Naval missile guidance thread - SAM systems

[Blitzo]

Or rather, let's put it this way.

The primary advances in technology and capability that a SPY-6 offers versus other existing S band AESAs is that the SPY-6 features GaN (enabling significantly greater power and range and fidelity) and benefits from modern contemporary back end systems and software.

But for the purposes of discussing guidance mechanisms -- the SPY-6's new capabilities does not actually offer anything new to the conversation.
Yes, SPY-6 features longer range, the ability to track more targets, more power, and so on, however it doesn't provide a fundamentally different way of guiding missiles which did not already exist aboard prior ships with similar radar set ups.

If a Flight III Burke with SPY-6 wants to guide and launch an SARH missile such as SM-2 or ESSM Block I, it will still need onboard illuminators in the form of SPG-62s for the initial batch of ships. The overall mechanism of detection, track, launch, midcourse guidance and terminal illumination is barely different to that of a pre-Flight III Burke with SPY-1.
If a Flight III Burke with SPY-6 wants to guide and launch an ARH missile such as SM-6 or ESSM Block II, its overall mechanism of detection, track, launch, midcourse guidance and terminal guidance is also barely different from a pre-Flight III Burke with SPY-1 launching the same missiles. Furthermore the overall mechanism of detection, track, launch, midcourse guidance and terminal guidance is also barely different between those ships and other ships equipped with S band AESAs and ARH SAMs such as the Type 45 which features SAMPSON and ARH guided Aster missiles.


In other words, the enhanced capabilities that SPY-6 offers compared to SPY-1 or even other S band AESAs using GaA (like SAMPSON) is not relevant to the conversation, fundamentally because the SPY-6 doesn't offer any new or unforeseen guidance mechanisms which already existed.


SPY-6 is obviously a more capable radar than SPY-1 and older AESAs like SAMPSON, which will provide commensruate advances in overall combat capability.
But that is largely irrelevant to the goal of examining international guidance mechanisms and to try and ascertain the guidance mechanism of 052C's Type 346A (and 052D and 055 after it).




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Now, with that out of the way, I think there are a few major contemporary missile guidance mechanisms we see used most often internationally, which I think can be categorized based on the primary MFR + the presence, type (or lack of) terminal illuminators + the missile guidance system itself.


1: "slow" rotating phased array in S band or near C band + presence of mechanically steered terminal illuminators + SARH SAMs.
Ships in this category include the various Russian and Chinese ships that rely on Fregat and Orekh illuminators or derivatives (Grigorovich, Talwar, Sovremenny, 054A), but also some legacy western ships such as the Kidd class destroyer and also older destroyers and cruisers like the Leahy class and Virginia class, and other ships that received the new threat update.
These ships are not as capable as any of the subsequent categories, and technologically speaking is the least sophisticated and least capable (when all else is held equal)

2: fixed or fast rotating phased array in S band or near C band + presence of mechanically steered terminal illuminators + SARH SAMs.
Basically the only ship in this category are ships equipped with the aegis combat system; your Burkes and Burke derivatives and Ticonderogas and so on. Technically, even Flight III Burkes with SPY-6 and SPG-62 that uses SARH guided missiles like SM-2 or ESSM Block I will be included in this category.

3: fixed or fast rotating phased array in S band or near C band + ARH SAMs (no mechanically steered terminal illuminators)
There are many ships in this category. Type 45, Horizon, Kolkata, Sa'ar-6, are included, and they all feature SAMs that are ARH guided.
But all aegis equipped ships no matter whether they use SPY-1 or SPY-6, can also be included in this category if they are fielding ARH SAMs like SM-6 or ESSM Block II, because an SPY-1 can guide ARH SAMs just as an SPY-6 can.

4: fixed or fast rotating array in X band phased array acting as an illuminator + L band volume search radar + SARH SAMs -- (no mechanically steered terminal illuminators)
Ships in this category are basically the European frigates equipped with a combination of Thales APAR (X band), and SMART-L (L band), and SARH SAMs like ESSM Block I or SM-2. De Zeven, Sachsen classes among others are included in this category. The X band phased array (APAR) is used as a more advanced terminal illuminating radar than multiple mechanically steered terminal illuminators like SPG-62 or Orekh.

5: fixed or fast rotating phased array across multiple bands (S band and/or near C band and/or X band and/or L band) + ARH or SARH SAMs -- (no mechanically steered terminal illuminators)
There are a few ships in this emerging category, which may feature phased array radars across two or more bands.
Ships in this class lacks mechanically steered terminal illuminators, but use phased array radars in X band or C band to provide guidance to SARH SAMs, however are also able to provide guidance to ARH SAMs as well (which obviously doesn't require terminal illumination or additional terminal guidance channels).
Existing examples of ships in this class include the upgraded Australian ANZAC class frigates with CEAFAR/CEAMOUNT radars, also the Japanese Akizuki and Asahi class destroyers.
Emerging ships like the Spanish F110 class and the Italian PPA will also have multiple sets of phased array MFRs operating across different bands.
The Flight III Burke batch which eventually gets an X band phased array radar will also fill this category as it will replace SPQ-9B and SPG-62s with a new X band AESA, giving it a dual band phased array radar capability.
The future Australian Hunter class frigate will also feature a more expansive multi band radar system than the CEAFAR/CEAMOUNT used on its ANZAC predecessors, potentially including an L band array.
---- all ships in Category 5 are capable of launching SARH or ARH guided missiles; however when they guide SARH missiles the important distinction is that they don't use mechanically steered terminal illuminators, but rather modern phased array (AESA) radars operating in the relevant band (mostly X band). Given most of these ships are quite modern or emerging, it is likely that their primary SAMs will be ARH guided, but the fact that most if not all of them have an X or C band AESA, they are still able to guide older legacy SARH guided SAMs.
Ships in Category 5 offer the most capable combination of sensors and guidance options compared to prior categories.

Note, ships in Category 4 can in theory be folded in with ships in Category 5, with the only major difference being that ships in Category 4 all feature much more common sensor and weapons outfits than the different ships in Category 5, and also because the ships in Category 4 do not use any ARH guided SAMs at present.
It would be a very reasonable argument if one wanted to suggest that ships in Category 4 and 5 could be considered under the same umbrella, particularly if ships in Category 4 are equipped with ARH guided missiles.


IMO the above 5 categories are the most proliferative "categories" of missile guidance concepts for the world's naval AAW ships, and while it isn't entirely exhaustive, I think they capture a good majority of the guidance mechanisms that the most prominent ship classes and hulls use.

As we can see, the differences in the major 5 (or 4) categories above is a result of a different permutation of the below factors.

• - primary radar type -- i.e.: slow rotating phased array or fixed/fast rotating phased array? And it features fixed/fast phased arrays, does it feature multiple phased arrays across multiple bands or only one phased array across a single band
• - presence or lack of presence of mechanically steered terminal illuminators? And if it lacks mechanically steered terminal illuminators, does it feature a phased array system operating on a relevant band to provide terminal illumination capability?
• - missile types that can be guided -- SARH only, or ARH only, or is a ship capable of using a guiding both SARH and ARH?

So the question is -- where does the 052C, 052D and 055 and their respective missile guidance systems likely fit in among those categories, and/or are any of 052C, 052D and 055 equipped differently in a way that they are in their own category?

 

[Max Demian]

...
So the question is -- where does the 052C, 052D and 055 and their respective missile guidance systems likely fit in among those categories, and/or are any of 052C, 052D and 055 equipped differently in a way that they are in their own category?

Nice categorization. However it's missing the fact that for SARH guidance in X-band band you need CW capability. Not all X-band radars are automatically suitable for this role, as search and track radars typically operate in pulsed mode.

To come back to your question, one of the original theories regarding Type 346 on 052C is that it is a C-band radar, based/assisted by Ukrainian technology/design from the KVANT bureau. The hypothessis was that the radar has bith search/track and illumination capability (ICWI?). Another connection could be made to the HT-233 radar, used in the HQ-9 SAM system.

 

[Max Demian]

Just for the sake of argument, can it be ruled out that the Type 346 on 052C is an engagement radar only?

 

[Tam]

ESSM Block I needs external guidance because they don't have internal sensors. They are short to medium range missiles against OTH sea skimmers and X band are more suited due to sea clutter. Such an architecture is a product of past technology. Their shortcomings are being addressed through Block 2 which dispense with their reliance on any external sensors. It is a function of history, past technology adoption, missile form factor and the nature of the threat and not necessarily an issue specific to SPY-6..

This is incorrect and as Blitzo already pointed it out. ESSM Block 1 still has radar sensor, what it doesn't have is an emitter. So someone or something has to shine the target like a flashlight so the missile is drawn to it. That's your target illuminator. In the AEGIS case, its the SPG-62. Other systems have their own illumination approaches. The RF emitted from the SPG-62 bounces off the target to the sensor on the ESSM, or Standard missile. The missile homes in on the reflection. With active radar guidance, the emitter is on the missile itself. With the missile working this way, it no longer needs a shipboard illuminator.

Typically with semi-active guidance, your engagement numbers are limited by the number of illuminators. If you have three illuminators on board then you can only engage three at one time until each target is destroyed. Your engagement envelope is limited by the range of the illuminators, as well as their arcs, their line of sight and radar horizon, and the mechanical speed the antennas can turn around if these are not phase arrays. But this method does have its advantages, if within range shipboard illumination is much more powerful than a battery powered portable emitter unit inside your missile's head, and it can easily burn through ECM and other clutter. You also have more control of the entire kill loop. One collateral benefit is that SARH method might be better against low RCS targets due to not only that shipboard illumination is much more powerful, but stealth directional shaping is intended to reduce and deflect the echo away from the emitter. However with SARH, the receiver on the missile is not the same location as the shipboard emitter.

While ARH missiles isn't limited by shipboard illumination, its still limited by the number of channels the datalink can host. ARH is not completely autonomous, it is only true forget at the terminal stage. The radar emitter and receiver on the missile is small, battery powered, so the range of the seeker is limited. This cone is the missile's 'kill basket'. So hypothetically, if a missile has a range of 200km, but the seeker's range is about 20km, you still have to guide the missile from launch to somewhere close enough for the target to be within the missile's basket. That's where your shipboard radar has to come in, it still has to guide and tell the missile where to go until it is close enough to bring the target to the missile's catch basket. The seeker activates, and from this point on, the missile is truly autonomous and homes in to the target.

The job of bringing an ARH missile to the within range of the missile's basket can be more than fulfilled by radars like SAMPSON, EMPAR, and MF-Star. I have no doubt that it can be fulfilled with the SPY-1 family, with the fire control system updated in software to take account for active homing. SM-6 is already an active homing missile, and the latest block of Standards are dual seeker, with a SARH seeker and an IR seeker --- even taking account of infrared vs. radar, the basic idea is the same, the radar guides the missile until the target is in range of the infrared seeker before letting it go live. This allows all Burkes to take advantage of active guided missiles without having to upgrade to SPY-6, as most Burkes cannot; only more recent ships built after 2010 have the infrastructure for the new radar.

Even with active guided missiles, the ship's radars and combat systems must still have an element of control. You don't want all of your missiles launched to all head to the same target for example, you want to make sure each missile heads to the separate target designated to each.

Going back to the SARH principle, an S-band radar itself cannot illuminate a target because the missile's antenna is that small, and an S-band width is too large for such a small antenna to get enough angular accuracy. Note that we are not comparing the width of the wave vs. the cross section size of the target, we are talking about the small antenna on the missile seeker. So the shipboard S-band radar queues a separate emitting source radar, an X-band illuminator to light the target and supply the radiation for the missile's seeker. AESA or GaN has nothing to do with it. That's why for legacy missiles, a ship equipped with the SPY-6 still has to use SPG-62.



Note that AEGIS is exceptional for SAM systems given that SPG-62 are pure emitters and have no receive capability. They need to be constantly directed by the SPY-1. The beam only goes one way. With other systems for example, like the S-300's Flap Lid or Tombstone, the Front Domes used on the Shtil-1 and HHQ-16, systems like Thales STIR and Thales APAR, Raytheon's MPQ-53 for the Patriot, these are complete radars and they track targets and illuminate them on their own. The search radars acquire the targets, sends the info to the fire control radars, which work separately to track the targets and stay glued on them.

 

[Tam]

Just for the sake of argument, can it be ruled out that the Type 346 on 052C is an engagement radar only?

Nope.

You are left with a ship that has no volume air search radar.

 

[Tam]

Nice categorization. However it's missing the fact that for SARH guidance in X-band band you need CW capability. Not all X-band radars are automatically suitable for this role, as search and track radars typically operate in pulsed mode.

To come back to your question, one of the original theories regarding Type 346 on 052C is that it is a C-band radar, based/assisted by Ukrainian technology/design from the KVANT bureau. The hypothessis was that the radar has bith search/track and illumination capability (ICWI?). Another connection could be made to the HT-233 radar, used in the HQ-9 SAM system.

That's Western analyst theory, with anti-Chinese bias --- yes that needs to be called out --- which means fake news.

Only data relevant are the ones coming out of China, and if that cannot be trusted, the analysis on the equipment itself as physically seen. While data can be sparse, no data is better than fake news, because a blank slate keeps us curious and searching for the truth.

 

[Max Demian]

Note that AEGIS is exceptional for SAM systems given that SPG-62 are pure emitters and have no receive capability. They need to be constantly directed by the SPY-1. The beam only goes one way.

This is something I've been wondering for a while. How is the SPG-62 actually slaved to SPY-1? I mean, what control mechanism ensures that SPG-62 points to where the SPY-1 is pointing or telling it to point and keeps staying on target, if the SPG-62 has no receive capability?

 

[Max Demian]

To elaborate on my post #57.

One idea I had was a combination of inertial navigation systems built into the illuminator and a predefined zero position into which the illuminator settles to zero out errors. This means that the illuminator needs to settle back into zero position after some time t, otherwise the pointing errors become significant.

But I don't think this is enough. The zero position could be compromised due to a variety of effects, including battle damage. So an additional system, perhaps laser based is needed to track the illuminator/zero position and keep it calibrated to the ship coordinate system.

 

[Tam]

This is something I've been wondering for a while. How is the SPG-62 actually slaved to SPY-1? I mean, what control mechanism ensures that SPG-62 points to where the SPY-1 is pointing or telling it to point and keeps staying on target, if the SPG-62 has no receive capability?

I don't know how they do it, just that they do it.

 

[Anlsvrthng]

The simple answer is cost The long answer is about trade offs relative to the nature of the threat, capabilities and cost of solution.

The radar typically has a narrow antenna beam which allows it to determine the azimuth and elevation of a target. The more accurately the radar must know the location of the target, the narrower the beam. The cross range dimension of a radar’s resolution cell is generally accepted to be the 3-dB antenna beamwidth. In simple terms, the larger the beamwidth the faster is the search but the constraining factor is the necessary resolution cell needed to discriminate its target at a given distance. We don;t know the details but the John Hopkins technical digest is of the opinion that the AMDR-S band has sufficient fidelity relative to the required task. An X band would be preferable but S band is more cost efficient.

Angular resolution is not produced with the main beam, that would produce useless results (several km big spot ) .

The best method is monopulse , in the case of phased array they break the antenna to 2-4 subgroup, and generate 2-4 beam, with different characteristic.

The angular resolution of them is quite good, in the range of range resolution actually.

10 m angular resolution at 100km .

. According to public data SPY-1(V)D has a detection range in excess of 310 kms against a missile of 0.03m2 RCS. The AMDR has been verified to achieve a 20dB in test and that translates to a 3.2 times distance to that of SPY-1(V)D and that is approximately 1000 kms. This gives an added depth of 690 kms to the defensive bubble for BMD.

I love it .

So, the SPY-6 can detect an F-35 from hundred(s) of km, but the 30% bigger Big Bird can't do it : )

In contrast, the S1850M installed on the Type 45 and Horizon destroyers are to my knowledge not BMD capable. Its stated detection range is only 400 kms but that is against a fighter size target which means anything between 1 to 3 m2 in RCS. It is D band which is L band equivalent of between 1 to 2 GHz This give rise to a range resolution of between 1.5 m to 75 cm and would be questionable fidelity for missile discrimination based on the discussions above. Based on these specs its detection range is only approximately 126 kms against a missile with RCS of 0.03 m2. While the Type 45 is a very capable area air defence platform, it is simply not in the category of the AMDR. Facts do matter. .

Finally on the issue of propagation loss it is not entirely relevant because in the overall conversation the radar equation incorporates this variable to derive the end state of range. As a point of note I have a graph below that charts the difference in spread loss between a S and X band frequency over a 500 kms range

View attachment 57551

The radar cross section different on different frequencies.

A missile radar cross section will be bigger on D/L band than on S band, and will be very small on X band.
With monouplse they can lock the target into a 100(s) meter big cube from 100-200 km ,enough for a missile to be directed to the target.

Reason why the JY-26 is tall, they want to get altitude data for missile guidance.