I can only report what people involved in developing future weapons and tactics tell me. You are free to choose not to believe what they say. But I will place more credence in persons actively involved in this field.

I’m not disbelieving anyone, just pointing out facts.

This is a common belief in enthusiast circles, and I have even seen it cited by some defence academics, but can you point me to a published statement or technical paper by a radar manufacturer that confirms it? (I am always happy to be proved wrong. That is how one learns.)

If it’s a commonly acknowledged fact often stated by defence academics, I think the burden of proof rests on you to disprove it.

http://www.satellite-evolution.com/issues-2011/gmc-oct-2011/radar.pdf

This means that the radar is able to track more targets
at any one time as the AESA can switch frequencies and produce
beams in a variety of different frequencies simultaneously,
giving excellent situational awareness. The AESA can
produce strong signals whilst still remaining stealthy.

‘Simultaneously’ clearly implies at the same time. Signal processing is then used to detect the response. I can tell you that the amplitude of the different frequencies can also be varied during pulses which leads to a characteristic pattern on the response, which is easily extracted from the noise on return by signal processing. It should be remembered that radar SP is as good as jammer SP and it has the advantage of knowing what it’s looking for.

The Journal of Electronic Defense is a trade journal published by the professional organisation of the US EW industry, which runs US and international EW conferences classified at up to ‘Secret – US only’ level. I would hesitate to regard anything they publish as “dubious”.

I have checked through my back copies, and the article in question was published last December. Had the statement been wrong, I would have expected some reaction from the readership. Do you remember the brouhaha several years ago when Theodore Postol of MIT published what turned out to be incorrect and over-optimistic estimates of the performance of an Iranian ballistic missile? Several persons with extensive expertise in missile modelling were quick to criticise his data, and point out weaknesses in his reasoning.

Dubious can simply mean ‘misleading’. You still haven’t mentioned the radar it was working against. The problem with your reasoning is that you are expecting equal computing technology to be as good a radar back end at detecting its own signal without knowing what it is. That’s like putting a needle in a haystack and someone else claiming to be able to find where it is as fast as you with only the same observational powers.

I cannot speak for lidar, but a leading seeker designer has stated that using MM wave rather than centimetric wavelengths is of no help when trying to engage a stealth aircraft.

Depends on power. Obviously MWR is range limited due to atmopsheric absorption at the current levels hence why it’s no help yet but I’m willing to be that RAM is nowhere near as effective against it. Because stealth aircraft are visible to the human eye, we can deduce that higher frequencies are less well absorbed.

difference between SARH & ARH is irrelevant in terms of range,
except autonomous missile have an advantage at close range when the shooter might have problem keeping the nose pointed at target
but would be interesting to compare survivability of the shooter of respective missile

It’s actually completely relevant in terms of both the accuracy of the homing and the time the enemy gets to develop jamming and it’s even possible they may end up having to jam the aircraft and missile radar at the same time. Upon introduction of the AMRAAM, Pk almost doubled over that achieved by AIM-7M is Desert Storm, even though the shots were taken from a lot further away on average. The enemy was of the same calibre or better (East European) than that in Desert Storm, so there are no arguments to be had there.

The future shape of air-to-air combat in a world where both sides are stealthy is a fascinating subject, but one that I have explored professionally to only a limited degree. As you might imagine, those directly involved in next-generation weapons and tactics can be remarkably laconic when dealing with an outsider. But the general idea (at least in some quarters) will still be to engage the enemy at BVR, and at least one of next generation of BVRAAM missiles will be designed with such combat in mind.

Theoretically the current ones can if you pick the target up on IRST but at those kinds of ranges BVR separation is unlikely to be maintainable and a merge is likely.

At any moment in time, all the elements in an AESA array are dedicated to a single beam-forming task, and operate at the same frequency. The result is a beam of RF energy that may have better characteristics than those from a traditional antenna, but it is still a single beam of relatively high power. The frequency of that beam may be changing from pulse to pulse, but each of these individual pulses in created by an array of elements all emitting the same frequency but with the phase delays needed to create the required beam shape and direction.

This is not the case. The main advantage of AESA over PESA is the ability of separate T/R modules to operate on different frequencies and combine frequencies in a single beam. Each T/R module itself usually doesn’t change in the middle of a pulse but theoretically there isn’t anything preventing such an occurrence and there are developments at large.

As I have already explained, the pulse that the jammer manipulates and retransmits is the pulse that was sent by the radar. So whatever electronic coding or fingerprinting the original pulse contains will also be present in the version transmitted by the jammer. The radar is waiting to receive an incoming pulse whose characteristics match those of the transmitted pulse, and the jammer is happy to oblige in order to seduce the enemy radar into accepting the false signal.

This is done on a pulse-to-pulse basis, so if the next pulse sent by the hostile radar has a different fingerprint, that will be present when that next pulse is retransmitted.

But you’re only duplicating it after the fact and there’s nothing to say the pulse will continue as it started.

I am not familiar with how such fast set-on speeds are achieved in practice, but nanoseconds seem to be the unit of time necessary. A recent article on DRFM in the Journal of Electronic Defense talked of a radar pulse being detected and the jamming activated in a total time of 100 nanoseconds in order to cover 90% of the pulse duration. The 10% period for which the pulse was not jammed would have a minimal effect on the effectiveness of the jamming, the author stated.

Dubious. Operating a 4GHz, you’d be hard pushed to perform a program of any complexity in 400 clock cycles. If it’s against a simple non-AESA radar, then that’s a different matter. What radar was it against?

Exactly – the Red Teams I mentioned earlier were specifically tasked with trying to devise an anti-stealth kill chain. A broken kill chain means no reliable prospect of a kill.

Laymen love to cite the downing of the F-117 as ‘evidence’ than low-observable technology no longer works, ignoring the fact that the aircraft was not radar-invisible, and such a quality has never been claimed for it. They ignore the fact that the F-117 completed more than 2,100 combat sorties with the loss of only a single aircraft. All that the Serbian kill demonstrated is what we have always known – get close enough to a radar-guided SAM site and you will be engageable.

Another one was also damaged. What it could also be seen to demonstrate is that RF is part of a wider EM spectrum and RAM clearly doesn’t work against the whole spectrum, hence it’s unlikely to work equally against the whole RF band either. At extremely high frequencies it will also fall down. MWR and IR Lidar could be a problem for it.

At this point it might be worth asking yourself –

“Why did the Russians design PAK-FA to be so maneuverable when conventional logic would suggest they focus more on VLO instead?”

Two stealth aircraft walk into a bar…..

If you have 2 stealth aircraft against one another, obviously stealth works both ways. If you have a significant number up against each other then inevitably it will probably end WVR even if there are a few BVR shots. Who said BVR didn’t require manoeuvrability anyway?

I never suggested it was easy, just that it was doable.

Is it? Obviously radar makers and ECM people will do their best but since the introduction of AESA, the advantage is definitely with the radar people. If effective jamming was possible and detection easy, stealth would be redundant for air superiority purposes because every fight would end up WVR.

Cannot comment on the alleged hop rate of the APG-77, but irrespective of pulse length, each pulse is being transmitted at whatever power level the radar requires, so it is going to be strong, on the same bearing as the last one, and within a predictable frequency range.

I have no doubt that integrating across the X-Band wrt time will probably detect AESA but that on its own is a significant task. Actually jamming in such a way that pulses are jammed upstream is the hard part. The strength won’t be as easily detected as you think, because the power can be split over a pattern across the frequency range, so whilst it adds up to a lot, the individual intensity at any frequency is low and easily mistaken for noise unless you continually add everything together.

I do not know what specifically you mean by ‘coding’ – the word could have several meanings in this context. However, modern digital RF memory (DRFM) can handle whatever form of coding the radar pulses may have received. You do not need to ‘establish’ the coding that the enemy radar applied to the pulse, just get the DRFM to copy and mimic the pulse.

The coding isn’t constant, it’s time varying too and would again require prediction and more advanced ones even implement changes when an attempt at jamming is made or an enemy is detected.

Milliseconds are out of the question – think in terms of nanoseconds for locating the pulse and starting to emit your ‘doctored’ return. That is the speed needed to make sure that you are jamming for most of the duration of the pulse length.

If you had problems in accepting the concept of working in milliseconds, I would imagine that you will find nanoseconds even less credible. But state of the art EW has always been classified, so I doubt there will be much on the internet for you to see as ‘evidence’.

Show me a fighter with a supercomputer on board and I will think nanoseconds. The problem is that at 1GHz, a single clock cycle = 1 nanosecond. One line of code, depending on what language it’s in, can take anything from several clock cycles at assembly code level to dozens of clock cycles at higher language levels. That’s just one line of code in what must be a very complicated program. Presumably some bits can be done in FPGA but the complexity of actually adding across the X-Band and time to detect a signal and then trying to isolate the signal and then implementing jamming is hugely complicated. Jamming has traditionally been upstream and downstream to provide effectiveness, upstream isn’t possible given the nature of AESA, so that limits you to immediate jamming at the very best. All you can really try do with that is cancel the signal, which is an ar5e of a task in itself and depends on the bearing of the emitter, the orientation of your aircraft and probably even crap like the weather, e.g. how much energy will be absorbed on the return path?

The return is also like a fingerprint, even a feint finger print is still a finger print, so unless you get the whole pulse, or pre-empt it, the jamming is likely ineffective.

Did i say the opposite? RWR have the advantage of stronger signals, Rx to “know” what to search already…

I’m talking about the sending Rx knowing what frequency patterns to look for. An enemy RWR doesn’t know this. The problem is that you have to receive the signal to even begin to guess what it is but then it changes, so you’re always faced with a delay. At best you can jam the back end of the pattern over that millisecond which won’t be effective. The sender will still get their pulse back plus some downstream garbage which is easily ignored because it’s downstream. You could try continuously jamming certain frequencies after monitoring usage and making a prediction but this presents the problem of giving you away because, in itself, it can be detected and then the sending radar can just avoid these frequencies and the unpredictable coding won’t be there in the jamming waveform either.

The absolute best bet in jamming an AESA may just be to send back your own random AESA signal, rapidly varying, and hope that there’s enough overlap with the sender’s signal to mess things up.

DAmn was doing my best in english 🙁
What i’m traying to say is that radar pulses aren’t simply “pings”, but short signal with specific polarization etc. These “patterns” are used by radar receiver to identify its own signals way under background noise threashold using correlators. The same way our GPS identifies a 25W signal coming from 20000 Kms. But the number of these “patterns” is limited.

Why would they be limited? As long as the Rx knows the pattern, they are easily detected on their return and so can take on an unlimited number of patterns. For enemy RWRs who don’t know the pattern, not so easy.