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Discussion in 'Navy' started by Jeff Head, Apr 6, 2015.

  1. Tetrach
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    Tetrach Junior Member
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    then, why "wasting" so much money on large radar panels when other nations seem to use much more practical designs without a drop of efficiency ?
     
  2. Iron Man
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    It could be a number of reasons for a larger panel. Greater resolution and greater utility are likely among them. The more T/R modules you have the more you can subdivide into specific tasks, for example.
     
  3. Tam
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    Tam Senior Member
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    They don't necessarily agree with the same path to achieve he same result. The same thing happens with air defense systems.

    The previous post already explained it. Also in addition, phase arrays lose transmit gain when the beams are angled over 60 degrees from the center, creating weaker gaps between the faces of a four faced radar. Thus rotating to eliminate these gaps, such as with SAMPSON, EMPAR and Kronos. However, for rotating radars are a bit easy to predict with EW, but most importantly are subjected to mechanical stress, so mechanical areas are points of failure. The rotating radar cannot be accessed easily to have a module replaced inside like that of an integrated mast (APAR) or deckhouse (Type 346) can.

    APAR differs from the other radars is that it functions as a fire control radar, the others are mainly search radars that are capable of a weapons quality track. The real search radar on ships using APAR is the SMART-L radar that these ships also have.

    The lower horizon coverage of the Type 346 radars are offset on ships like the Type 052C/D with the Type 364 radar ---- the globular radome on top of the mast --- on these ships. The Type 364 radar appears on most PLAN ships. However, this is a mechanical radar with a parabolic array, so it doesn't have the benefits you have with a phase array or AESA.

    You have not seen other forthcoming designs yet. Like three faced EADS for USN FFG(X).

    Just on the countries using the Type 26 frigate design, they don't agree on the radar set up used.

    Canada-Type26-1014x487.jpeg maxresdefault.jpg

    Type-26-Global-Combat-Ship-sea5000-725.jpg
     
  4. Tetrach
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    Tetrach Junior Member
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    okay thanks you, but I still don't understand why the americans and chineses are installing impractical large radar panels on their ships when european shipbuilding companies just put smaller radars on the top of the last of their ships.

    A rotating Radar seems much more practical even if lose surety and gain mechanical stress. How can a tiny rotating radar be comparable in performances with 4 large panels (what is the advantage of more T/R) ?
     
  5. Tam
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    Tam Senior Member
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    When you have more and equal number of phase shifters in elements in X and Y axis, you can tighten the main lobe, and that results in greater transmit gain and less side lobes. You get greater detection range, better angular resolution from better directivity from narrower beams, and less sidelobes, which is wasted energy that is detectable by enemy passive detection systems. So yeah, the bigger the better. Plus more elements means power per element and more overall power. Those FCRs serving S-300 and S-400 systems have as much as ten thousand elements, AN/TPY-2, which is used for ballistic missile intercepts, has as much as 25,000 elements.

    Rotating radar now seems to be good only for budgetary reasons to avoid the cost of a fixed four face radar. The European trend is towards smaller four faced radars but placed high above the bridge embedded in an integrated mast that allows repair access inside the mast. The British is still retaining the rotating radar act, with SAMPSON giving way to Artisan 3D, but Thales Herakles, Leonardo Kronos and EMPAR, which are all rotating radars, have given way to successors that are fixed radars, like Advanced Kronos and Thales Sea Fire. Cassidian TRS-4D is offered in both four faced version, like used in the German F125 frigate, or in rotating version, which will be used in Freedom class LCS after the 16th ship. Its predecessor, the TRS-3D, which is used on German corvettes and the USN Freedom class LCS, is a single faced rotating radar. So in Europe, there is a clear trend towards four fixed faced radars. You can also see the Russians (Poliments), the Canadians and the Australians (CEFAR) headed on the same direction too.


    p1723242.jpg maxresdefault (1).jpg


    TRS-4D-Fixed-Panel.jpg

    The smaller size of some European radars, are due to a higher frequency band, like Thales APAR, which is X-band, and Leonardo Kronos and Cassidian TRS-4D are C-band. Element spacing is about 1/2 the wavelength used, so if you use 10 cm S-band wavelength, your element spacing is 5 cm in the side facing the array. If the element is 5 cm C-band wavelength, the element is 2.5 cm. If the wavelength is 3 cm X-band, the element is 1.5 cm. .However, the smaller radar isn't cheaper when it has the same number of elements of the bigger radar.

    Do note you cannot make direct comparisons between S-band vs. C-band vs. X-band radars as they all have separate roles to fill, and this also includes L-band and K-band radars. The presence of large Chinese and US S-band radars means that the Chinese and the US emphasize broad, large volume and high range searches and sweeps that favor early detection of large waves of aerial assault, while the Europeans, with their smaller radars on high masts, are prioritizing early sea skimmer antiship missile detection by enlarging their radar horizons using increased height. This also has to do with the US and Chinese warships wielding these large radars are classified as destroyers, while the European warships wielding these smaller higher masted radars are classified as frigates and are not as large nor as well armed.

    The Chinese and the US do have secondary sea skimmer spotting radars on their ships but these are mechanical rotating radars that don't have the full advantage of AESAs to their role. Eventually these secondary sea skimmer spotting radars will be replaced by AESA designs.
     
    #395 Tam, Apr 6, 2019
    Last edited: Apr 6, 2019
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  6. Biscuits
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    Biscuits Junior Member
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    Does the Type 055 have such secondary AESA radars? It’s mast has four panels on them in addition to the “normal” radars on the side of the ship.
     
  7. Iron Man
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    Nobody on the internet really knows what those 3 integrated panels on each facing of the 055's mast are for. The standard guess is that the lowest and largest panel is an X-band AESA used for precision search, horizon search, and target illumination, while the 346X panels on the hull are S-band for volume search, tracking, and maybe midcourse guidance ala SPY-1, having perhaps shed the C-band component present on earlier iterations of the 346. The 2 higher, smaller panels are harder to guess at IMO. My guess is comms antenna judging by similar panels on the Zumwalt, like Ku-band T/R panels, or maybe a datalink like the CEC, or maybe ESM. In addition there are 3 additional smaller objects on the mast below the largest panel. It's likely there is some combination of E/O sensor and navigation radar in those modules, along with something else.
     
    #397 Iron Man, Apr 6, 2019
    Last edited: Apr 6, 2019
  8. Tam
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    Tam Senior Member
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    Yes as previous post explained. In addition, there are those above the bridge. Note #4, plus #8 and #9.

    2017-07-10-Quelques-hypothèses-sur-les-senseurs-du-destroyer-Type-055-02.jpg



    For the US, this is AN/SPY-6. Described as DBR or Dual Beam Radar, SPY-6 is S-band, while the X-band is furnished by SPQ-9B on top. SPQ-9B is a mechanically rotating, dual faced slotted array however, and is meant as a stop gap, as they have not done an X-band AESA component for it.


    17435918-10155181895619936-4582928273722705252-o-orig_orig.jpg


    Also bears in comparison with the Zumwalt. The larger square is for the S-band SPY-4, but is eventually deleted from the final ship because of the sheer cost. The smaller square on top is for the X-band SPY-3 which is retained. Strip bar on the bottom is IFF. On the Ford class carriers, both SPY-3 and SPY-4 panels are retained.


    img07-040-02.png



    The original vision of AMDR is like this. S-band radar on deckhouse, while X-band is on the integrated mast.


    maxresdefault (2).jpg


    Final Flight III AB ended up like this. They took out the X-band on top because it was too expensive. Instead, they placed the X-band SPQ-9B aka "Spook-9" on top to serve as a sea skimmer spotter and gunnery radar. Despite being a fire control radar, Spook 9 does not illuminate for missiles, which is why SPG-62 is retained through out the ship. SPQ-9B is currently not on Flight II or Flight IIA AB, but its on the Ticos.


    2j136s2.jpg


    AN/SPS-67 is currently used a seaskimmer spotter for earlier and current Flight of Arleigh Burke.

    https://en.wikipedia.org/wiki/AN/SPS-67

    I want to bring up past, current and future iteration of Arleigh Burke to compare to the European and Chinese solutions to provide context in comparison.
     
  9. Tam
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    Tam Senior Member
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    The current PLAN solution, other than the Type 055, for sea skimming spotting is this, the Type 364 with the export name of SR64. To explain further, that despite the low position of the Type 346 radars, PLAN warships are not left naked to sea skimmer threats.



    200452714545719 (1).jpg

    Located like this.


    type-051c-luzhou-ddg-systems1.png


    Note that in other ships, the position of Top Plate and Type 364/SR64 is reversed, like on the Type 054A and 051B refit.


    spd4sw.jpg


    In addition to Type 364, 'Band Stand', 'Rice Lamp' and the Type 517 are also situated higher than the Type 346 and might be able to spot sea skimmers.

    Type 364 also cues HQ-10 launcher and the CIWS towards threats.
     
  10. Tetrach
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    Tetrach Junior Member
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    Okay, thanks you very much Tam and Iron man !

    Is it actually possible to subdivide a single radar panel into different surfaces to multiple the number of tasks executed at the same time ?

    So the size of a T/R module depends of its frequency ?
     
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