KJ-600 carrierborne AEWC thread

[Inst]

About the dropping nose, I'm suspecting the H-600 is designed to feature bistatic radar; i.e, the nose radar and the upper radome function in tandem; as the nose radar is at a different location than the upper radome, part of the shaping signal deflection is defeated very slightly by the nose radar being able to absorb deflected signals.

Not sure how well it'd work, from what we know about the E-2D and KJ-500 radomes, the approximate size of the radome aperture should be around 5 square meters, but the nose radar is about B-1B-sized, so about 1.25 square meters. The smaller aperture may defeat attempts to run bistatic radar.

Another key difference between Chinese AESA AEW&C and American AESA AEW&C is the radome design; the E-2D features a rotating bifacial AESA, while Chinese AESA to date have been, excepting the static bifacial "beam" antennas we've seen, static trifacial. This means that, for the same radome size, the E-2D is going to be more powerful, but Chinese AESA have typically featured a larger radome; on my measurement of KJ-500, the radome face is identical.

There's a few trade-offs in having rotating vs non-rotating radomes. First, trifacial radomes are going to be larger, and involve more modules than rotating bifacial radomes, increasing cost as well as drag, and by increasing drag, reducing endurance. On the other hand, however, trifacial radomes do not rotate and thus have fewer points of mechanical failure.

Last thing to note is, that if my estimates of radome aperture are correct, if we accept that the Chinese state-of-the-art J-11 AESA can hit 400-450 km of detection range vs 0 dBsm, scaling it up to AEW&C aperture implies a radome with a detection range of 1032-1161 km. Vs -30 dBsm, as I expect the J-20 and F-35 to be in the UHF-band, this comes out to an approximate detection range of about 184-206 km. If GaN modules are used, and achieve at least a 3x increase in power (4x modifier), the detection range jumps to 400 km; i.e, with J-20s running long-range sentry jobs, the J-20's EODAS should be able to pick up the F-35 relatively early with the AEW&C telling it where to look and get a firing solution before the F-35 is close enough to launch AIM-120s for intercept.

Edit:

The diagram refers to the nose element as "气象雷达", or meteorological radar. Doubtful, given the large size, but the CG is most likely just a fanboy image anyways.

 

[Hyperwarp]

I thought dropping the nose was due to visibility reasons?

 

[Inst]

The big question I have about the H-600 is what exactly is the radome radar? I.e, with the E-2D, the United States opted, uncharacteristically, for a PESA radar, claiming that AESA technology was not mature enough.

There's two ways to take this statement.

First, take the Americans at face value. As veroth kindly explained a long while back, antenna count in ESA is a function of aperture and wavelength; antennas are designed as half wave dipoles relative to a frequency and you can't scale them down and receive greater reception for a given frequency. For the E-2D to operate at 600 mhz, the E-2D would only have 75 modules per face. A T/R module at the E-2D size would have to generate about 1.33 kilowatts of peak power, by itself, to match the power density of a 1 meter diameter Gallium Arsenide radar, which is an order of magnitude higher than even the best individual T/R modules to date for UHF. I.e, the technology isn't there. Using phase shifters with a central magnetron manages to get around this problem.

Second, assume that PESA is actually superior to AESA when you get into AEW&C applications. Performance-wise, the main difference between AESA and PESA is that PESA uses magnetrons external to the antenna modules to generate power, then uses a phase shifter to change frequencies. This results in roughly a 2.8 dB difference, or equivalent to 17% range difference between AESA and PESA for the same generated power. And PESA also has a beam focus issue; i.e, AESA can create narrower and more focused beams, creating greater effective power for the same wattage. Moreover, because PESA uses a central signal generator, it can't achieve LPI modes, which is why AESA is preferred on Western fighter radars. But on AEW&C aircraft, you can just power through the efficiency loss by using a larger and more powerful magnetron, unconstrained by T/R module limitations.

Applied to the H-600, what you get instead is a few hypothesis.

First, the H-600 has managed to solve the technical problems the E-2D could not; i.e, it's a UHF radar with high individual output energies. To what degree is debatable; it is possible that even with GaN, the H-600 might only be able to match older Gallium Arsenide AESAs in power output, or, the H-600 might have figured out how to properly bin exciters and generate module outputs on the orders of tens of kilowatts.

Second, the H-600 did not manage to solve these technical problems, but uses GaN AESA. This means that the H-600, unlike the E-2D, operates in the L-band as opposed to the UHF-band like the E-2D. This means its counter-stealth potential is far lesser, but against non-stealth aircraft, it is far more capable and might be able to simply burn through a stealth aircraft's absorption.

Third, the H-600 did not manage to solve these technical problems, and like the E-2D uses PESA.

If the H-600 ends up using AESA, it does gain the advantage of having LPI modes. If it has LPI modes, the advantage becomes that it becomes much harder for stealth aircraft to passively detect its emissions, albeit losing significant range in doing so.

 

[asif iqbal]

Please avoid such long posts with so many questions

I click here for a update and see this

 

[Lethe]

There's a few trade-offs in having rotating vs non-rotating radomes. First, trifacial radomes are going to be larger, and involve more modules than rotating bifacial radomes, increasing cost as well as drag, and by increasing drag, reducing endurance.

Drag? Pretty sure China has mastered the exotic art of building radomes…

 

[Inst]

All other factors being equal (fineness ratio, no aerodynamic effects, etc), a larger object generates more drag than a smaller object, and even if you have a larger object with the same drag, you can have a larger effective radar aperture by going bifacial instead of tri-facial.

There's a few interesting aspects, however.

First, once you scale up to the 600 mhz (30 cm per antenna size), you actually have relatively few generating elements. One way might be to do hybrid PESA, as in the Irbis-E. In the Irbis-E's case, you have multiple magnetrons instead of a single magnetron as with conventional PESA. Scaled up to the H-600, you could have instead 75 small magnetrons with 1.3 kw or higher individual power output, or perhaps 5, 25, with multiple modules in a checkerboard pattern slaved to a specific magnetron. This gives you greater beam flexibility, but still suffers from the same transmit efficiency loss as conventional PESA, and depending on system staggering, you may not gain the same fineness of beam as with an AESA implementation.

Second, from the image presented, we are not seeing a conventional trifacial antenna, but something that is somewhat quadfacial. What we could be seeing instead is some kind of new antenna configuration, wherein each side of the module has its own receive equipment, so that the aperture size could be even larger.

In either case, I give the H-600 a fairly good chance of being able to detect American stealth aircraft at sufficient range that a sentry stealth fighter could IR-lock the assailant before it can launch missiles at the H-600.

 

[2=GT]

 

[asif iqbal]

Come on KJ-600 AWACS

its been a long time

 

[Orthan]

Is this in zhuhai 2018? well, i have never heard about KLC-7. What do you think of this? an abstract carrier-based AEW, just to show how one could look like, or is this a real model in development?

 

[Hendrik_2000]

Is this in zhuhai 2018? well, i have never heard about KLC-7. What do you think of this? an abstract carrier-based AEW, just to show how one could look like, or is this a real model in development?

It is not abstract. The on board Carrier program has been going on for a number of year now Only now the release the picture and designation of the KJ 600 radar

From Zhuhai show via Henri K
The radar "Eye of the Silk Road", with AESA antenna and dedicated to AWACS, carries the reference KLC-7. Unlike the KJ-2000 and KJ-500 which have 3 fixed flat faces each covering 120 °, this new radar requires the rotation of its radome.

#2026Hendrik_2000, Nov 4, 2018

Here is the video