Russia sells S-400 systems to China


BoraTas

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Finally, the aggressor will always employ electronic attack aircraft together with stealth aircraft. Jamming VHF/UHF radars is typically easier than higher frequency radars. A VHF radar is limited to the range of 30 to 300 MHz (max. bandwidth: 0.27 GHz). That makes it a far easier task to jam than an X-band radar that operates within a 4GHz (8GHz-12GHz) frequency range. Finally, their poor angular resolution makes them susceptible to geometric spoofing techniques.

There's a good chance that a pack of F-35s following a Growler could kill a loner Nebo radar with their SDBs without ever being detected. But in a large defense network of multiple radars and AEW aircraft, a VHF radar is a welcome asset as it further complicates enemy attack plans.

The 40N6 missile is an active-radar homer. Intermediate range (200km and 250km) missiles are SARH and <120km range are ARH.
Are you sure VHF radars are easier to jam? I heard this multiple times but I didn't found any evidence. Proportion wise VHF band is much wider than X-band after all. It is plausible that an antenna optimized for 8 GHz would work well enough at 12 GHz but an antenna optimized for 30 MHz would suck for 300 MHz. As for as I know, antenna selection is all about proportions. Also, most aircraft do not even carry any equipment that would generate or detect VHF waves effectively. As for as I know the F-35 has some little capability for detecting and jamming VHF radars with a set of large antennas at leading edges but beyond that VHF and HF are dealt with dedicated EW systems.

Also, thank you for the correction about 40N6. I probably thought of 200 and 250 km range missiles.
 

nlalyst

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Are you sure VHF radars are easier to jam? I heard this multiple times but I didn't found any evidence.
I am not an expert nor a professional in this field, just a person who's done a fair amount of reading on the subject. With that out of the way, the idea is as follows. A barrage jammer floods a radar's operating bandwidth with noise. The success of this operation is roughly a matter of how many Watts/MHz a jammer can output. Therefore, a jammer of equal power will be more effective if it can use its full power against a range of 270MHz instead of 4000 MHz. A VHF radar is not necessarily anymore powerful in RF output than a S-band or X-band radar. In fact, based on what I read, they tend to be weaker on average in RF output. It follows that a higher frequency radar S/X-band radar has a better chance of burning through the jammer than a low frequency VHF radar.

Proportion wise VHF band is much wider than X-band after all. It is plausible that an antenna optimized for 8 GHz would work well enough at 12 GHz but an antenna optimized for 30 MHz would suck for 300 MHz. As for as I know, antenna selection is all about proportions.
I think this is called the tunable bandwidth. I would assume it would be at least as difficult for a radar to have a large tunable bandwidth as a jammer. The electronic attack aircraft could carry a specialized jamming pod against low frequency radars, like the ALQ-99 low band pod below:
1617561365000.png

Here is another example:
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Anlsvrthng

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Jamming is more complex than just a pod on the aircraft.

The jammer can't be the attacking plane, otherwise it will just give away its position, so there needs to be a dedicated aircraft in the background , on the same line as the radar-intruder.

High frequency jammers are perfect tools for passive seekers, they make the radar illumination unnecessary.

Now, problem is all modern radar road mobile, so with frequent changes of position no one can be sure where to put the jammers, and if there are multiple radars, scattered in different positions in different wavelengths the number of required jammers to make possible to hide the intruder increasing exponentially.


And to make it worst the big aperture radars has narrow beam, means the jammer needs to be in a precise position compared to the radar and the intruder, making the situation even more problematic.
 

Anlsvrthng

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The S-400 isn't really all that impressive but certainly worth studying just like Pantsir was and is worth studying for the US. So much so that the US go out of their way to procure or capture "adversary" equipment whenever and whatever they can. It doesn't mean S-400 is the best and the best China currently operates but it's likely to be way up there if not at the top for the narrow range of purpose it's designed for. The US captured and took home to test some Pantsir S-1 units and in the past many other Soviet and Russian equipment from rifles to missiles to fighters to helicopters and even submarines! This doesn't mean they wanted to copy it. Studying it and learning how to defeat certain things is more than half the value. There's still always the chance you could learn a thing or two worth applying while you're at it.
USA has more reason to try to copy the Pantsir than to found ways to counter it.

There is no usable , cheap short range air defence system, and the USA troops everywhere around the world in dire needs for such a system.
 

nlalyst

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Now, problem is all modern radar road mobile, so with frequent changes of position no one can be sure where to put the jammers, and if there are multiple radars, scattered in different positions in different wavelengths the number of required jammers to make possible to hide the intruder increasing exponentially.
You can just as well reverse this argument: aircraft are even more mobile and the defender can never be sure where to best put his mobile radars and can certainly not hope to keep up with an enemy moving an order of magnitude faster. With the initiative in the hands of the attacker, weak spots can be identified and exploited faster than the enemy can react. But this problem is largely orthogonal to the question of jamming VHF radars.
And to make it worst the big aperture radars has narrow beam, means the jammer needs to be in a precise position compared to the radar and the intruder, making the situation even more problematic.
Not in the case of most VHF radars. The only ones able to generate narrow beams are immobile and very few in number. The Nebo radar mentioned earlier could have a beam around 7.5 deg wide in azimuth (and wider still in elevation), which is several times wider than a typical search radar in S-band and an order of magnitude larger than a fire-control radar in C-band/X-band. The UHF Pave Paws AESA radar in Taiwan has a narrow beam of 2.2 deg thanks to its 30m diameter array faces with 1792 T/R elements per face. The Nebo has just 84 T/R elements.
 

gelgoog

Captain
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The Russians are developing the Nudol which should have similar uses as US GBI missiles.
There is no comparison with obsolete US Nike missiles.

The Russian S-500 seems to be a sort of counter to the US THAAD.
 
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Anlsvrthng

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You can just as well reverse this argument: aircraft are even more mobile and the defender can never be sure where to best put his mobile radars and can certainly not hope to keep up with an enemy moving an order of magnitude faster. With the initiative in the hands of the attacker, weak spots can be identified and exploited faster than the enemy can react. But this problem is largely orthogonal to the question of jamming VHF radars.

Not in the case of most VHF radars. The only ones able to generate narrow beams are immobile and very few in number. The Nebo radar mentioned earlier could have a beam around 7.5 deg wide in azimuth (and wider still in elevation), which is several times wider than a typical search radar in S-band and an order of magnitude larger than a fire-control radar in C-band/X-band. The UHF Pave Paws AESA radar in Taiwan has a narrow beam of 2.2 deg thanks to its 30m diameter array faces with 1792 T/R elements per face. The Nebo has just 84 T/R elements.
You still don't get it.

Without knowing the positions of the radars the intruder can't position the jammers.
The unknown play to the hand of the defender.

The jammer-intruder needs to coordinate they moves perfectly in regards of radar, not the other way around.


Example, 7.5 angle beam mean at 110 km two nebo can restrict the area of the intruder to 15 km zone, more than enough to cue the S band radars to the B-21/F-35.
At the same time the two jammer needs to stay in a 45 km zone at 330 km distance, and move its position relative to the radars and the intruder during the attack. If the intruder needs to change the path then the jammers needs to adjust they position and trajectory as well.
 

BoraTas

Junior Member
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You still don't get it.

Without knowing the positions of the radars the intruder can't position the jammers.
The unknown play to the hand of the defender.

The jammer-intruder needs to coordinate they moves perfectly in regards of radar, not the other way around.


Example, 7.5 angle beam mean at 110 km two nebo can restrict the area of the intruder to 15 km zone, more than enough to cue the S band radars to the B-21/F-35.
At the same time the two jammer needs to stay in a 45 km zone at 330 km distance, and move its position relative to the radars and the intruder during the attack. If the intruder needs to change the path then the jammers needs to adjust they position and trajectory as well.
Can the S-band radars track the F-35 and B-21 even if they are cued? I know long scan times increase the range considerably but can it enable a radar that is normally not capable enough to track F-35?
 

Anlsvrthng

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Can the S-band radars track the F-35 and B-21 even if they are cued? I know long scan times increase the range considerably but can it enable a radar that is normally not capable enough to track F-35?
Why do you think that a 10 cm radar can't track an f-35/B-21?
 

nlalyst

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Can the S-band radars track the F-35 and B-21 even if they are cued? I know long scan times increase the range considerably but can it enable a radar that is normally not capable enough to track F-35?
Theoretically it is possible, but in reality it is complicated. First of all, a large stealth bomber like the B-21 or B-2 may not even be more detectable with a VHF radar like the Nebo than with an S-band radar like the Big Bird. In fact, the S-band radar may very well have a better chance of detecting them due to higher output power and superior antenna gain.

At long ranges, the opportunity for pulse integration is reduced, because the radar has to operate at a lower PRF. If there is fluctuation in target RCS that will further reduce the probability of detection. If there are decoys flying in tandem with the stealth bomber that will reduce the probability of detection even further. Weather conditions can further degrade radar performance, as can jamming, etc.

Ideally you would want to paint them from high off center axis angles, but that may be difficult. Stealth aircraft are very well optimized for +/- 60 deg angles of incidence.

Bi-static and multi-static radars are often mentioned as a superior method for detecting stealth aircraft t than mon-ostatic radars. They also have the advantage that the passive components of such radar systems will be difficult to detect and less prone to jamming.
 

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