-130 is different from the BARS used on the Su-30MKI, as you can see, it uses slotted wave guides while the MKI's BARS uses patch antennas. Somewhere along other versions of BARS were using jigsaw or sawtooth antennas.

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BARS-130 is specifically designed for the Yak-130 jet trainer which is very similar to the Hongdu L-15. So this is what may be installed on the Hongdu L-15 itself. But the Hongdu L-15's radar lacked the IFF probes on the Russian version and that's because IFF systems are not shared internationally because the Russian IFF is for Russian planes and the Chinese IFF is for Chinese planes. For example, the Russian naval radars like Fregat that were sold to China have their IFF removed. So in this case, the Hongdu L-15 has a newer and different Chinese IFF. You don't see the one on the J-10B radar's either, and that's probably because the L-15 already has a newer IFF system than the one on the J-10B prototype (there is a possibility production J-10B batches may already have a newer IFF.)

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