Naval missile guidance thread - SAM systems
- Thread starter Iron Man
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Nothing there in both BARS and IRBIS that show they can move more faster and more flexibly than CAPTOR E and KLJ-7 AESA.
GaN can provide advantage over the TWT , but that still a distinct
The IRBIS-E has a full, two axis rotor, capable to turn mechanically the antenna 120°, and rotate it around is axis, even changing polarity of the antenna.
So, it can follow a target with with the centre of antenna, and mechanically turn away from jammers,and the radar can cover 240° around the aircraft.
The movable AESA radars was an a fixed angle swashplate, rotated in one axis, and more likely not capable to make a continuous full turn .
If they make the angle of swashplate +/-60 ° then it put a good 3db penalty exactly in the front of airplane.
And just to make it clear, example the F-35 radar can cover less than 120 degree in the front of the aircraft - because it is tilted upwards, so the horizontal/down cone will be smaller than for the Irbis-e .
I forget, but the swashplate solution means the radar will change polarity during rotation, just to complicate the efforts about nearly everything : )
So big part of the computer power needed just to compensate the fact the radar return change because of the changes in polarity.
Is it your hobby to argue with everything ?
The IRBIS-E has a full, two axis rotor, capable to turn mechanically the antenna 120°, and rotate it around is axis, even changing polarity of the antenna.
So, it can follow a target with with the centre of antenna, and mechanically turn away from jammers,and the radar can cover 240° around the aircraft.
The movable AESA radars was an a fixed angle swashplate, rotated in one axis, and more likely not capable to make a continuous full turn .
If they make the angle of swashplate +/-60 ° then it put a good 3db penalty exactly in the front of airplane.
And just to make it clear, example the F-35 radar can cover less than 120 degree in the front of the aircraft - because it is tilted upwards, so the horizontal/down cone will be smaller than for the Irbis-e .
I forget, but the swashplate solution means the radar will change polarity during rotation, just to complicate the efforts about nearly everything : )
So big part of the computer power needed just to compensate the fact the radar return change because of the changes in polarity.
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The frequency hopping is performed by the master oscillator. Nothing to do with AESA/PESA. As it has been demonstrated to you, AESA can also have long analog paths. It seems that in your mind the only AESA allowed is a fully digital on both transmit&receive radar. That's wrong. Do you really think that the US AESA radars from the 70s were fully digital with FPGAs and all the other goodies packaged into their TRMs?
I have the impression you just make these things up to support your argument. What you keep saying is a bad idea, has actually been used for quite some time. Check outTam said:
Some promo material:
As I mentioned before, these things can be used to make AESA radars.
With GaAs it was necessary to combine SSPAs in parallel and use power combiners to reach the required power output. This would tank the already relatively lower efficiency. With GaN on SiC power levels went up to a level that combining them in parallel is likely not necessary, or is done on a smaller scale. The efficiency went up to 70% per single SSPA, and operating voltage and temperature more than doubled. All of this allowed for much higher power densities and is one of the important causes of SSPAs replacing VEDs. The US Navy has only now started replacing their VED based SPY-1 radar with SSPA based SPY-6. This tells me that GaAs SSPA based AESA designs were not good enough to meet their requirements.Tam said:
However, if you need even more power, like as much as you can possibly get, then you need to start combining GaN SSPAs in parallel which brings the efficiency down until you reach a point where it no longer scales. Where would you want this much power? In high-power microwave direct energy weapons. VED tubes can generate pulses exceeding 10GW and 1kJ of energy per pulse, enough to burn out and permanently disable enemy electronic systems.
That's also what I used to think, until I googled the subject some more. The big issue is apparently with the SSPA power supply package.Tam said:
Sorry, it has full gimbals.
But this is more of an exception than rule for AESA radars.
Due to the thickness the full range gimbals limiting the size of radar (basic geometry )
The PEASE thinner that AESA (hard to argue I think) means it can be rotated and have big diameter at the same time.
You showed drawings. I showed you actual AESA modules. You can see the AD converters are in the PCB along with the T/R modules. Do you want to remind you and post this an Nth time? In contrast, for the PESA, you have phase shifters underneath the waveguides and antennas, and these have to be connected with long lines to a central unit that has the amp and A/D converter.
Wrong context. Those AESA radars are as big as football fields, work in metric wave and are meant to search for targets in space These radars are so huge you cannot make a PESA out of them as you can imagine the size of the main amp and the length of the feed lines it will entail? With these types of radars, its AESA or bust.
That's a massive oversimplification. You need high voltage on TWT, but you need high amperage on SSPA.
That's not completely correct. The US did develop SPY-3 and SPY-4 with GaAs for the Zumwalt and Ford class carriers, and these radars were planned for future destroyers and cruisers. Then they ran into problems...likely both financial and technical. However by the time they can hope to overcome issues on both these radars, development of GaN radars were also on the way, and it makes so much more economic and development sense to throw all your resources into developing these GaN radars, rather than spend money fixing these GaAs radars.
Do you think the radars on the F-22 and F-35 are GaN? They were GaAs, and so are the replacements radars for the Super Hornet and the F-15EX or something. These will later be replaced with GaN down the line.
Look at the countries that bypassed parallel line PESA development and went straight to early AESA. By what I mean as parallel line feed PESA, I mean like SPY-1, BARS, and Irbis, not spaced PESA like Flaplid or frequency scan sequential line feed planar array like Fregat MAE and SPS-48.
Japan --- see the OPS-24 on the Mursame class destroyers and OPS-20C on the Akizuki class.
Europe --- SAMPSON on the Type 45, Thales APAR on various frigates.
Japan is now moving into GaN with the Asahi subclass. Thales is now offering GaN, like Block II APAR.
Then there is Russia.
Look at the naval phase arrays in the Cold War.
Frequency scan sequential line feed type such as Fregat for search radar.
Spaced feed PESA type like Flaplid for fire control.
You can see both examples on the Kirov and Slava.
You go to the Admiral Gorshkov class.
Rotating Furke S-band radar is a PESA type. Its completely covered so what type of PESA is not clear. But it can be a parallel line or a sequential line feed type. I'm betting more on the parallel line.
However, the jewel of the ship is the Poliment X-band radar, which are these four fixed AESA fixed panels.
So the Russians literally skipped using parallel line feed PESA and hopped straight into an AESA design. The Poliment is meant to engage targets and guide Redut missiles in mid phase. They had developmental issues, so by the time they commissioned the ship, the Russians already have second generation AESA on Project 20385 heavy corvettes like below. Picture below conveniently shows both Gorhskov class and Gremyaschy class. You can see all four types, Furke, Poliment, and the Zaslon (they gave it the same name as the radar for the MiG-31, so issues with Googling it.) You can also see, from the newer ship design, the S-band Furke PESA is no longer being used, replaced by four S-band AESA panels instead and which along with the four X-band AESA, constitutes for a dual band system here.
Look the Russians are also putting AESA on their helicopters.
Oh look at that, its on the new Pantsir model too.
Note that one of the AESA modules I have shown you is one by Phazotron and dated around 2007. So even that early, you have the Russian developing Quad TR module with SSPA and FPGA. The FPGA is Xilinx, which is American but that's for prototyping, and you can substitute that with another FPGA or an ASIC in the final products down the line. At this point now, the Russian defense industry is now having heavy momentum in developing AESA systems, including GaN ones.
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I saw it, I am not denying it. What I don't get is why are you fixated on this one implementation of AESA? This isn't the only way to build AESA radars. Just because a radar is AESA does not mean it has this one particular architecture that you keep reposting all over.
Why do you keep making things up??? Have you ever heard of Cobra Dane? A PESA radar built a few years before the AESA PAVE PAWS, with antenna diameter actually 30% larger than PAVE PAWS. Oh no, but that cannot possibly be done ... brain melt.
Oh, and I am still curious to hear you answer to the question posted by @Anlsvrthng:
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What do you mean one implementation of AESA? This is currently, for all practical purposes, the ones you see for aircraft and naval radars.
Can you provide an example of an AESA that would have a long feed line to its PESA equivalent for the same mission purpose?
Oh you got me there.
Then again, what makes you think Pave Paws is going to have longer feed lines compared to Cobra Dane?
Description of Cobra Dane seems more of a hybrid AESA-PESA however as it doesn't seem to have a central transmitter, but set of transmitter groups.
"The installation comprises a total of 12 transmitting groups, each incorporating eight of type QKW-1723 using ring-loop slow-wave circuit, each with a peak power of 175 kW and an average power of 10.5 kW. "
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Let me summarize what I've learned from the exchange we've had in the last week or so, as it relates to the difference between PESA/AESA, and how AESA radars in general are constructed.
An AESA radar can have just one transmitter, just like a PESA radar. The key difference is, that the high power amplifiers (HPA) are distributed throughout the antenna in an AESA architecture. Whereas, in a PESA radar, the HPA are not part of the antenna. Similarly, on the receive side the low noise amplifier (LNA) is distributed across the antenna in an AESA architecture. Whereas, in a PESA radar, there is one LNA that receives the signal input from the beamformer, typically per sub-array. Apparently, some modern PESA radars introduce separate receive channels with the LNAs inbuilt into the array, just like an AESA radar, equaling their advantages on the receive side. Examples proposed: Russian Bars/Irbis radar, American SPY-1 radar.
On both the transmit and receive side, AESA radars, just like PESA, started off using analog wavefront generation and analog beamforming. Ever since, there has been a steady trend towards going more digital and ever closer to the antenna, with the end goal being a digital array radar (DAR). Even though this trend appears to be associated primarily with AESA radars, I think it is to a large degree orthogonal to whether a radar is PESA or AESA. I say this, because there are exist partial implementations of the concept, such as digital beamforming on the receive side that both PESA and AESA can perform. Ditto for WFG. However, a true DAR does require HPAs to be part of the antenna, so AESA is the only right architecture to achieve this.
Some misconceptions that have been shown false, are:
- PESA must have one transmitter
- AESA has as many transmitters as there are TRMs.
Both systems can have just one transmitter. There are PESA that have 8 or more transmitters: SPY-1 and Cobra Dane to name the examples mentioned in the discussion here.
"Multiple beams": it is commonly advertised that a big advantage of AESA is forming multiple transmit beams. However, what seems to be overlooked or misunderstood, is that both PESA and AESA can and routinely do form multiple receive beams. From what I could gather, the common practice appears to be to send out one beam on transmit and then decompose it into smaller beams on the receive side, through either analog or digital beamforming. On my todo list is to understand how digital beamforming on the transmit side works. Would appreciate if someone can offer pointers.
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