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Reply With Quotelooks like a deja vu
see PESA vs. AESA
also, I don't know who copied what, but I'm pretty sure, that the both sides had the blueprints of the 'other' radar, thanks to intelligence
I was debating with my (Russian) friend about radars. He said that the MiG-31, which is a Phased Array Radar, was copied by the US and is basically the AESA and that Russia fielded an AESA long before the US. I might not be an engineer but I can tell that they aren't the same thing. But is there any expert here that could clarrify this? Thanks
looks like a deja vu
see PESA vs. AESA
also, I don't know who copied what, but I'm pretty sure, that the both sides had the blueprints of the 'other' radar, thanks to intelligence
Last edited by Injecteer; 27 Dec 05, at 13:12.
Those are the same things? Oh, I didn't know that. We learn something new everyday.
>>Those are the same things?
they make use of the same phased arrays theory, and the way they are built may differ, but the end-users do not care of it, and we can not get the blueprints of the things. That's why here we can rely only on some basic phisical laws
The Mig-31 phased array radar is definitely passive.
As I understand it AESA is currently far more desireable then either PESA or modern phased radar arrays.
The main operational benefit of AESA are its far more reliable then previous conventional radar technoligy. An AESA radar arrays have no moving parts and are generally made up of hundreads or thousands of TR modules, unlike a convertional radar which uses a single tube the AESA array can suffer a loss of up to 10% of its TR modules and still remain operational. On current fighters its estimated an AESA radar should last a little over 5 years before it needs its arrays replaced.
The next major benifit is the AESA capability for digitially controlled beamstearing.
This allows the radar to sweep or pulse in unpedictable and difficult to detect patterns and can continually change power output levels to also help reduce the chances of an intercept. Unlike conventional radars which actually have to move in order to sweep the AESA is electronic making its sweeps signifcantly faster far more unpredictable and more precise.
Digitially controlled beamstearing is also allowing the radar to function as a electronic weapon capable of focusing on a single target and jamming or distrupting any unshielded electronic componets.
And on a final note the AESA radars also have extremly low sidelobes versus PESA or conventional mechanically steers radar arrays.
In short the AESA radars have all of the benefits and superier capabilities of an modern active radar array with chances of detection closer to that of passive radar arrays while not having any of their disadvantages. The AESA would also be nearly impossible to jam.
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Ok now to the downsides to AESA radars versus the others.
The big one is AESA radars are extremely expensive to manufacture early versions costed upwards of $2,000 US per module with radars being made up of anywhere from 1,000-1,800 modules when compared to the other competing radar systems AESA is dramatically more expensive.
The other big disadvantage is power consumption and the resulting heat, AESA generate alot of heat the U.S module uses a polyalphaolefin (PAO) coolant similar to a synthetic hydraulic fluid to cool the array. The reliability of the GaAs MMIC that the array uses is significantly impacted by the temperature they run at.
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AESA simply makes to much sense not to use, I figure eventually everyone will be using it but not until it comes down alot more in price.
Last edited by canoe; 30 Dec 05, at 06:47.
Sorry figured I'd break this part off my previous post and answer your russian friends point. A direct comparison between AESA and a phased radar array is this.Originally Posted by The_Burning_Kid
I was debating with my (Russian) friend about radars. He said that the MiG-31, which is a Phased Array Radar, was copied by the US and is basically the AESA and that Russia fielded an AESA long before the US. I might not be an engineer but I can tell that they aren't the same thing. But is there any expert here that could clarrify this? Thanks
Phased radar arrays have been around for over 20 years, they physically look similar to AESA and PESA radars but are infact far more primative. Although he is somewhat correct in that AESA was a logical next step from phased radar arrays. The U.S has wide use of phased radars on things like warships and even patriot missile batteries.
A phased radar array is made up of a bunch of antenna receiver modules and uses a single high power electronically steered transmitter. The return is then processed by a single processor.
An AESA radar takes the concept of using an array antenna a step further. Instead of shifting the phase of signals from a single high power transmitter AESA employs a grid of hundreds of small modules that are linked together by high-speed processors.
Each TR module has its own transmitter, receiver, processing power, and a small antenna on top. The TR module can be programmed to act as a transmitter, receiver, or radar. The TR modules in the AESA system can all work together to create a powerful radar, but they can do different tasks in parallel, with some operating together as a radar warning receiver, others operating together as a jammer, and the rest operating as a radar. TR modules can be reassigned to any role, with output power or receiver sensitivity of any one of the subsystems defined by such temporary associations proportional to the number of modules.
AESA provides 10-30 times more net radar capability plus significant advantages in the areas of range resolution, countermeasure resistance and flexibility. Since the power supplies, final power amplification and input receive amplification, are distributed, MTBF is significantly higher, 10-100 times, than that of a passive ESA or mechanical array.
Last edited by canoe; 30 Dec 05, at 06:53.
first of all, I've got to tell, that 'PESA' is a name invented and used solely by the AESA-loving guys
If U take a look at, for example, any russian radar info, specs, etc, U will NOWHERE encounter a word 'PESA'. Instead they reference the device as 'Phased Array Radar/Grid'.
So, I tend to think, that this 'AESA/PESA' naming is a pure marketing trick, because something 'Active' sounds inherently better than the same thing, which is 'Passive'
exactly the same can be said about ANY PAR
1. Any 'real' PAG provides electronical beamsteering without moving parts. Exceptions here could the flat antennas for the use in a camping-trailer. I assume, that they are also arrays, but the phase-shifts are 'hard-coded' on the factory, so no steering is possible any more
2. the frequencies and patterns/modes of erradiation depend rather on the transmitter capabilities, and not on the radar, whatever type it is.
3. a PAG really provides a way faster and more accurate beam steering, and AESA here is on top, but the difference in speed between it and other PAGs is not that big.
any directed antenna can be used as an energy weapon and here PAGs are not exceptions.
wrong! a usual parabolic antenna has VERY small side-leaves. The bigger the diameter of an anena is, the narrower the main leaf is and the smaller side-emittions are.
Another thing to add here is, the gain-quotient. the PAGs' gain is not something exceptional, comparing to parabolic antennas. Again, the main advantage of a PAG is the ability to steer faster, more precise and without moving parts.
Therefore, the range of detection for the AESA would not exceed a lot the one of a parabolic antena.
dream on
the responsibility to withstand jamming has rather the receiver, and not the antenna. The only thing antenna can do is to reduce the sidelobes and narrow the main leaf.
It is up to the signal transmitter/receiver to select the pattern of radiation and choose the anti-jamming techniques.
and all those 'high-speed processors' are linked to the central CPU, like in any other PAG. Otherwise, it would be impossible to build a whole picture to show on a screen.
or a coffee machine
actually each TR can perform the follwoing functions:
1. be powered at 100% --> Emit
2. be powered at 1% --> recevie
3. not be powered --> dead
nothing more, nothing less. 'Radaring' is just a combination of points 1 and 2.
I don't think they work independently. The reason is simple: each of the elements is very 'weak', and that's why they are bundled together to form a system, who's resulting performance would be the sum of all it's elements.
So, although it's possible to steer individual 'pixels' of a PAG, it's rather inpractical and would require more processing power.
sorry, there's no such a mode of a fighter plane's radar to jam something. Actually it's a role of AWACS-like plances (not sure, what the name is... a jamming plane
Sorry this is alot to answer all at once.
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first of all, I've got to tell, that 'PESA' is a name invented and used solely by the AESA-loving guys
If U take a look at, for example, any russian radar info, specs, etc, U will NOWHERE encounter a word 'PESA'. Instead they reference the device as 'Phased Array Radar/Grid'.
So, I tend to think, that this 'AESA/PESA' naming is a pure marketing trick, because something 'Active' sounds inherently better than the same thing, which is 'Passive'
exactly the same can be said about ANY PAR
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Active Electronic Steered Arrays/Passive Electronic Steered Arrays and phased arrays as used by the U.S and Europe (I'm less familure with Russian technoligy) are all different technoligies.
Phased radar arrays are very old and unlike either PESA or AESA, it has a single high powered transmitter and antenna 'modules' .
The main difference between PESA and AESA is, PESA arrays have a single transmitter/receiver and use a phased shifter to beamsteer, AESA actually has two transmitter/receiver modules and thus doesn't need to share a single transmitter/receiver nore use phase shifting at all. A good description about the differences between PESA and AESA can be found at this website:
http://www.memtronics.com/files/PAPER_RAD99a1.pdf
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1. Any 'real' PAG provides electronical beamsteering without moving parts. Exceptions here could the flat antennas for the use in a camping-trailer. I assume, that they are also arrays, but the phase-shifts are 'hard-coded' on the factory, so no steering is possible any more
2. the frequencies and patterns/modes of erradiation depend rather on the transmitter capabilities, and not on the radar, whatever type it is.
3. a PAG really provides a way faster and more accurate beam steering, and AESA here is on top, but the difference in speed between it and other PAGs is not that big.
any directed antenna can be used as an energy weapon and here PAGs are not exceptions.
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Ok:
1. Yes, however only with a single transmitter.
2. That answer doesn't make any sense to me, yes it depends on the transmitter capabilities but AESA combines thousands of transmitters where as a phased array generally has a single transmitter. The advantage to having thousands of transmitters capable of operating independantly or in parrellel when sweeping or pulsing for targets I would assume is pretty obvious.
3. In terms of single sweep yes AESA doesn't have any significant advantage over most other modern electronic steered radars. However AESA can distribute the load over its modules and do hundreads of short range sweeps at the same time to reduce the time it takes to get a complete return.
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wrong! a usual parabolic antenna has VERY small side-leaves. The bigger the diameter of an anena is, the narrower the main leaf is and the smaller side-emittions are.
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Ok this counters what I understand about the modulized active steered arrays but I'll save this debate for another post below somewhere.
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Another thing to add here is, the gain-quotient. the PAGs' gain is not something exceptional, comparing to parabolic antennas. Again, the main advantage of a PAG is the ability to steer faster, more precise and without moving parts.
Therefore, the range of detection for the AESA would not exceed a lot the one of a parabolic antena.
---
Your correct, however virtually all electronically steered arrays have much higher range resolution meaning they can actually see things at the edge of their detection range far more clearly. Whereas mechnically steers arrays usually have a pretty heavy loss in resolution as targets get closer to its maximum range.
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the responsibility to withstand jamming has rather the receiver, and not the antenna. The only thing antenna can do is to reduce the sidelobes and narrow the main leaf.
It is up to the signal transmitter/receiver to select the pattern of radiation and choose the anti-jamming techniques.
---
Your missing the point, modern jammers have to identify the radar signal it needs to jam then counter it, thats very difficult to do when the outbound signal is constantly changing and/or you have multiple signals to jam at the same time. Keep in mind AESA doesn't have a predictable sweep, nore does it have to do one sweep at a time, it can do multiple sweeps simulatinously all at difference frequencies. Modern phased arrays can't do all this.
With modern diginal technoligy its easy to filter out garbage background noise from your actual signal, the issue becomes when someone starts spoofing your own transmitter or interfering with the specific frequency your transmitter is using, this problem can be reduced significantly if your radar array is using a wide spectrum of frequencies and sweeping with multiple groups of arrays.
Ok rather then replying to all this I'm just going to post a link this time.
http://kuku.sawf.org/Emerging+Technologies/2667.aspx
One point I will make is your absolutely correct about the AESA array require huge amounts of processing power in order to do all this.
Look under the "Common Integrated Processor (CIP)" section.
http://www.globalsecurity.org/milita...2-avionics.htm
and all those 'high-speed processors' are linked to the central CPU, like in any other PAG. Otherwise, it would be impossible to build a whole picture to show on a screen.
or a coffee machine
actually each TR can perform the follwoing functions:
1. be powered at 100% --> Emit
2. be powered at 1% --> recevie
3. not be powered --> dead
nothing more, nothing less. 'Radaring' is just a combination of points 1 and 2.
I don't think they work independently. The reason is simple: each of the elements is very 'weak', and that's why they are bundled together to form a system, who's resulting performance would be the sum of all it's elements.
So, although it's possible to steer individual 'pixels' of a PAG, it's rather inpractical and would require more processing power.
sorry, there's no such a mode of a fighter plane's radar to jam something. Actually it's a role of AWACS-like plances (not sure, what the name is... a jamming plane
Last edited by canoe; 30 Dec 05, at 14:06.
AFAIK, the russian terminology includes the name of the principle, namely "phase shifting". This is how any PAG, A-/P-ESA and alike works.
How it's achieved is not said. It may be mechanical swithes, or electrical, or electronical, or quantum, doesn't matter! the russian naming reflects only the principle behind.
So, I would never assume, that what is called in Russia now as 'Phased Array Radar' is the same thing, created 20 years ago
1. the antena itself has ABSOLUTELY nothing to do with the signal source! it can be made of a single module, or have hundreeds of them. It's wrong to bind an antena type to the contruction of a recever/transmitter.
2. The pdf U linked looks like an intro from the book "Phase array grids for dummies"
Arrghh! NO! the AESA, as any other antena has a SINGLE 'black box' -- a signal source -- operating at a single moment of time. What U call 'thousands of transmitters' refer to elementary antennas, which emmit or receive EM-waves. But still the signal gets processed outside of them.
no. the AESA as any other PAG works as a SYSTEM, meaning that it emmits and steers a SINGLE beam, but it's doing that so damn' fast (in a matter of ms), that the end user has a feeling, that he has many radars
hmmm.. Range resolution is not a feature of an antena, but it's a complex measure, where the major role plays the signal processing unit(s) and the patterns it's using. Antenna on it's own can't do a lot here.
keep it simple
a jammer emmits so damn strong and broad-band signal, that it doesn't need to track radiation changes of each enemy's radar. It doesn't care about an individual signal at all!
Well, in general, each antena has it's fixed SNR (signal-to-noise ratio) for each given freq. Any PAG as well as AESA is no exception. On the way to increase the SNR, the antena turns into the bottleneck, and the SNR must be increased somewhere else, i.e. by improving the singal source, or using different radiation patterns.
those links are even more "for dummies", than the 1st link U posted
an piece of the http://kuku.sawf.org/Emerging+Technologies/2667.aspx:
"Planar array antennas, like dish antennas, are also mechanically steered but they use a flat rather than concave receiver to gather the reflected radar energy."
muhaha! He shouldv'e compared it to his mobile phone's antenna
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1. the antena itself has ABSOLUTELY nothing to do with the signal source! it can be made of a single module, or have hundreeds of them. It's wrong to bind an antena type to the contruction of a recever/transmitter.
2. The pdf U linked looks like an intro from the book "Phase array grids for dummies" I wouldn't take everything from there seriously.
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"http://www.memtronics.com/files/PAPER_RAD99a1.pdf"
Ok first off regarding the first website is a very credible souce, no its not the electronic engineering textbook I had in university but it does do a reasonable job of explaining the differences between AESA and PESA in laymens terms. It is however a credible source. References for the paper are sourced at the bottom and its written by well known academics.
Global security is also a very reliable source of information hence why most of the defence community visits it. I'd imagine almost everyone in this forum is already familure with it. It does provide some numbers and general information but no it doesn't contain schematics for the onboard processors.
http://kuku.sawf.org/Emerging+Technologies/2667.aspx
And yes this site is more media oriented then scientific, I posted it as to provide information about what the difference is between the arrays to save myself having to type it all out again.
And the antennas array does have to do with the signal source when 'it is' the signal source. PESA and AESA are just terms assigned to types of technoligy, similar to how you have standards memory and DDR memory for your computer. Their related but are different. Both are related but work slightly different thus the different names. And both are a step above older phased array radars, hence why everyone is switching to them.
Basiclly I'm going to cut this off because I don't see it going anywhere but to point out the differences between AESA, PESA and phased arrays. Maybe they call them something else in Russia and thats why you think their all the same thing but here it goes one last time.
Definitions simplified:
- Phased arrays developed quite some time ago have large numbers of antenna modules and a single (usually electronically steered) transmitter.
- Phased arrays lead to the development of passive electronically steered arrays which incorperate a phased shifter and a transmitter/receiver into each module of the array thus no longer relying on a single transmitter for all the antenna receivers.
- Active electronically steered arrays took the next step in development and shed the phase shifter and incorporated a second transmitter receiver module.
The different diagrams of the different modules are available on first website you mentioned. If you go into any university in North America or Europe the different technoligy goes by those terms. Maybe in Russia there all called phased arrays I have no idea.
Last edited by canoe; 30 Dec 05, at 17:26.
Phased array radars, or PAR's in Russian terminology are the same basic technology as what are commonly referred to as PESA or passive electronically steered arrays in western terminology. There are some PAR's that are mechanically steered, but even those usually use a combination of mechanical and electronic steering. The microwave source is a TWT or traveling wave tube. PESA radars DO NOT use individual T/R modules in the elements- they use passive ferrite phase shifters for steering the beam, and T/R is handled by the TWT. AESA sets use monolithic microwave integrated circuits- MMIC's. MMIC's DO have T/R modules built into each element. MMIC's also have processors built onto each element.
The Russian version of AESA is usually refferred to as APAR or AFAR, for active phased array radar. Phazotron has built a bench model of one of these, but Russia does not have the ability to manufacture the MMIC's in quantity needed to build a production AESA set at this time.
Both types are beam agile. PESA sets are not frequency agile, because the frequency is set by the TWT. AESA sets are frequency agile, because the MMIC controls the frequency electronically. AESA sets have much lower side-lobes than any other type, PESA, Slotted Planar, or conventional. AESA is superior at multi-tasking, and handle simultaneous EW, communications, as well as traditional radar functions. PESA sets are jammable, by saturating the TWT. AESA sets are not nearly as jammable, because they are frequency agile and can use LPI modes.
AESA is more reliable, has much higher MTBF, and graceful degradation. Current 2nd generation AESA sets have sealed antenna units that are replaced as a single LRU. The TWT tubes in PESA radars degrade over time, and have to be replaced frequently. A single TWT failure renders the set inoperable, while AESA sets can lose many elements without significantly effecting performance. MMIC's need external cooling though, so there is an added complexity that PESA does not require.
Pretty much everything canoe has said here is correct. Injecteer, you are the one that needs to do some better research.
Last edited by highsea; 30 Dec 05, at 21:08.
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