How effective are modern radar systems at detecting low-RCS targets?

Burke095

New Member
The AN/APS-145 radar carried by the E-2C Hawkeye operates in the UHF range, apparently around 445 MHz. This puts it well below the 2 GHz limit below which "nothing is invisible." Does this mean that the E-2C is capable of detecting stealthy targets?

Additionally, the E-2D will add an AESA radar, which should improve its ability to detect small targets (for example, the F-15Cs AESA radar is able to detect small cruise missile targets because of its electronic scanning).

These features, combined with the very high power of an AEW&C system, should give the E-2C a very good capability to detect low-observable targets, and the E-2D an even greater ability to do so. Does this sound plausible?
 

Bonza

Super Moderator
Staff member
The AN/APS-145 radar carried by the E-2C Hawkeye operates in the UHF range, apparently around 445 MHz. This puts it well below the 2 GHz limit below which "nothing is invisible." Does this mean that the E-2C is capable of detecting stealthy targets?

Additionally, the E-2D will add an AESA radar, which should improve its ability to detect small targets (for example, the F-15Cs AESA radar is able to detect small cruise missile targets because of its electronic scanning).

These features, combined with the very high power of an AEW&C system, should give the E-2C a very good capability to detect low-observable targets, and the E-2D an even greater ability to do so. Does this sound plausible?
Define "low RCS". That's the first problem, there's not a concrete definition of the target size so a yes/no answer is impossible. The other problem is that the RCS of a given object will be different from different angles and so on, so again the answer becomes more subjective.

In addition there is a difference between detecting an object, and tracking an object, and obtaining a useful firing solution for an object. You might detect a low-RCS aircraft briefly, but that doesn't mean you will be able to track it consistently, let alone aim a system at it that allows a meaningful offensive action towards that aircraft.

That's the issue with saying whether or not a given radar set can detect "stealthy targets". There are many claims of that kind of capability at present, but without a clearly defined understanding of the level of RCS reduction and the specific context of the situation it's very difficult to know how much of these claims are hyperbole. I hope that gives you a decent idea as to the topic, I know it isn't much of an answer in the positive/negative sense, but it's a less straightforward topic than many of the claims you hear about various radar/weapon systems would have you believe. Others here with a better understanding of the topic may be able to give you a better answer too. Cheers.
 

koxinga

Well-Known Member
The radar first has to generate plots from the radar video. From the plots, tracks can be formed.

Between all these processes, a lot can be lost or filtered out. The front end might operated on a frequency which a LO target can be possibly 'detected' but whether there is sufficient data from the raw video to form targets is another matter.
 

gf0012-aust

Grumpy Old Man
Staff member
Verified Defense Pro
The radar first has to generate plots from the radar video. From the plots, tracks can be formed.

Between all these processes, a lot can be lost or filtered out. The front end might operated on a frequency which a LO target can be possibly 'detected' but whether there is sufficient data from the raw video to form targets is another matter.
there is no "video" in track management

track data is like a high fidelity CSV file

unless you can sustain 3 dimensional tracking across complex conditions, then all you have is a 2 dimensional plot - plotting is insufficient
 

protoplasm

Active Member
there is no "video" in track management

track data is like a high fidelity CSV file

unless you can sustain 3 dimensional tracking across complex conditions, then all you have is a 2 dimensional plot - plotting is insufficient
The operator may well have an "idea" that there is something out there, but isn't likely to have a firm fix on the exact location in 3D space at any specific point in time. If you don't have that, there is nothing that can be specifically targeted, hence you can't direct a weapon against it.
 

gf0012-aust

Grumpy Old Man
Staff member
Verified Defense Pro
The operator may well have an "idea" that there is something out there, but isn't likely to have a firm fix on the exact location in 3D space at any specific point in time. If you don't have that, there is nothing that can be specifically targeted, hence you can't direct a weapon against it.

which is the inherent problem with OTHR and bistatic radar.

Works against surface targets, problematic for air. Hence why the tech developments are about companion disparate systems forming up a track to kill dataset

"seeing" a LO/VLO asset means diddly.

the classic example of how people don't understand track management with VLO/LO was a Farnborough air show a few years back where all the kids got excited about a Rapier 2 tracking an F-117 on short finals
 
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SpudmanWP

The Bunker Group
Your original question says it all, ie "How effective".

To be effective, the radar would have to see and track an object early enough to stop it from completing it's mission.

In the instance of the E-2C/D, they are likely trying to prevent a AShM run against the CBG. Against a 4th gen asset you may see & track he him at 400nm which should give you plenty of time to vector an intercept before he launches his AShMs.

The problem with a LO inbound is that that see & track range will be cut down considerably which may allow him to get within firing range before you can vector an intercept. Another problem is that not only is the inbound fighter LO, but the AShM is likely also LO.

Then there is the issue of being the target of the above attack. Since you saw the 4th gen asset at 400+nm and vectored an intercept, he could never get into range to take you out. The same does not hold true for LO. Since he is coming straight for you, he is presenting the worst-case scenario for you, ie his RCS is at it's lowest when pointed directly at the transmitting radar (that would be you). Since you represent the juiciest and slowest of targets, an inbound AAM can use it's most energy conservative, longest ranged flight profile and might very well take you out before you even get a chance to see & track him.

Gee, if we only had a way to defend against inbound AAMs.. (I see another use for CUDA :) )
 

Burke095

New Member
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Well, I found something in an article about the E-2D that seems pretty significant.

"Why is this a major advance? It turns out that continuous scanning across the full 360 degrees limits power applied in any one direction. To keep the scan revisit rate relevant, the radar can only spend a brief instant on each degree of arc before sweeping around again. That is usually more than enough to pick up a target and establish its track. But what if the target is especially hard to see – i.e., stealthy? Or what if it is flying low in ground clutter? In that case, what’s needed is a focused beam that dwells longer, sending more energy in a specific direction. Increased energy transmitted out produces more energy received back and a sharper radar return.
The E-2D for the first time combines both modes in a naval platform. Electronic scanning enables the radar to function both as a rotating beam generating 360-degree coverage, and as a staring beam that can pour radar energy into tracking even the smallest, stealthiest targets. As a result, the E-2D radar is so flexible that its crew can rapidly switch between three main modes of operation. First is the classic rotating beam, ensuring the strike group has no blind spot. Second is a mode which continues the rotation but carves out a 45-degree slice, for example, where power is enhanced. The crew can focus the beam at the direction of a known or cued threat and boost the power while the beam is pointing that direction. It’s the equivalent of scanning the horizon but pausing briefly to stare especially hard at the area of interest. Finally, the E-2D can temporarily turn off the rotating function and funnel all its considerable radar energy at a target."

It seems as if the E-2D will have the ability to focus its entire energy on one single target, allowing it to establish a more solid radar track. It seems to me (although I could certainly be wrong) that this would allow the E-2D to detect the low-observable target in normal operation, then focus on it to actually be able to get a stronger return, track the target, and use CEC to engage the target with, say, an SM-6. Obviously, I don't claim to be an expert (which is why I'm asking you guys), but that seems plausible to me.

Also, I would definitely agree with all the people who have posted that no radar system is perfect or capable of everything -- I certainly don't want to seem like I'm making that claim, or being a E-2D fanboy.

Finally, thanks for all the answers! I'm glad to get the feedback.
 

AegisFC

Super Moderator
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Verified Defense Pro
The CEC and SM-6 combination are not really openly talked about even though you can find unclass information on both. Thus it they are possibly the most under-hyped weapons the USN has in the near future (SM-6 isn't currently fielded).
 

mAIOR

New Member
The CEC and SM-6 combination are not really openly talked about even though you can find unclass information on both. Thus it they are possibly the most under-hyped weapons the USN has in the near future (SM-6 isn't currently fielded).

Didn't even knew CEC existed till now... Just did a quick google on it and what amazing little system. It's a bit like what is used in astronomy and physical Geodesy. Basically, you'll have data integration equivalent (more or less) to an Antenna the size of your most separate assets. Very clever. Though the maths for the static version are complicated enough. I dread to think what USN nerds are going through to solve all the problems arising from merging lots of different sensors from variable speed platforms some of which are going really fast compared to others. If they pull it off, my hat's off to them.

And low cost to boot. Yeah, you don't really need new equipment. Smart investment there.
 

jack412

Active Member

koxinga

Well-Known Member
there is no "video" in track management

track data is like a high fidelity CSV file

unless you can sustain 3 dimensional tracking across complex conditions, then all you have is a 2 dimensional plot - plotting is insufficient
Yes, that's what I meant (see my first sentence video->plots->tracks). Maybe the second para didn't come across clearly when I skipped directly into track management.

I agree, how much a vague, inconsistent echo of a LO/VLO target would be useful?
 

gf0012-aust

Grumpy Old Man
Staff member
Verified Defense Pro
Yes, that's what I meant (see my first sentence video->plots->tracks). Maybe the second para didn't come across clearly when I skipped directly into track management.
yep, its the frailty of internet debate, easy to lose traction on the subject issue

I agree, how much a vague, inconsistent echo of a LO/VLO target would be useful?
not much, data needs to be cross validated and verified across multiple sources before it will be regarded as actionable or safe for use in other actions

echos can be spoofs etc....

one of the advantages of LO/VLO is that they take advantage of the broader ewarfare/sigwarefare/comms engine of companion systems and can dictate to red team what they want you to see as well as what you can't see.

LO/VLO platforms in their own right have a greater opportunity to dictate the fight and engagement terms in their own right - and this is in isolation of companion systems and platforms which they can bring in to enhance the information set
 

Burke095

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yep, its the frailty of internet debate, easy to lose traction on the subject issue



not much, data needs to be cross validated and verified across multiple sources before it will be regarded as actionable or safe for use in other actions

echos can be spoofs etc....

one of the advantages of LO/VLO is that they take advantage of the broader ewarfare/sigwarefare/comms engine of companion systems and can dictate to red team what they want you to see as well as what you can't see.

LO/VLO platforms in their own right have a greater opportunity to dictate the fight and engagement terms in their own right - and this is in isolation of companion systems and platforms which they can bring in to enhance the information set
So, since it is established that low-observable targets produce a weak/inconsistant image, but are nevertheless detectable, how would the fact that the E-2D can focus all of its energy into a pencil beam to project on one single target affect its ability to produce a stronger track? It would seem to me that the ability to do that would be capable of turning a weak return into a strong enough track to direct a weapons system -- as long as the LO target was at least detected, concentration of radar energy could be used to sharpen the "image" that was created.

It also seems as if the ability to detect LO targets would be enhanced by the fact that the J-20 and PAK FA aren't reported to be exceptionally "stealthy." Apparently, Bill Sweetman stated that, due to its use of canards, the J-20 would be highly unlikely to have a frontal RCS of less than 0.01 m2 (and one estimate put the RCS at as high as 0.1 m2), and the PAK FA has been estimated to be between 0.01 m2 and 0.5 m2 (putting it a bit more detectable than the F/A-18E/F, if the higher estimate is the correct one). Obviously, we don't know the exact RCS, and those figures are estimations, but it would appear as if the J-20 and PAK FA aren't VLO (defined as less than 0.001 m2, or -30 dB), just LO.
 

Feanor

Super Moderator
Staff member
It also seems as if the ability to detect LO targets would be enhanced by the fact that the J-20 and PAK FA aren't reported to be exceptionally "stealthy." Apparently, Bill Sweetman stated that, due to its use of canards, the J-20 would be highly unlikely to have a frontal RCS of less than 0.01 m2 (and one estimate put the RCS at as high as 0.1 m2), and the PAK FA has been estimated to be between 0.01 m2 and 0.5 m2 (putting it a bit more detectable than the F/A-18E/F, if the higher estimate is the correct one). Obviously, we don't know the exact RCS, and those figures are estimations, but it would appear as if the J-20 and PAK FA aren't VLO (defined as less than 0.001 m2, or -30 dB), just LO.
This would heavily depend on context. If they have stand-off EW support, and can sufficiently degrade the defenders IADS, they may be able to achieve penetration despite their lack of "true" VLO. Keep in mind the PAK-FA is designed according to the technical requirement of the Russian Air Force. Their biggest threats are weak conventional militaries, and insurgents. Even dealing with the Georgian Buk-M1 systems was no problem for the onboard EW of an Su-34 prototype.

I understand that we're considering this in the context of a third world customer, but then third world customers are a very long way from being able to purchase the PAK-FA. Depending on the Russian defense budget, PAK-FA might be limited to Russian and Indian orders past 2025. So realistically the question is, within what context would the ability of the E-2 to detect the T-50 even be relevant...
 

gf0012-aust

Grumpy Old Man
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Verified Defense Pro
So, since it is established that low-observable targets produce a weak/inconsistant image, but are nevertheless detectable, how would the fact that the E-2D can focus all of its energy into a pencil beam to project on one single target affect its ability to produce a stronger track? It would seem to me that the ability to do that would be capable of turning a weak return into a strong enough track to direct a weapons system -- as long as the LO target was at least detected, concentration of radar energy could be used to sharpen the "image" that was created.
the issue is not about an AWACs focusing "all available tracking energy" onto a single target, and considering the processing and sensor power on an E2D, that would be a spectacular and ignorant misuse of a system

track management is more than just seeing a track object light up - even momentarily and then expending energy on confirming whether its real. you just don't see an object on screen and then "magnify" it


It also seems as if the ability to detect LO targets would be enhanced by the fact that the J-20 and PAK FA aren't reported to be exceptionally "stealthy." Apparently, Bill Sweetman stated that, due to its use of canards, the J-20 would be highly unlikely to have a frontal RCS of less than 0.01 m2 (and one estimate put the RCS at as high as 0.1 m2), and the PAK FA has been estimated to be between 0.01 m2 and 0.5 m2 (putting it a bit more detectable than the F/A-18E/F, if the higher estimate is the correct one). Obviously, we don't know the exact RCS, and those figures are estimations, but it would appear as if the J-20 and PAK FA aren't VLO (defined as less than 0.001 m2, or -30 dB), just LO.
I'd have a low level of confidence on any publicly stated RCS figures. I've seen publicly claimed figures for various platforms which are way off base on the classified data

unless someone has done full battery pole tests as well as used some empirical data from the manufacturer/builder, then its a finger pluck. Some of the finger pluck claims touted to be based on some magical program developed on home computers needs to be taken with a tonne of salt thrown over the shoulder.

You certainly wouldn't want to plan missions around them....

detection credibility and confidence has to be measured against the red team capability.
 

AegisFC

Super Moderator
Staff member
Verified Defense Pro
So, since it is established that low-observable targets produce a weak/inconsistant image, but are nevertheless detectable, how would the fact that the E-2D can focus all of its energy into a pencil beam to project on one single target affect its ability to produce a stronger track? It would seem to me that the ability to do that would be capable of turning a weak return into a strong enough track to direct a weapons system -- as long as the LO target was at least detected, concentration of radar energy could be used to sharpen the "image" that was created.
That "pencil thin beam" might be for a different purpose. :cool:
 

ADMk2

Just a bloke
Staff member
Verified Defense Pro
the classic example of how people don't understand track management with VLO/LO was a Farnborough air show a few years back where all the kids got excited about a Rapier 2 tracking an F-117 on short finals
Of course I'm sure the fankiddies completely disregarded the Luneberg lens routinely carried in public spaces by VLO/LO aircraft and what contribution they made to such events...

:rolleyes:

Whatever could these (inflight ejectable) type devices be?
 
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