F-22 / F-35 5th Generation jets | News & Discussions.

[moon_light]

@gambit : what do you think about this assessment here :

A common misconception is that any low-frequency radar can render stealth useless regardless of their transmitting power or aperture size (Ex: Tikhomirov NIIP L-band transmitter on the leading edge of Flanker series are often cited by enthusiasts as a counter stealth system ) , that is wrong however , while it true that stealth aircrafts will have higher RCS in Mie region.It is important to remember that given equal radar aperture area , lower frequency radars will have much lower gain compared to high-frequency radars , thus, they cannot concentrate energy as much and more vulnerable to jamming , lower gain also give them lower accuracy. As a result, most low-frequency radars have much bigger transmitting antenna compared high-mid frequency radar ,it is also the reason that fighters fire control radar still work in X-band, because a L-band , VHF band radars of similar size would be too inaccurate for any purpose others than early warning (their accuracy can be estimated by radar gain equation ).Simulation done by MBDA also shown that despite operating within low-frequency range from UHF to F band , AWACs radar still struggle to detect stealth aircrafts from their frontal aspect.

Another common misconception is that the lower the operating frequency of the radar ( longer wavelength ) , the better it would perform again stealth assets , that is wrong, however , as can be seen from table above , even within Mie region , target’s RCS fluctuate significantly and can be smaller than value measured in optical region depending on exact frequency and target size. It is also important to note that if radar wavelength is too long compared to target dimension , it can fall into Rayleigh region , in which target’s RCS can get much smaller than in optical region

https://basicsaboutaerodynamicsandavionics.wordpress.com/2016/04/12/radar-electronic-countermeasure/
And this photo

https://basicsaboutaerodynamicsandavionics.wordpress.com/2016/03/29/electronic-countermeasure-ecm/

 

[randomradio]

@gambit : what do you think about this assessment here :

A common misconception is that any low-frequency radar can render stealth useless regardless of their transmitting power or aperture size (Ex: Tikhomirov NIIP L-band transmitter on the leading edge of Flanker series are often cited by enthusiasts as a counter stealth system ) , that is wrong however , while it true that stealth aircrafts will have higher RCS in Mie region.It is important to remember that given equal radar aperture area , lower frequency radars will have much lower gain compared to high-frequency radars , thus, they cannot concentrate energy as much and more vulnerable to jamming , lower gain also give them lower accuracy. As a result, most low-frequency radars have much bigger transmitting antenna compared high-mid frequency radar ,it is also the reason that fighters fire control radar still work in X-band, because a L-band , VHF band radars of similar size would be too inaccurate for any purpose others than early warning (their accuracy can be estimated by radar gain equation ).Simulation done by MBDA also shown that despite operating within low-frequency range from UHF to F band , AWACs radar still struggle to detect stealth aircrafts from their frontal aspect.

Another common misconception is that the lower the operating frequency of the radar ( longer wavelength ) , the better it would perform again stealth assets , that is wrong, however , as can be seen from table above , even within Mie region , target’s RCS fluctuate significantly and can be smaller than value measured in optical region depending on exact frequency and target size. It is also important to note that if radar wavelength is too long compared to target dimension , it can fall into Rayleigh region , in which target’s RCS can get much smaller than in optical region

Yes, this is true... for now.

In about 5 years, this entire thing's going to be irrelevant. A lot of radars today are still being built for one particular part of the spectrum. In about 3-5 years a new radar will be available which will work in multiple sections of the spectrum. So shaping an aircraft only for a small part of the spectrum is irrelevant, at least in the mid to long term.

I'll keep it simple. Everybody can see the F-22/F-35 with their eyes right? That means it is not stealthy at all in the visible spectrum. So if you want to counter the F-22/F-35 type stealth, make a radar that works in the visible spectrum. Basically in any part of the spectrum you know that the F-22/F-35 stealth won't work.

A lot of people will critic such technology and say blah, blah attenuation, blah, blah, processing etc. But even that's becoming irrelevant if you use the right parts of the spectrum with specifically designed Tx/Rx systems.

Then there's passive radars. Passive radars are already becoming big, and already operational in a few jets. They are able to absorb multiple sources of emissions and accurately get 3D information of the target without emissions of their own. Right now they are range limited in some aspects, but can generate very high quality tracking information in some aspects.

 

[moon_light]

A lot of radars today are still being built for one particular part of the spectrum. In about 3-5 years a new radar will be available which will work in multiple sections of the spectrum. So shaping an aircraft only for a small part of the spectrum is irrelevant, at least in the mid to long term.

The link i just posted literally talk about the misconception about stealth and frequency

I'll keep it simple. Everybody can see the F-22/F-35 with their eyes right? That means it is not stealthy at all in the visible spectrum. So if you want to counter the F-22/F-35 type stealth, make a radar that works in the visible spectrum.

So you mean we should a very bright torch basically ?

But even that's becoming irrelevant if you use the right parts of the spectrum with specifically designed Tx/Rx systems.

Personally , i dont think you can just bypass physical barrier by saying blah blah technology , each part of spectrum have their own pros and cons

Then there's passive radars. Passive radars are already becoming big, and already operational in a few jets. They are able to absorb multiple sources of emissions and accurately get 3D information of the target without emissions of their own. Right now they are range limited in some aspects, but can generate very high-quality tracking information in some aspects.

Dont you mean RWR ?, as far as i understand the so called passive radar are just very modern RWR , they still have trouble in measuring range for firing solution
https://basicsaboutaerodynamicsandavionics.wordpress.com/2016/03/02/rwresm-and-passive-geolocation/

 

[randomradio]

The link i just posted literally talk about the misconception about stealth and frequency

No, it was talking about how using lower frequencies isn't particularly useful in detecting stealth aircraft.

So you mean we should a very bright torch basically ?

Anything that emits is a 'bright torch', whether it is in the visible spectrum or not. Humans being able to see only in the visible spectrum is a damper of sorts. So I gave that as an example because it's easier to understand.

Personally , i dont think you can just bypass physical barrier by saying blah blah technology , each part of spectrum have their own pros and cons

Of course they do. But a lot of those cons are becoming less of a hurdle.

Dont you mean RWR ?, as far as i understand the so called passive radar are just very modern RWR , they still have trouble in measuring range for firing solution

RWR is too simple. There are a whole bunch of new technologies added into a passive radar capability. RWR by itself cannot provide targeting information in 3D.

But passive radars are now accurate enough to provide firing solution. For example, current jets do not have the capability to create a radar bubble yet. But they are capable of creating a bubble against enemy emissions. So with enough investment, you can have a jet engage, say, a missile that's come into your bubble. Now this bubble could only have a radius less than 25Km, but that's within the range where the active seeker works. You can now use whatever self-defence equipment you possess to deal with that threat.

The same for an aircraft that's come too close.

 

[gambit]

@gambit : what do you think about this assessment here :

A long time ago on this I challenged the argument that low freq is 'anti-stealth'.

First, I did not challenge the TECHNICAL validity that low freq, or long wavelength, can better illuminate a 'stealth' aircraft.

Second, what I challenged was the TACTICAL advantages of that argument. So far, none such tactical advantages materialized.

Those who posted the argument that low freq is 'anti-stealth' always run away from the tactical rebuttal that such signals would reveals the seeker to the 'stealth' attacker long before the seeker would find the 'stealth' attacker. So who have the real tactical advantage here ? Not the low freq station.

Finally, there is no such thing as a 'passive' radar. Who wants to take that on ? The PDF Chinese and their suck-ups certainly do not.

 

[randomradio]

Finally, there is no such thing as a 'passive' radar. Who wants to take that on ? The PDF Chinese and their suck-ups certainly do not.

You mean to say something that was first coined in the 1930s and is operationally available and sold by many companies under that moniker suddenly doesn't exist?

And I am a Chinese suck-up? Why? Because I said you are trying too hard to get into useless arguments about the J-20 and Mig 1.44 with people who don't matter, thereby cluttering the forum with useless posts, which frankly is a waste of time and bandwidth, even though I agreed with you?

 

[moon_light]

No, it was talking about how using lower frequencies isn't particularly useful in detecting stealth aircraft.

But if you go up , unless you go up to visible light or infrared spectrum , then it will be harder to detect stealth aircraft

Anything that emits is a 'bright torch', whether it is in the visible spectrum or not. Humans being able to see only in the visible spectrum is a damper of sorts. So I gave that as an example because it's easier to understand.

Yes but there is attenuation problem with high frequency

RWR is too simple. There are a whole bunch of new technologies added into a passive radar capability. RWR by itself cannot provide targeting information in 3D.

modern RWR like ASQ-213 , ALR-99, ASQ-239 can , the techniques they used are explained in the link too

But passive radars are now accurate enough to provide firing solution. For example, current jets do not have the capability to create a radar bubble yet. But they are capable of creating a bubble against enemy emissions. So with enough investment, you can have a jet engage, say, a missile that's come into your bubble. Now this bubble could only have a radius less than 25Km, but that's within the range where the active seeker works. You can now use whatever self-defence equipment you possess to deal with that threat.
The same for an aircraft that's come too close.

It can only do that at short range because it cannot determine range , as i understand
still something like DAS would be more useful in that case in my opinion.

 

[randomradio]

But if you go up , unless you go up to visible light or infrared spectrum , then it will be harder to detect stealth aircraft

It isn't necessary to go that high up.

modern RWR like ASQ-213 , ALR-99, ASQ-239 can , the techniques they used are explained in the link too

RWR simply warns you about a radar threat. The systems you named are not RWRs. They are now simply called Electronic Support Systems or Countermeasures system or something like that. And RWR is just one small part of this system. For example, when we talk about the ASQ-239, it has a lot of components in it, including IR. Basically, it's all unified now.

It can only do that at short range because it cannot determine range ,

Is more than 200Km at 0.1deg angular accuracy good enough?

How do you think astronomers calculate distances of stars and other cosmic bodies? It's all in the math.

Anyway, this has nothing to do with passive radars. It uses known location and frequencies of existing transmitters and then uses that data to generate a radar picture in 3D. That transmitter has nothing to do with the passive radar.

They are multistatic radar systems which accept any signal to create a radar picture. And the passive radar is restricted by the capabilities of the transmitter itself, since the transmitter is not in anyway related to the radar's receiver, unlike active radars which carry inbuilt receivers. But better the transmitter, the better is the capability of the radar. So the difference varies depending on whether you are using SAM radars or cellphone signals.

 

[moon_light]

It isn't necessary to go that high up.

If you dont go that high up then how is it gonna be effective again stealth aircraft ?

RWR simply warns you about a radar threat. The systems you named are not RWRs. They are now simply called Electronic Support Systems or Countermeasures system or something like that. And RWR is just one small part of this system. .

Call them what you want , technically speaking they are just very advanced RWR. And also RWR doesnt just warn you about threat , RWR like APR-38/47 on F-4G can geolocate ground threat location too

For example, when we talk about the ASQ-239, it has a lot of components in it, including IR. Basically, it's all unified now..

If i remember correctly the IR one is DAS , ASQ-239 is strictly ECM and RWR

Is more than 200Km at 0.1deg angular accuracy good enough?

dude , did you just quoted Picard ?
Also it not that hard to get good angular accuracy again stationary ground targets many systems do that because altitude different are known so triangulate is simple. It is accuracy again aircraft that is the problem.

How do you think astronomers calculate distances of stars and other cosmic bodies? It's all in the math.

No , it not just all in the math
here are the techniques that they used to estimate distance to distance stars
http://starchild.gsfc.nasa.gov/docs/StarChild/questions/parallax.html
http://starchild.gsfc.nasa.gov/docs/StarChild/questions/cepheids.html
http://starchild.gsfc.nasa.gov/docs/StarChild/questions/supernovae.html
http://starchild.gsfc.nasa.gov/docs/StarChild/questions/redshift.html
apart from triangulation , none are applicable to aircraft

Anyway, this has nothing to do with passive radars. It uses known location and frequencies of existing transmitters and then uses that data to generate a radar picture in 3D. That transmitter has nothing to do with the passive radar.
They are multistatic radar systems which accept any signal to create a radar picture. And the passive radar is restricted by the capabilities of the transmitter itself, since the transmitter is not in anyway related to the radar's receiver, unlike active radars which carry inbuilt receivers. But better the transmitter, the better is the capability of the radar. So the difference varies depending on whether you are using SAM radars or cellphone signals.

So basically what you want to talk about are multi static radar ? they will still need a transmitter , and once the transmitters is off they would still be useless. Not quite the same as the myth that they can do everything in complete silent.

 

[gambit]

You mean to say something that was first coined in the 1930s and is operationally available and sold by many companies under that moniker suddenly doesn't exist?

Yes. There is no such thing as a 'passive' radar. I do not care what these companies sales brochures says. Neither do established masters of the field, one of whom is Merrill Skolnik, believes so. They say no such thing as 'passive' radar, they taught it, and I learned it. And I agree with them.

I'll keep it simple. Everybody can see the F-22/F-35 with their eyes right? That means it is not stealthy at all in the visible spectrum. So if you want to counter the F-22/F-35 type stealth, make a radar that works in the visible spectrum. Basically in any part of the spectrum you know that the F-22/F-35 stealth won't work.

OMG...!!!

You are being grossly simplistic.

FYI...What you are talking about ALREADY exists. It is called the SEARCH LIGHT. Essentially, you cast a beam of visible wavelengths, they bounced off a body, and you see that body.

 

[randomradio]

If you dont go that high up then how is it gonna be effective again stealth aircraft ?

You can do that with mm waves itself. Why go into nm?

Call them what you want , technically speaking they are just very advanced RWR. And also RWR doesnt just warn you about threat , RWR like APR-38/47 on F-4G can geolocate ground threat location too

RWR + direction finder + range finder etc are all part of ESM. And all of this is unified.

If i remember correctly the IR one is DAS , ASQ-239 is strictly ECM and RWR

The ASQ-239 can use data generated from the DAS.

dude , did you just quoted Picard ?

Picard and I have too many differences. He simply doesn't believe in radars.

Also it not that hard to get good angular accuracy again stationary ground targets many systems do that because altitude different are known so triangulate is simple. It is accuracy again aircraft that is the problem.

No , it not just all in the math
here are the techniques that they used to estimate distance to distance stars
http://starchild.gsfc.nasa.gov/docs/StarChild/questions/parallax.html
http://starchild.gsfc.nasa.gov/docs/StarChild/questions/cepheids.html
http://starchild.gsfc.nasa.gov/docs/StarChild/questions/supernovae.html
http://starchild.gsfc.nasa.gov/docs/StarChild/questions/redshift.html
apart from triangulation , none are applicable to aircraft

Math. Geometry is also part of math.

So basically what you want to talk about are multi static radar ? they will still need a transmitter , and once the transmitters is off they would still be useless. Not quite the same as the myth that they can do everything in complete silent.

If any transmitter is off, the radar it is connected to is useless.

 

[moon_light]

You can do that with mm waves itself. Why go into nm?

What make you think MMW is more effective again stealth aircraft than X-band ?

A long time ago on this I challenged the argument that low freq is 'anti-stealth'.

First, I did not challenge the TECHNICAL validity that low freq, or long wavelength, can better illuminate a 'stealth' aircraft.

Gambit as an expert , what do you think about these graphs ? :

 

[randomradio]

Yes. There is no such thing as a 'passive' radar. I do not care what these companies sales brochures says. Neither do established masters of the field, one of whom is Merrill Skolnik, believes so. They say no such thing as 'passive' radar, they taught it, and I learned it. And I agree with them.

Potayto, potahto. As long as you agree about the way it works, you can call it whatever you want. There are disagreements about what a system is called everywhere. Like the French don't believe in the marketing claims of the F-35's marketing team for what constitutes a 5th generation.

A passive radar does not have a transmitter. It merely uses other transmitters to generate track. There can be 2 or 3 or 200 or 400 or 1000 transmitters spread out over a large area.

Just because you don't use the term doesn't mean others don't.

This one in Colorado.
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6979455&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6979455

This one in Kiev.
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6053651&url=http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6053651

Why don't you send a mail out to Merrill Skolnik? Maybe he's more up-to-date about the terms used.

OMG...!!!

You are being grossly simplistic.

Actually I'm not. It's next generation in radar technology. One step ahead of the AESA. An ultra-wideband radar.

Anyway, you missed the point of what I said. I said-

Basically in any part of the spectrum you know that the F-22/F-35 stealth won't work.

I gave the visible spectrum as an example so he could understand what I was talking about. The F-22 is not stealthy in the visible spectrum, so you can see the F-22 in many other parts of the spectrum and not just the X band, say at 100GHz.

FYI...What you are talking about ALREADY exists. It is called the SEARCH LIGHT. Essentially, you cast a beam of visible wavelengths, they bounced off a body, and you see that body.

Yes, a searchlight, but a searchlight that doesn't work in the visible spectrum. This 'searchlight' that's coming up can do facial recognition from 400Km away and can even check what's inside the weapons bay of aircraft. It can even count the number of people inside an aircraft. Think of a TV camera instead, but with X ray vision, that's a much better example. It will have a resolution that's 20+ times higher than current AESA radars. But this will work in far lower frequencies, not the visible spectrum, maybe at least not yet.

 

[moon_light]

Math. Geometry is also part of math.
.

If you read them then you will see that apart from the first one ( which is basically triangulation) the rest are not applicable for the aircraft vs aircraft situation

If any transmitter is off, the radar it is connected to is useless..

What is mean is that the name " passive radar " creating the illusion that the radar can operate silently , in fact it still need a transmitter and still obey the rule of normal radar

 

[randomradio]

What make you think MMW is more effective again stealth aircraft than X-band ?

The F-22/35 were not made for VLO in the mmw bands. It does work a bit in the mmw, but not as much as cm bands. Radars in the mmw bands are coming up, with very high resolutions.

You will eventually see the combining of LIDARs and RF radars within just a few years.