J-20 5th Gen Fighter Thread VIII

Gloire_bb

Colonel
Registered Member
Uhh isn’t the AN/APG-77 about the same peak power as the N035?
Peak? Yes. If you want to work, however, there's a very hard cooling cap, as you need to deal with a lot of inconvenient heat. For PESA it's relatively straightforward, you have single(+-) emitter - cool it.
For any AESA (and AESA aircraft) it's a lot of trickstery, and caps are rather low unless you want to explore technical feasibility of liquid state TRMs.
Moreover, as a rule of thumb, fighter AESAs aren't really meant to work at full power in the first place. Beaming like a pole on frequency diagram isn't exactly a modern fighter way, nor is radiating narrow 12x12 patch of sky.

Maybe it'll be possible to run Gan on sic AESAs on 6th gen fighter aircraft at hundreds of kW(for now it's big AWACS only). But frankly speaking, i'm almost sure huge boom in both power gen and cooling capability in next generation of aircraft will be routed to other places.

p.s. come to think of it, didn't realise before that powerful GaN EW pods should logically come with very significant flight envelope limitations whenever active. As you'd need to have enough air cooling flow while overcoming all that additional RAT drag.
 

tphuang

General
Staff member
Super Moderator
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Registered Member
I mean with GaN on SiC technology where it is, I don’t understand why people think this is some mythical technology. The liquid cooling and high voltage platform is widely used in new 5G base stations.

6th gen aircraft peak power consumption will easily get to MW level.

The tech is there for J20A and all the big shrimps have been raving about it for a month now
 

siegecrossbow

Field Marshall
Staff member
Super Moderator
I mean with GaN on SiC technology where it is, I don’t understand why people think this is some mythical technology. The liquid cooling and high voltage platform is widely used in new 5G base stations.

6th gen aircraft peak power consumption will easily get to MW level.

The tech is there for J20A and all the big shrimps have been raving about it for a month now
It’s because the U.S. and other NATO countries haven’t successfully implemented one for fighter aircraft yet.
 

BoraTas

Major
Registered Member
I suspect the said 100-200% range increase has caveats. Even without the accounting for absorption, a doubling of the range requires 16x the average power. That is simply not possible with going to SiC from a Si substrate. I used AI to list several RF X-band HPA amplifiers from the market. It appears like GaN-on-SiC ones are about 2 times more powerful, not 16! So I think there is something else ongoing with the massive range increase. I think it is a networking trickery. If different J-20s are tasked to scan different pieces of the sky, each can scan their patch using a longer dwell time. Which would increase the range. Then they would fuse the data.
 

siegecrossbow

Field Marshall
Staff member
Super Moderator
I suspect the said 100-200% range increase has caveats. Even without the accounting for absorption, a doubling of the range requires 16x the average power. That is simply not possible with going to SiC from a Si substrate. I used AI to list several RF X-band HPA amplifiers from the market. It appears like GaN-on-SiC ones are about 2 times more powerful, not 16! So I think there is something else ongoing with the massive range increase. I think it is a networking trickery. If different J-20s are tasked to scan different pieces of the sky, each can scan their patch using a longer dwell time. Which would increase the range. Then they would fuse the data.
That’s my suspicion as well. They basically have a piece of sky assigned for each aircraft and form a big picture from mosaic of information. This is going to be useful when force multipliers are targeted.
 

latenlazy

Brigadier
I suspect the said 100-200% range increase has caveats. Even without the accounting for absorption, a doubling of the range requires 16x the average power. That is simply not possible with going to SiC from a Si substrate. I used AI to list several RF X-band HPA amplifiers from the market. It appears like GaN-on-SiC ones are about 2 times more powerful, not 16! So I think there is something else ongoing with the massive range increase. I think it is a networking trickery. If different J-20s are tasked to scan different pieces of the sky, each can scan their patch using a longer dwell time. Which would increase the range. Then they would fuse the data.
I think that magnitude of range increase isn’t just from total power output but a combination of better power output, better noise floor, and better sustained operational parameters from much better thermal and voltage breakdown characteristics.
 

tphuang

General
Staff member
Super Moderator
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I think that magnitude of range increase isn’t just from total power output but a combination of better power output, better noise floor, and better sustained operational parameters from much better thermal and voltage breakdown characteristics.
Exactly, if you actually look at theoretical power density of GaN-on-SiC material, we are still quite far from getting to that point. Main constraint is cooling and power generation.
 
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