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    Differences of AESA to PESA

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    SOC

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    Differences of AESA to PESA

    Post  SOC on Mon Jul 01, 2013 8:39 am

    Austin wrote:http://img137.imageshack.us/img137/6130/radary.jpg

    That's the image I was talking about mentioning it as an AESA.

    Austin wrote:Vityaz is most certainly PESA atleast on the pictures they showed , And the two planer antenna is I would suspect one for IFF and one for Height Finding.

    You usually don't need a separate height finder, those are typically reserved for EW functions to augment 2D surveillance radars (height being the missing D). You'd find subarrays on a PESA like this for things like sidelobe reduction, IFF functions, precision missile tracking, missile uplinks, etc.

    Austin wrote:I would suspect the need to mass produce Vityaz and a cost effective replacement for S-300P/PT would have made the decison go PESA way ,

    It's cheaper than an AESA, and they've proven they've got this technology mastered, so there's no reason to make it more complicated than mission requirements dictate.

    Austin wrote:Considering it already has ARH it better than S-300 missile and the PESA would also be of an advanced type.

    I'm not sure I'd say it's a completely "better" missile without all of the updated specifications, and ARH vs. SAGG is something we could debate at length.

    Austin wrote:SOC , How difficult it is to jam an AESA verus PESA radar using modern jammer , the thing I am aware of AESA is higher bandwidth and graceful degradation under jamming conditions , plus lower power needs.

    DRFM is always going to be a pain in the ass, at least in theory...unless you're doing fun things like messing about with your polarization, frequency hopping, etc. Lower power, however, isn't always a positive development. The original radar for the MiG-25P was very high power (could reportedly kill deer when activated on the ground), and that brute force enabled it to burn right through a lot of the jamming interference used at the time. Things are obviously different now, but in some cases more power is not a bad thing to have around. I'll give this some more thought in the morning and figure out what I can put here.
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    Morpheus Eberhardt

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    Re: Differences of AESA to PESA

    Post  Morpheus Eberhardt on Mon Jul 01, 2013 11:15 am

    SOC wrote:
    Morpheus Eberhardt wrote:A few points:

    - The existence of feedhorns for a space-fed array is indicative of the fact that the radar shown for this variant of Vityaz' is not an AESA (AFAR, АФАР), but it is not an indication that this radar is a PESA;  not all ESAs are either AESAs or PESAs.

    ?  AESA or PESA is basically referring to whether or not the T/R modules in the array face are either generating (AESA) or receiving from somewhere else (PESA) RF energy to transmit.  What sort of ESA wouldn't fall under one of those two categories?

    I gave an example in my earlier post on Irbis-Eh. To illustrate further, I will now elaborate a little bit on that earlier post.

    In a normal PESA, each antenna element has "only" a phase shift functionality. The reason for making a reference here to a "normal PESA" is that here I can't talk, in any detail, about ESAs like TTD-PESAs, for example.

    Irbis-Eh is semiactive (neither passive nor active) in transmit. It means that each antenna element of Irbis-Eh has, in addition to its phase shift functionality, a digitally gain-controlled amplification functionality. This capability provides for an optimized spatial gain profile to be generated by the array. This gain profile is a function of position on the plane of the array. In short, this means that the outcome of Irbis-Eh's TWT amplifier (with two ganged TWTs, by the way) feeding this kind of array would be indistinguishable from that of an AESA, i.e. same mainlobe, sidelobe and backlobe performance.

    As to the receive characteristics, Irbis-Eh is active on receive; that means it is identical to an AESA on receive.

    The Irbis-Eh case is just one example. There are many other kinds of ESAs, and most provide more capability than a run of-the-mill AESA. Some are more sophisticated variants of AESAs. Maybe I will have have some posts about them in the future.

    SOC wrote:
    Morpheus Eberhardt wrote:The apparent existence of a lower subarray (subarrays) can be an indication that the radar is actually a PESA, if that subarray was, for example, for purposes like generating nulls in the antenna pattern. The upper array is probably an L-band array which has IFF as one of its roles.

    It looks like there are possibly two subarrays above the main array face, stacked one atop the other.  To get a better impression of what's going on we need an image showing the back of the array face.

    I will address those maybe in some later post. The lacunae were deliberate, but I should have said "the array just to the top is probably ..."

    SOC wrote:
    Morpheus Eberhardt wrote:- The KM-SAM radar is a space-fed PESA.

    I've seen it mentioned in advertising materials as a "plain array active phase radar", possibly implying AESA.  However, the rotating antenna cabin does seem large enough to house a space-feed system behind the antenna, so who knows.

    Irrespective of the advertising material, it should probably be a space-fed PESA. Maybe the "developer" wasn't familiar with the design.

    Some telltale signs for my assertion are the shape of the antenna enclosure and also the four nulling subarrays. Universally these signs are not categorical, but in this situation they most probably are.

    Aside from that please see the internals of the antenna at the following links. The feed of similar design to that of the 30N6Eh type is visible, which indicates that the design is not an AESA.

    http://kjfaero.com/pr/pr04-03.htm
    http://kjfaero.com/pr/new/075.htm
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    sepheronx

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    Re: Differences of AESA to PESA

    Post  sepheronx on Mon Jul 01, 2013 3:02 pm

    Morpheus Eberhardt, I would so much look forward to when you do a document of some sort telling the differences of AESA to PESA, benifits vs not and various different methods inbetween (Hybrids).

    I know that this is not the first time I heard Irbis-E called a Hybrid, and I think I am understanding now why it is. Thank you for the info, and please, I would love to understand more so whenever you get the time.
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    SOC

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    Re: Differences of AESA to PESA

    Post  SOC on Tue Jul 02, 2013 2:22 am

    sepheronx wrote:I know that this is not the first time I heard Irbis-E called a Hybrid, and I think I am understanding now why it is.  

    It's a hybrid array because it's basically a PESA in transmit and an AESA in receive. It's not a full AESA because the individual receiver modules are not providing the signal (making them different from an AESA's transmit/receive modules), the signal comes from the separate power source via the TWTs and waveguides.

    Most of this is crap I haven't used for years. This week I'll dig out some of my radar design textbooks and come up with a better explanation of some of this mess if Morpheus hasn't gotten around to it by then.
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    Re: Differences of AESA to PESA

    Post  Morpheus Eberhardt on Tue Jul 02, 2013 9:32 am

    sepheronx wrote:Morpheus Eberhardt, I would so much look forward to when you do a document of some sort telling the differences of AESA to PESA, benifits vs not and various different methods inbetween (Hybrids).

    I know that this is not the first time I heard Irbis-E called a Hybrid, and I think I am understanding now why it is.  Thank you for the info, and please, I would love to understand more so whenever you get the time.

    sepheronx,

    Thanks. I'll do that; just that I have been a bit swamped with work recently.
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    Re: Differences of AESA to PESA

    Post  Morpheus Eberhardt on Tue Jul 02, 2013 9:41 am

    SOC wrote:
    sepheronx wrote:I know that this is not the first time I heard Irbis-E called a Hybrid, and I think I am understanding now why it is.  

    It's a hybrid array because it's basically a PESA in transmit and an AESA in receive.  It's not a full AESA because the individual receiver modules are not providing the signal (making them different from an AESA's transmit/receive modules), the signal comes from the separate power source via the TWTs and waveguides.

    Most of this is crap I haven't used for years.  This week I'll dig out some of my radar design textbooks and come up with a better explanation of some of this mess if Morpheus hasn't gotten around to it by then.

    SOC,

    That is not correct. Vide supra.
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    sepheronx

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    Re: Differences of AESA to PESA

    Post  sepheronx on Tue Jul 02, 2013 4:01 pm

    Morpheus Eberhardt wrote:
    sepheronx wrote:Morpheus Eberhardt, I would so much look forward to when you do a document of some sort telling the differences of AESA to PESA, benifits vs not and various different methods inbetween (Hybrids).

    I know that this is not the first time I heard Irbis-E called a Hybrid, and I think I am understanding now why it is.  Thank you for the info, and please, I would love to understand more so whenever you get the time.

    sepheronx,

    Thanks. I'll do that; just that I have been a bit swamped with work recently.

    I understand. I look forward to it and wish you best in your current work (hope things go smooth). respekt 

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    Re: Differences of AESA to PESA

    Post  Rpg type 7v on Tue Jul 02, 2013 6:26 pm

    SOC wrote:
    sepheronx wrote:I know that this is not the first time I heard Irbis-E called a Hybrid, and I think I am understanding now why it is.  

    It's a hybrid array because it's basically a PESA in transmit and an AESA in receive.  It's not a full AESA because the individual receiver modules are not providing the signal (making them different from an AESA's transmit/receive modules), the signal comes from the separate power source via the TWTs and waveguides.

    Most of this is crap I haven't used for years.  This week I'll dig out some of my radar design textbooks and come up with a better explanation of some of this mess if Morpheus hasn't gotten around to it by then.
    That only improves sensitivity (separate receiver), the all main advantages of Aesa radar types over Pesa , lye in the emmiting part of it (emission part).
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    medo

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    Re: Differences of AESA to PESA

    Post  medo on Wed Jul 03, 2013 5:06 pm

    I don't have experience with neither PESA neither AESA radar, but as I know, PESA radar is also capable of frequency hoping as well as electronically control transmitting pulse in miliseconds and send them with low energy in different places for very short time, to be more difficult to detect, specially for older RWRs, so those moduls still control transmitting signals although not transmit themselves. Maybe PESA is better for engagement radar, because one larger transmitter could easier focus high power in one point than 1000 smaller ones, what is quite important for missile guiding and to overcome jamming signal.

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    Re: Differences of AESA to PESA

    Post  Rpg type 7v on Wed Jul 03, 2013 8:13 pm

    there is a loss when a feed signal goes trough phase shifters in the antennae ,newer aesa also is better at focusing and can work at 110% for a short time Wink 
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    Re: Differences of AESA to PESA

    Post  medo on Wed Jul 03, 2013 9:06 pm

    I think in that case AESA need good cooling system around T/R modules to not overheat. Maybe PESA have here for now advantage, because transmitter is outside and could keep high power for longer time. But with time cooling will become better and AESA more standard for Russian military. At the moment they have only early warning AESA radars, because they don't need that high power as engagement radars.

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    Re: Differences of AESA to PESA

    Post  Rpg type 7v on Wed Jul 03, 2013 9:17 pm

    not just cooling. its about efficiency .,how much energy is turned into radiation ,and how much to waste (mostly heat)...i had a good picture but cant find it now...cry 
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    Re: Differences of AESA to PESA

    Post  medo on Wed Jul 03, 2013 9:29 pm

    That goes one with another. If you could not effectively cool it, efficiency drop and the system go out. AESA need less power to send a signal of 1W per square meter than PESA, but to increase power of signal you need more cooling for T/R moduls to not overheat, while in PESA transmitter is outside and with that easier to cool down receiving modules.

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    Re: Differences of AESA to PESA

    Post  Rpg type 7v on Wed Jul 03, 2013 10:35 pm

    ok found it (finally:lol: )


    now for modified pesa the receiver cutoff is before the waveguide so noise is half d.

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    Re: Differences of AESA to PESA

    Post  Mindstorm on Thu Jul 04, 2013 3:29 pm

    Rpg type 7v wrote:ok found it (finally:lol: )


    now for modified pesa the receiver cutoff is before the waveguide so noise is half d.


    From what publication has been taken this over-simplistic image ?

     (moreover those signal noise figures and PESA radar layout's design appear very outdated even for 15-20 old specimens !!)


    I know that , for some reason, has been widely spread and is ,by now, deeply rooted this odd linking in a biunivocal relation  "low probability to intercept" to AESA radars ; the problem is that it is simply not so Smile 


    Wide majority of radars, ground ship or airborne based, classified as "LPI"  -the main characterizing features of which are : effective bandwidth, seriability of scan patterns, side lobes size and magnitudo, radiated power management, frequency agility and pulse's compression/modulation/encoding and ambiguity's index -   and now operatives worldwide are not-AESA radars.  (some "western" samples of that are Raytheon AN-APQ-181 and AN/APG70, Raytheon MRSR ,Telephonics AN/APS-147,  ELTA EL/M-214039 etc..etc...)

    If we exclude a certain increase in beam shape's modulation rate ( somewhat degrading the mean time of modulation period's extraction for the opposing RWR ) and radiated power control for the effect of the possibility to arrange the amplitude and phase of single T/R elements ,  the LPI capabilities of an AESA and a modern PESA radar are almost unnoticeable.


    Exist even instances (mostly where sidelobe performances and/or raw signal-to-noise ratio are the central requirements) where even a mechanically steered coherent pulse radar is preferred ,under a strict technical point of view, over an AESA.  (like in the Telephonics AN/APS-147 instance).
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    Re: Differences of AESA to PESA

    Post  medo on Thu Jul 04, 2013 5:01 pm

    Rpg type 7v wrote:ok found it (finally:lol: )


    now for modified pesa the receiver cutoff is before the waveguide so noise is half d.

    PESA module obviously have more elements inside than AESA module. More elements could also mean more protection for receiver and those losses could be also translated in heat exchange (longer chain means longer time of cooling). Of course every radar have its own construction and its own scheme of elements in its chain. It seems PESA have better cooling capabilities and with that better capabilities to work with high power signals and with that jamming resistance.

    I would like to ask a question to those, who have experiences with ESA type radars. I personally have a situation on exercises, where jamming signal turn off my whole system. OK radar was classical mechanical one and jammer was ground base, which is of course more powerful than any airborn jammer and quite close to my position. Although I didn't have transmitting on, jamming signal was so strong, that it turn off whole system and I have to turn it on again. Is it possible, that similar high power jammer or high power PESA radar could focus enough strong signal into AESA element to turn them off? Considering, that AESA T/R modules also transmit in the same time, is it possible to overheat them with strong focused signal in it?

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    Re: Differences of AESA to PESA

    Post  Rpg type 7v on Thu Jul 04, 2013 7:03 pm

    Mindstorm wrote:
    Rpg type 7v wrote:ok found it (finally:lol: )


    now for modified pesa the receiver cutoff is before the waveguide so noise is half d.


    From what publication has been taken this over-simplistic image ?
    (moreover those signal noise figures and PESA radar layout's design appear very outdated even for 15-20 old specimens !!)


    study from a book of 600 pages....tongue 

    ok ,cant wait to see your diagram example jocolor Rolling Eyes 
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    SOC

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    Re: Differences of AESA to PESA

    Post  SOC on Thu Jul 04, 2013 11:18 pm

    Mindstorm wrote:From what publication has been taken this over-simplistic image ?

     (moreover those signal noise figures and PESA radar layout's design appear very outdated even for 15-20 old specimens !!)

    It's from George Stimson's Introduction to Airborne Radar. And yes, the text is very outdated, being last updated in 1998, which explains some of the discrepancies. ESA's are only covered in a small section at the back of the book, it's primary purpose is to provide an intro to the mathematics and physics behind airborne radar systems (i.e. how the signal itself is generated, how it all works, how the system interprets targets, etc). From that perspective it remains a very useful volume, you just have to accept that some of the design bits at the end are obviously outdated. It's basically "radar for dummies", provided said dummies have a good math background; the pre-update text was originally an in-house textbook for Hughes radar engineers.

    For something more recent (2004) and more amusing, I'd recommend David Lynch's Introduction to RF Stealth, dealing primarily with the design of radars and system architecture for LO platforms.

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    Re: Differences of AESA to PESA

    Post  Mindstorm on Thu Jul 04, 2013 11:18 pm

    Rpg type 7v wrote:
    Mindstorm wrote:
    Rpg type 7v wrote:ok found it (finally:lol: )


    now for modified pesa the receiver cutoff is before the waveguide so noise is half d.


    From what publication has been taken this over-simplistic image ?
    (moreover those signal noise figures and PESA radar layout's design appear very outdated even for 15-20 old specimens !!)


    study from a book of 600 pages....tongue 

    ok ,cant wait to see your diagram example jocolor Rolling Eyes 





    from a book of 600 pages....


    And what this should mean ?

    You are even more naive than what i had belived.....


    Rpf type 7v i know that you love your (if you allow me to say very very convoluted) "troll work" here ,but now is sufficient a name of the book in question and a date of publication to qualify the level of the attempt.....do you know someone could already know the responses to those questions and theirs meaning.

    Not that i was surprised : after all you are the same guy attempting to compulsively "troll" on Pantsyr-S1's performances attempting a......very unlucky comparison with BAMSE Laughing , or getting the courage to cite Meteor AAM as example of foreign technological product in a......Russian forum ( Prof. V. Sosounov and M. Tskhovrebov of CIAM and V. Rosenband of Semenov Institute could say to you a thing or two on the deciding role of domestic achievements in the SFRJ propulsion and boron particulate combustion, sold to Onera and Roxel, in the development of Meteor AAM Very Happy ).




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    Re: Differences of AESA to PESA

    Post  Rpg type 7v on Thu Jul 04, 2013 11:23 pm

    this works for every radar ,or there exists pesa without phaseshifters and receiver protectors - like i said i cant wait for your modern diagrams. youre da troll.

    as for solid fuel ramjet i have to say kub missile development 3m9 ,,proved very troublesome 9 years Laughing , and the russians gave up on it in second generation of AA missiles -buk -solid rocket.
    as for french they had asmp for looong time....

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    Re: Differences of AESA to PESA

    Post  Mindstorm on Thu Jul 04, 2013 11:32 pm

    For something more recent (2004) and more amusing, I'd recommend David Lynch's Introduction to RF Stealth, dealing primarily with the design of radars and system architecture for LO platforms.

    SOC if we want to remain in the english language why not ,then, the second edition of "Detecting and Classifying Low Probability of Intercept Radar" by Phillip E. Pace of 2009 , moreover with one of the best section on radar pulse encoding and decoding techniques of any western open publications ?
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    SOC

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    Re: Differences of AESA to PESA

    Post  SOC on Thu Jul 04, 2013 11:54 pm

    Mindstorm wrote:
    For something more recent (2004) and more amusing, I'd recommend David Lynch's Introduction to RF Stealth, dealing primarily with the design of radars and system architecture for LO platforms.

    SOC if we want to remain in the english language why not ,then, the second edition of "Detecting and Classifying Low Probability of Intercept Radar" by Phillip E. Pace of 2009 , moreover with one of the best section on radar pulse encoding and decoding techniques of any western open publications ?

    Because I don't have that one, so I wouldn't have thought of the title jocolor 

    Something else for me to pick up though, along with this one: http://www.scitechpub.com/catalog/product_info.php?products_id=344
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    Re: Differences of AESA to PESA

    Post  NickM on Fri Jul 05, 2013 11:36 am

    SOC wrote:Because I don't have that one, so I wouldn't have thought of the title jocolor 
    The best course material on any hardware / software related to Defense & Aerospace are published by Cranfield University .

    http://www.cranfield.ac.uk/cds/postgraduatestudy/guidedweaponsys/page16167.html

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    Re: Differences of AESA to PESA

    Post  Rpg type 7v on Sat Jul 06, 2013 6:18 pm

    lol nothing as i expected...
    the guy asked for some basic pesa vs aesa differences,and i answered in that manner, not advanced ecm, eccm ,radar modes etc.
    whatever...
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    Vityaz radar

    Post  GarryB on Sun Jul 07, 2013 11:53 am

    as for solid fuel ramjet i have to say kub missile development 3m9 ,,proved very troublesome 9 years Laughing , and the russians gave up on it in second generation of AA missiles -buk -solid rocket.
    as for french they had asmp for looong time....

    They switched from ramjet to solid fuel in the SA-6 to SA-11/17 because solid rocket fuel performance had increased rather more than ramjet efficiency had.

    Now however it is scramjets that offer potential rather greater than any type of solid or liquid or gel propellent... the Kh-31 continues to use ramjet and expect there to be scramjets to replace them in ARMs, AShMs and even AAMs and SAMs.


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