German radar vendor says it tracked the F-35 jet in 2018

[hornetfinn]

Maybe at some point low frequency and multistatic radars will reach the point where they "make stealth obsolete", but the reality is that neither F-22 nor F-35 are one trick ponies. Along with EA, decoys, superior SA, VLO is yet another ace up their sleeve, something eurocanards don't have. The next step would be to roll out hard kill self-defence lasers, just to be sure in the year 2060+.
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I doubt stealth will ever be obsolete. Low frequency and multistatic radars can very likely detect and track stealth aircraft in the right circumstances, but they will not solve most problems. Even if they could direct missiles towards enemy aircraft, the hit and kill probability will definitely be far lower than against non-VLO aircraft. Of course those systems are also big, complex and mostly fixed or have limited mobility. This naturally means that they are expensive, easy to target and not very flexible. I see them as useful tools in some applications, but only small part of the overall capabilities. Higher frequency radars will be needed for most applications and will be by far the most numerous systems in the foreseeable future.

I think it's basically like with submarines. Without stealth the submarine is dead very quickly with modern detection and weapon systems. With stealth they are very difficult targets even with modern detection and weapon systems. Alfa class submarines were extremely fast and maneuverable subs, but that was quickly countered with more advanced and faster torpedoes and other weapons to kill them. Later all submarines went for maximum stealth and sensors with decent top speed and maneuverability.

[kimjongnumbaun]

First, the F-35 was operating with its mode c transponder on for air traffic control. Wow, done guy tracked a plane that was actively broadcasting its position for ATC. Please forgive me if I don’t give him a Nobel prize in science.

Two, TV, radio, etc operate in the VHF bandwidth. That’s similar to the bandwidth of low frequency radar. Automatically, we know it can’t get a weapon track on a plane because low frequency radar updates information at a low frequency, and it isn’t fast enough to generate a weapons track.

If anyone has worked with radar then they know that stealth planes operate below the noise floor. If I’m not too lazy so can draw diagrams. But basically, stealth planes are lost in clutter on the radar scope. They don’t generate spikes which makes them near impossible to find even with new fan-dangled radar. Either you attempt to find them in the mass of noise, or you filter out the noise and filter out the stealth plane with it.

The engineers behind the F-22 and F-35 were not stupid. When they said that both planes would have a stealth advantage until 2070, it’s because they understand how radar works and how difficult it is to beat stealth.

[hythelday]

It's also worth noting that every modern radar manufacturer claims their radars have anti-stealth capability, includibg but not limited to SMART, S1850, Hawkeye's APS-145, SPY-6 etc. If you ain't anti-stealth then you ain't in the game these days.

[element1loop]

That's why you tend to see a cadence for passive radar systems:
a. A new waveform becomes popular like DTV or GPS or 3GSM.
b. New passive radar systems that exploit those waveforms get developed and promoted.
c. Someone shows up with a cheap deception jammer
d. The passive radar community goes off hunting for the next "ideal" waveform (goto a)

Prevailing gain matters in receiving reflected energy at significant distance with a useful signal to noise ratio. It's why high wattage broadcasters are the first choice. The lower the gain of the active emitter signal, the easier to squelch it into the noise floor and make it useless. So this still needs a powerful illumination source to get a useful gain for range. Kill the highest gain emitters and you've made it almost useless. Add tactical noise and it's definitely useless.

On top of that the antenna is detecting a tractable moving delayed return. Fine, just sample and emit an infinite number of randomly delayed returns. Sort that out.

[ricnunes]

Two, TV, radio, etc operate in the VHF bandwidth. That’s similar to the bandwidth of low frequency radar. Automatically, we know it can’t get a weapon track on a plane because low frequency radar updates information at a low frequency, and it isn’t fast enough to generate a weapons track.

Absolutely!
And I think that people must start realizing once and for all that stealth aircraft are also stealth (present a low RCS) against VHF bandwidth/radar.
For instance here's a good reading about the 1999 F-117 shot down, which you can download below:
http://www.mediafire.com/file/ckh4c99ry ... 5.pdf/file

In the document above you can read the following:

According to statement of Zoltan Dani he made little adjustments in the operational wavelength of the P-18 without permit from their superior officer. This was not so unique move in peacetime sometimes did operators in WPACT but it was forbidden because it could jam the TV broadcast. The change was minimal the operation frequency was changed only with 6 MHz (normal operational range is about 150 MHz). It is hard to judge how big the impact was the frequency change but the P-18 was able to detect the F-117 from 25 km range with 10 km offset distance.

For those that don't know, the P-18 is a VHF radar:
https://en.wikipedia.org/wiki/P-18_radar

So, a modified VHF radar albeit being old tech was only able to detect an also old tech stealth aircraft - the F-117 - at a range of ONLY 25 km.
So again, this means that Stealth aircraft also present a low RCS against VHF radars/bandwidth.

Granted that a stealth (and non-stealth) aircraft RCS seems to increase somehow against lower bandwidth (such as VHF) compared to higher bands (X band for instance) but the increase doesn't seem to be that big (operationally).
Using the same example/source above, one can also read:

It is also just pure luck that that old Dvina SAM site was in a good place to have the necessary
engagement zone and change for guidance. The tracking range of the SNR-125 fire control radar
(guidance station) was only about 15 km against the F-117. If the F-117 had flew just some km farther
or closer or they turn on the P-18 just a bit later they had no chance for success.

The SNR-125 operates on I/D-band, being the D-band relatively close to X-Band or more precisely belonging to the S-band.

So lets see, a VHF radar detects a stealth F-117 at a maximum range of 25km while a I/D-band tracks the same F-117 at a maximum range of 15km. So, I would say that the diferences are NOT that big at all.

Moreover, I'm sure that the US and LM learned a lot about the F-117 shot down and as such that the F-35 stealth is also optimized against VHF bandwidth.

And to conclude, people have to realize that any technology that may eventually come that would allow for instance detecting a stealth aircraft like the F-35 at lets say a range of 100km (or even more) will inevitably detect a non-stealth aircraft at much, much further/longer distances. This alone means that Stealth will never be obsolete.

[herciv]

The B-2 Spirit was also track by a french radar named NOSTRADAMUS at a very long Range.
Some references here :
https://fr.wikipedia.org/wiki/Northrop_B-2_Spirit. I remember the article in lepoint in reference.

[sferrin]

None of these state if the RCS enhancement devices were present. (The B-2 has them too BTW.)

[herciv]

In the case Of nostradamus you are right because its a monostatic solution (ie emitter and receiver in the same place). But in the case of Hensold its a passive radar (ie a multistatic emitter). Then luneberg lenses have no importance there because they can only reflect the wave where it come from then with multistatic emitter its impossible by construction.

[ricnunes]

But in the case of Hensold its a passive radar (ie a multistatic emitter). Then luneberg lenses have no importance there because they can only reflect the wave where it come from then with multistatic emitter its impossible by construction.

Yes, they have. This is because even a passive radar (like that Hensold) as to rely on radio energy reflected/bounced from the target/aircraft.
And stealth aircraft like the F-35 are designed to reflect/bounce back the least radio energy possible. This is done by clever design together with RAM coating/materials that absorb radio energy instead of reflecting/bouncing it.
What does this mean? It means that a luneberg equipped aircraft will reflect/bounce back much more radio radio energy which in practical terms means longer detection range even for a Passive radar.

Anyway, the diference between a "conventional" or "active" radar and "passive radars" like this Hensold is that the former emits its own radio waves while the later relies on other sources (such as TV transmitters) to emit the radio waves. Other than that, the principle is the same/similar.

[F-16ADF]

Of course the F-35's were tracked. Why? Because once the F-35's departed (they were handed off from the Tower to Departure Control, from Departure eventually to one of the Centers) -- and once at and above FL180 (18,000ft), at least in the United States Class A airspace, you MUST be on an IFR flight plan. Meaning you have a filed flight plan, a mode C or S transponder, and in contact with Air Traffic Control. It doesn't matter anyways here, because once the F-35's departed they were handed off to departure control. And were assigned a squawk code for their transponders (or were given one prior on the ground with their filed IFR plan routes).

Even so, you can easily be tracked just by squawking 1200 (VFR).

That is for US airspace, European airspace is probably far more congested.





edit: If the F-35 is flying at an airshow all LL'd up as the US; you can be certain it would have them on in areas outside of the US like Berlin for obvious security reasons. I took this pic back in 2017 at the KMTC airshow, and you can clearly see them.

[vanshilar]

Anyway, the diference between a "conventional" or "active" radar and "passive radars" like this Hensold is that the former emits its own radio waves while the later relies on other sources (such as TV transmitters) to emit the radio waves. Other than that, the principle is the same/similar.

That doesn't get at Herciv's main point that a Luneburg lens is designed to reflect energy directly back toward the source. Whereas passive radar works by detecting the scattered energy that did *not* go back toward the source, i.e. emitter and receiver are at different locations. So it depends on how much the Luneburg lenses scatter radiation away from the source, at the frequencies they're detecting.

[ricnunes]

Anyway, the diference between a "conventional" or "active" radar and "passive radars" like this Hensold is that the former emits its own radio waves while the later relies on other sources (such as TV transmitters) to emit the radio waves. Other than that, the principle is the same/similar.

That doesn't get at Herciv's main point that a Luneburg lens is designed to reflect energy directly back toward the source. Whereas passive radar works by detecting the scattered energy that did *not* go back toward the source, i.e. emitter and receiver are at different locations. So it depends on how much the Luneburg lenses scatter radiation away from the source, at the frequencies they're detecting.

But it does get to Herciv's main point:
Luneburg lenses will and do scatter more energy. Without Luneburg lenses you'll have energy that either won't reflect on anything since the Luneburg lenses are bulges/lumps that "sticks out" from the stealth aircraft airframe and without them (Luneburg lenses) that energy would otherwise pass besides the aircraft (without reflecting on anything) and/or the energy that would otherwise be reflected by the Luneburg lenses but otherwise without them would end up "hitting" the stealth aircraft's airframe would instead be absorbed by the aircraft's RAM coating (or at least a great deal of such energy would).
Understand now?

[awsome]

On the other hand, intentionally attack civilian infrastructure is war crime.

Not at all - during Operation Desert Fox television and radio transmitters were taken out early:

Yes but then again the US buried Iraqi soldiers alive in their trenches with bulldozers. Just because it was done does not mean it was legal. BTW who transmits TV signals anymore?

[usnvo]

Anyway, the diference between a "conventional" or "active" radar and "passive radars" like this Hensold is that the former emits its own radio waves while the later relies on other sources (such as TV transmitters) to emit the radio waves. Other than that, the principle is the same/similar.

That doesn't get at Herciv's main point that a Luneburg lens is designed to reflect energy directly back toward the source. Whereas passive radar works by detecting the scattered energy that did *not* go back toward the source, i.e. emitter and receiver are at different locations. So it depends on how much the Luneburg lenses scatter radiation away from the source, at the frequencies they're detecting.

But it does get to Herciv's main point:
Luneburg lenses will and do scatter more energy. Without Luneburg lenses you'll have energy that either won't reflect on anything since the Luneburg lenses are bulges/lumps that "sticks out" from the stealth aircraft airframe and without them (Luneburg lenses) that energy would otherwise pass besides the aircraft (without reflecting on anything) and/or the energy that would otherwise be reflected by the Luneburg lenses but otherwise without them would end up "hitting" the stealth aircraft's airframe would instead be absorbed by the aircraft's RAM coating (or at least a great deal of such energy would).
Understand now?

Nope, you are ignoring what happens to EM energy when it hits a stealth fighter and how a Luneberg Lens works. The vast majority of "stealth" comes from shaping, not from absorption. Radar energy is reflected in directions away from the transmission source as opposed to nullified or cancelled out.

So, Luneberg lens are passive, they do not amplify the energy, merely make it more concentrated. Essentially it acts like a corner reflector, reflecting more of the signal back to the radar. The total energy reflected is the same, just more is concentrated back toward the transmitter. If anything, use of a Luneberg Lens will decrease the energy reflected in other directions.

But even that is not important. The system in question uses FM signals in the VHF Radio/TV range, so 54-216MHZ while a Luneberg Lens is designed to work in the 2.7-2.9GHZ range used in air traffic control radars. At the higher frequency, the reflectors amplify the signal but at the lower FM frequencies the amplification is much less (if at all) since it is the entire aircraft that reflects the signal.

However, the article illustrates the difficulty of using a passive radar system, especially one in the FM TV Band. First you need multiple receivers all linked together. Look at the receivers, no way you have any vertical beam forming on those and there is no way they are accurate enough horizontally to track the signals by direction with any fidelity. So they are basically working GPS is reverse to use time delay from the signal at multiple points to track a reflected source. That is really hard to do, especially the detection part, over tactically relevant ranges. The German company clearly indicated that they had to detect and track the F-35s on ADS-B before they could track them with the passive radar. Because sorting out the hundreds of thousands of targets (note that every moving item such as planes, cars, trains,etc also reflects the signal and you can't use Doppler to sort them out for obvious reasons) is hard as well as the fact that any pair of signals could be the target, so the numbers go up exponentially.

And of course, it is almost ridiculously easy to spoof the signal and/or eliminate the transmitter, especially given that things like TV stations and big radios are both prime targets and easily located.

So passive radar is not that big of a deal yet (as opposed to detecting emissions from the aircraft itself, like radio). But the fact that the aircraft had Luneberg lenses, IFF, or ADS-B does not invalidate the test. But it is unlikely any foe would have their receivers near the end of the runway either.

[Corsair1963]

When major powers stop developing and buying 5th and 6th Generation Stealth Fighters and Bombers. Then it's time for concern...



Otherwise, just the usual wild speculation and rumor.....