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

  1. Tam
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    Tam Senior Member
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    Yes and yes.

    For the second question, it should be with one of the dimensions of the module facing the array itself connected to an antenna (dipole, monopole, plate, notch, gate slot, etc,.)

    Do note there are things like DTRMs and QTRMs, which means Dual T/R Module and Quad T/R module. In which case, the spacing between the T/Rs themselves must be half of the wavelength. DTRMs and QTRMs are meant to reduce AESA costs. For a QTRM you have one LNA for four transmitters, instead of one LNA per transmitter on a TRM.

    For example this is a QTRM. The distance between each T/R in this module should be half the wavelength and should give you an idea what spectrum this operates on.

    images (3).jpeg
     
    #401 Tam, Apr 7, 2019
    Last edited: Apr 7, 2019
  2. AlyxMS
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    AlyxMS Junior Member
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    Why is part of Type 054A painted black? I’m not seeing the same thing on 052s.

    Why does the radar-panel-looking-thingy that hangs on top of 054A’s mast sit at an angle?
     
  3. gelgoog
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    gelgoog Senior Member
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    I suspect its some kind of fire or heat proof resistant paint. The engine exhaust is right below the black painted areas.
     
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  4. Tam
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    Tam Senior Member
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    Not easy to explain briefly why the radars must be angled. There is also the context of these types of radars and how they function, and in this case, the particular history of these radars. There are several points that need to be made.

    1. These radars electronically scan in the vertical for elevation, and is mechanically rotated for horizontal for azimuth or bearing information on the target. By using a serial time delay on the on each of the linear transmitters, the frequency shifts across the face and the interaction of these varying frequencies causes the beams to steer in a vertical pattern. This is why they are called Frequency Scan or FRESCAN radars. Radars that use this principle are commonly used as volume air search radars both on land and sea.

    2. Almost all of these radars are single faced and don't angle, with the notable exception of the Type 382 radar, which is not just used on the Type 054A, but also on the Liaoning and Carrier 002, with the carrier variants having a bit of a variation. The Type 382 in turn, copied this configuration from the Russian Top Plate radar, also known as Fregat, and these were imported with the Sovremenny destroyers, and ordered also for the Type 052B and Type 051C destroyers. The Type 381, which operates on the frequency scanning principle and is the predecessor to the Type 382, only has a single face and doesn't angle. This radar is featured on the Type 051B before the ship was refitted.

    Type_381_1.jpg

    a. The main difference between Type 382 and the Russian Fregat M2EM is that the Russian radar has an IFF array on top and the Type 382 has none. The carrier version of the Type 382 has a circular disk on top, reasons not clear. Another difference is that the Type 382 works is dual band, works on the S and C band, while the Fregat M2EM is only on the S-band. To accomplish this dual band, one face of the radar has to be on the S-band, which is the larger face, and the C-band is on the smaller face, which has smaller and finer elements.

    382-radar.jpg


    3. This is the Fregat M2EM. You can see the IFF bar on top. While the frequency scanning principle is common, and not invented by the Russians ---- you can trace this even earlier to US radars, like the SPS-48 used in US carriers --- the dual faced, with angled offset is unique to the Fregat. Hence why when this configuration appeared on the Type 382, the Russians have a good reason to complain about Chinese copying.





    One face is at 55 degrees and the other is at 45 degrees. The Russians have never fully explained the reason for that, but my guess is that the results between the two faces are compared to better precisely obtain both azimuth and elevation information on the target. If its really only about increasing update rate by going dual faces, the dual faces would be identical. The imposed differences between the two faces are deliberate for the purposes of signal comparison.

    4. Fregat/Top Plate is not the only Russian radars that are dual faced with each face being different. Take a look at the Top Steer and Top Sail radars, on the Slava and Kirov class cruisers. I think why the faces of one side and another are different is for signal comparison.


    MarshalUstinov1989radar.jpg
     
    #404 Tam, Apr 8, 2019
    Last edited: Apr 8, 2019
  5. Deino
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    Deino Brigadier
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    And with the Type 002 carrier close to hand-over, there seems to be something different in preparation at Dalian shipyard.
    Time to guess? ;)

    PLN Type 002 carrier + news maybe in empty dry dock at Dalian - 20190405 part+.jpg PLN Type 002 carrier + news maybe in empty dry dock at Dalian - 20190405.jpg
     
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  6. Deino
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    Deino Brigadier
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    Reminds a bit to this one ... start of construction of the 002 carrier in March 2015.
    But surely could be any other large vessel too.

    PLN Type 002 carrier at Dalian sat image 20150310.jpg
     
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  7. Tam
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    Tam Senior Member
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    I won't be surprised if they started building a fourth aircraft carrier there. But it can just be another large container ship.
     
  8. KIENCHIN
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    KIENCHIN Junior Member
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    Wasn’t there a rumour the second CATOBAR carrier would be build in Dalian? Hope this is it but then this could just be another container ship as you said.
     
  9. Interstellar
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    Interstellar Junior Member
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    The docking blocks have not been removed since the carrier undocked last time.
     
  10. Tetrach
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    Tetrach Junior Member
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    Hello it's me again. I'm wondering a few more questions;

    -Why does the Burke class embark a target illuminator for its missiles while the Type 52C/D doesn't ?

    -What is the actual objective of the type364 ?

    - What is the point of a rotary target illuminator radar as it won't be able to continuously track the enemy aircraft ?

    -How can a rotary radar "divide itself" if it is moving 40 rpm ?

    -The range of a radar is one thing, and how far it can effectively detect a potential target is an another concept. As such how can you optimise the effective range of a radar ? bigger front lobe? frequency ? etc

    A lot of (probably) stupid questions, I know. I'm just very interested in how radars work and I feel I will only learn but putting my thoughts and problems here !
     
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