056 class FFL/corvette

Status
Not open for further replies.

Tam

Brigadier
Registered Member
Even if it's EW, it can be deactivated for a duration of the rotation to avoid interference.

But, as you can see from the below photo, the possible EW antenna is actually placed below H/LJQ-363, out of its line-of-sight. Also judging from the photo below, H/LJQ-363 is placed some distance away from the pole, which doesn't appear to block that many degrees of arc in the rear aspect.

Type_056_corvette_in_ShangHai.jpg

That antenna below the Type 364 is an RWR, its not a transmitting antenna. Its just a passive receiver.

The "tree" behind the Type 364 happens to have branches, and there are stuff on them that could either be for communication or EW.

If the Type 364 is not sending/receiving during that arc, that would still be significant, which may explain why you need the fourth navigation radar to track down the helicopters.
 

Tam

Brigadier
Registered Member
That example of mine was bad. I was thinking of a top-mounted phased array that scans elevation electronically, which also has the added benefit of better coverage for aerial targets.

You want an array that scans both low and high. The top array is an inverse or twist cassegrain. As it spins, it uses polarization to refract the radio waves down, then up, then down.

phao-ham-type-730-ciws-tau-type-052d-datviet.vn-02_11412621.jpg
 

by78

General
That antenna below the Type 364 is an RWR, its not a transmitting antenna. Its just a passive receiver.

The "tree" behind the Type 364 happens to have branches, and there are stuff on them that could either be for communication or EW.

The stuff on the tree are far too small to be EW antennas. They are likely ESM arrays. The location is ideal, and since these are passive, they don't interfere with the radar.

You want an array that scans both low and high. The top array is an inverse or twist cassegrain. As it spins, it uses polarization to refract the radio waves down, then up, then down.

View attachment 46799

There's no evidence that's an inverse Cassegrain radar. And what do you mean it spins? What spins?
 

Tam

Brigadier
Registered Member
The stuff on the tree are far too small to be EW antennas. They are likely ESM arrays. The location is ideal, and since these are passive, they don't interfere with the radar.

The radar interferes with them however. Unless the radar stops functioning as it turns towards them and not just directly, the radar has to stop functioning right at some distance off before it faces the arrays directly, because the radar's side lobes will interfere these arrays. You can't wait before the radar's main lobe to touch these arrays.

And yes, these arrays do interfere with the radar because they will reflect back the radar beam.


There's no evidence that's an inverse Cassegrain radar. And what do you mean it spins? What spins?

Type 344 and Type 347 are known inverse or twist cassegrains and just the sheer appearance of it already tells that. If you look at the back of the radar, that's a parabolic, and the front of it is a polarization lens and the reverse parabolic reflector. The feed horn is behind the main reflector, shines at the secondary reflector, which reflects back to the main reflector, which reflects outward to form the main beam. In a twist cassegrain, the feed horn is off to side, the main reflector is tilted, and as the disk is spun like a record, so the direction of the main beam changes. Inverse cassegrains are common with fire and gun control radars because they are fairly small, and little to no space is needed for mechanical scanning.
 

by78

General
The radar interferes with them however. Unless the radar stops functioning as it turns towards them and not just directly, the radar has to stop functioning right at some distance off before it faces the arrays directly, because the radar's side lobes will interfere these arrays. You can't wait before the radar's main lobe to touch these arrays.

And yes, these arrays do interfere with the radar because they will reflect back the radar beam.

I beg to differ, they are placed well out of the way.

41389651224_babf7a54c1_b.jpg
 

by78

General
Type 344 and Type 347 are known inverse or twist cassegrains and just the sheer appearance of it already tells that. If you look at the back of the radar, that's a parabolic, and the front of it is a polarization lens and the reverse parabolic reflector. The feed horn is behind the main reflector, shines at the secondary reflector, which reflects back to the main reflector, which reflects outward to form the main beam. In a twist cassegrain, the feed horn is off to side, the main reflector is tilted, and as the disk is spun like a record, so the direction of the main beam changes. Inverse cassegrains are common with fire and gun control radars because they are fairly small, and little to no space is needed for mechanical scanning.

Known by whom? Do you have a source? And yes, I have X-ray vision to look behind the RF-transparent cover to see that it's indeed a inverse Cassegrain. In reality I have no such powers, but the shape of it looks suspiciously like a regular Cassegrain, with the main parabolic reflector in the back, and the hyperbolic sub-reflector in front.
 

Tam

Brigadier
Registered Member
I beg to differ, they are placed well out of the way.

41389651224_babf7a54c1_b.jpg


The beam interference already begins even before the main beam (or lobe) would hit the spine, because of the radar generates side lobes that goes out in all directions. They would reflect back to the dish even if the dish is not fully pointed at the spine. Hence the array would stop radiating at some point before these side lobes --- which also extend upward and downward --- would hit the ESM receivers. That still leaves a cold blind spot in the rear which has to be picked up by the aft navigation radar.

If the antenna has an ultra low side lobe design, like you may expect with phase and planar arrays, you can expect less side lobe echoes and realize a longer activation period before the antenna faces the spine.
 

by78

General
The beam interference already begins even before the main beam (or lobe) would hit the spine, because of the radar generates side lobes that goes out in all directions. They would reflect back to the dish even if the dish is not fully pointed at the spine. Hence the array would stop radiating at some point before these side lobes --- which also extend upward and downward --- would hit the ESM receivers. That still leaves a cold blind spot in the rear which has to be picked up by the aft navigation radar.

If the antenna has an ultra low side lobe design, like you may expect with phase and planar arrays, you can expect less side lobe echoes and realize a longer activation period before the antenna faces the spine.

Right, and of course the frigate possesses little signal processing capabilities that compensate for such interference, in the unlikely event that it occurs. In fact, I'm beginning to think the Chinese RF engineers didn't understand the interference issue at all, which is why they have placed the radar in such a terrible spot. To compensate, they've decided to jury-rig a FCR and crammed it in a small recess underneath the HQ-10 launcher, forgetting to or failing to put it on top of the launcher, which would be the ideal location. Or alternatively, they've decided to magically use 2D navigation radars to somehow acquire elevation data for the HQ-10.

Or, maybe there's no FCR underneath the missile launcher after all, because it doesn't need it, since the type-364 already serves that function, with no blind spots.

Why jump through so many increasingly ridiculous hoops to justify a mistake? Choose the simpler and more dignified path.
 
Last edited:

Tam

Brigadier
Registered Member
Right, and of course the frigate possesses little signal processing capabilities that compensate for such interference, in the unlikely event that it occurs. In fact, I'm beginning to think the Chinese RF engineers didn't understand the interference issue at all, which is why they have placed the radar in such a terrible spot. To compensate, they've decided to jury-rig a FCR and crammed it in a small recess underneath the HQ-10 launcher, forgetting to or failing to put it on top of the launcher, which would be the ideal location. Or alternatively, they've decided to magically use 2D navigation radars to somehow acquire elevation data for the HQ-10.

Or, maybe there's no FCR underneath the missile launcher after all, because it doesn't need it, since the type-364 already serves that function, with no blind spots.

Why jump through so many increasingly ridiculous hoops to justify a mistake? Choose the simpler and more dignified path.

Of course the frigate has signal processing capabilities. The thing is, the main radar is using one of the most common used military bandwidths in the most commonly used purpose, which is search. And then you have every warship, both friendly and enemy, using the same band. How can you detect and distinguish the signals of others when your own signals is shining right next to them? Its possible if the Type 364 is doing a full 360 degrees, the ESMs are deactivated, and if the ESMs are operating, the main search radar is deactivated (read the last paragraph.)

The elevation of the Type 364 radar are also limited, as it doesn't scan vertically like phase arrays or planar arrays do. Its mainly meant for surface search, and will catch low flying targets collaterally like any 2D radar do. I never said that I am happy with this choice of radar, and actually I feel more like criticizing it. A full 3D search radar with vertical scanning that's a phase array or AESA can be available for this ship if the PLAN wants to, code named SR2410C, and its been installed on export Type 056s for Bangladesh. Its not as if the designers are unaware of it, they quite are, and probably wish the new radar to be installed on future PLAN Type 056s.

The radar rotates around 30 RPM. That's how fast it updates its picture. If you have a fast incoming target, that's won't be fast enough to track it accurately. This isn't the best type of radar for precise tracking against fast moving and close threats.

I never said anything about the 2D radars trying to acquire elevation data. All these radars are meant to scan the surface.

This has been said to you more than a couple of times. An FCR underneath the launcher would not require the launcher to be depressed to scan for low surface sea skimmers. With the launcher in a not depressed position, the missiles can be fired at an arc that can achieve greater range. The FCR would also have a much higher scan rate that isn't limited in dwell and updates by mechanical rotation. The FCR can be small, work via continuous wave illumination, gives an endless uninterrupted stream of real time updates that measures range very precisely. A CWI radar is very compact, that's why they're used in missile seeker heads, used as radar guns for speeding cars, used in the back of the cars to aid parking. You don't need a search or a full blown tracking radar on top of the launcher, all you need is a CWI unit. If you are adding a search radar function to a CIWS, it would be convenient to put it on top yes, but we're not looking to add a search function, we are looking to add a fire control function. You already got your search radars somewhere.

Finally you keep losing the purpose of the warship. You got all these radars doing surface search, because that's where its main concern and threats are --- catching submarines on the surface, opposing surface ships which can range down to fast patrol boats, gun boats, and FACs, and the missiles they will fire will almost certainly be of the sea skimmer variety.

So even if the Type 364 and the navigation radars do pick up a surface threat, they may still need to queue in a much faster tracking FCR type radar towards the target, as these radars are primarily search radars. They are not meant for the fire control function. That's basically how the SAM control chain works. Search Radar (1) -> Tracking or Fire Control Radar (2).

Two RWRs are behind the HQ-10 to locate and triangulate for radar emitting threats. You can assume the ship also uses tactics where it has gone completely radar silent and in stealth mode --- the ship uses a stealthy design for a reason. All the radars are deactivated and the ship will rely mainly on its RWRs and ESMs for threat detection. The guns are still supported by EO, and the missiles work through a thermal and an HOE (home on emissions) mode. I should add that the two 30mm guns in the side have EO and can be controlled remotely, which means the EO's view can be viewed from a tactical room, and its possible from there the controller can also queue the missile launcher using the same data, assuming the CMS can do that.
 
Last edited:

bruceb1959

Junior Member
Registered Member
Right, and of course the frigate possesses little signal processing capabilities that compensate for such interference, in the unlikely event that it occurs. In fact, I'm beginning to think the Chinese RF engineers didn't understand the interference issue at all, which is why they have placed the radar in such a terrible spot. To compensate, they've decided to jury-rig a FCR and crammed it in a small recess underneath the HQ-10 launcher, forgetting to or failing to put it on top of the launcher, which would be the ideal location. Or alternatively, they've decided to magically use 2D navigation radars to somehow acquire elevation data for the HQ-10.

Or, maybe there's no FCR underneath the missile launcher after all, because it doesn't need it, since the type-364 already serves that function, with no blind spots.

Why jump through so many increasingly ridiculous hoops to justify a mistake? Choose the simpler and more dignified path.


I have read through this exchange and wonder why you insist on being so adversarial. It is one thing to question others thoughts but you go above and beyond. What is more laughable is that at the start of the exchange it was conceded that the box like structure under the missiles was most likely an AC unit for missile and seeker head cooling, but you ignored this and continued to chase down the radar route, all the while dismissing everything that was said. And then most laughable of all right at the end you come out with 'maybe there's no FCR under the missile launcher'.... circle completed. <rolls eyes>
 
  • Like
Reactions: Tam
Status
Not open for further replies.
Top