Pakistan's Airborne Early Warning and Control Aircrafts

[Safriz]

 

[karan21]

Can anyone tell me capabilities of Pakistan in radar development and what efforts are being made in Aesa and synthetic aperture radars??

 

[gambit]

Basically the AESA array in the ZDK radar can only scan in the vertical .... so the dish is rotated mechanically to provide 360 coverage.

Is that a disadvantage or more of a dicomfort ? As in what would be the opportunity cost of not having a dish that is rotated otherwise when compared with having one which is rotated mechanically ?

Visualization is helpful...

The left illustration is the typical AWACS antenna shape with resulting beam shape.

Antenna shape dictate beam shape and the more deviation from circular, the more deviation the beam from the typical cone shape, and the fan shaped beam is always 90deg from antenna orientation. The right illustration is usually for ground air traffic control where the antenna simply 'nod' up/down. As the fan beam sweeps in that up/down motion, each movement corresponds to an altitude gradient, and that helps air traffic controllers distinguish individual flyers at different altitudes.

So for an AWACS (left), the 'saucer' shaped dome that houses the antenna must be rotated horizontally for the vertically oriented fan beam to provide 360 deg coverage. Even when the antenna is not transmitting, the dome should still be rotating a little bit to keep the entire contraption continuously lubricated.

That is what a typical 'cone' shaped beam looks like on a 3D graph. You can see the main cone where target info are actually processed. The side 'petals' are side lobes and undesirable. Many electronic warfare (EW) tactics targets the side lobes for confusing the system with distraction and false target data. The goal is to reduce, but never completely eliminate, side lobes in any design. ESA systems have much lower quantity of side lobes and whatever there are, those side lobes are much lower in intensity (distance from antenna) and far less vulnerable to ECM tactics.

So for an AWACS all you have to do is imagine flattening the main lobe into fan shape and really elongate the side lobes. An AWACS beam looks really weird on a 3D graph.

 

[Armstrong]

A noob question : How many AWACs do we need to provide complete coverage of Pakistan & enough coverage of the adjoining areas to respond preemptively in case of any misadventure against us ?

 

[Armstrong]

@ Gambit : Thanks for that, I appreciate it ! Please bear with me because I don't really know the first thing about these things & yet I'm interested to find out : Can the radar dome be constructed of such a configuration that it has two separate parts moving independently - One scanning the horizontal plane whilst the other scanning the Vertical plane & that their results are transmitted as such to the controller sitting inside the platform that he/she has at his/her disposal a truly 3-D image of the surroundings as far as the radar's coverage/range would permit it ?

 

[gambit]

A noob question : How many AWACs do we need to provide complete coverage of Pakistan & enough coverage of the adjoining areas to respond preemptively in case of any misadventure against us ?

Never enough. That is a serious answer. Keep in mind that the aircraft is mobile so as it move you will need another to provide coverage where it used to be. And so on and so on. You will need to keep the aircraft on a constant altitude, heading, and airspeed so the entire system can provide continuous coverage of the entire border system because each aircraft will need to know the coverage range and area of the previous aircraft and on and on...So financially speaking, you will not have enough coverage.

Now, if you are tiny like Luxembourge...

 

[Armstrong]

Never enough. That is a serious answer. Keep in mind that the aircraft is mobile so as it move you will need another to provide coverage where it used to be. And so on and so on. You will need to keep the aircraft on a constant altitude, heading, and airspeed so the entire system can provide continuous coverage of the entire border system because each aircraft will need to know the coverage range and area of the previous aircraft and on and on...So financially speaking, you will not have enough coverage.

Now, if you are tiny like Luxembourge...

So there really isn't a substitute for a good ground radar cover..is there ?

 

[Armstrong]

Okay people just one last noob question, lest I overstep my welcome (if I haven't already) : If a platform the likes of a decent sized propeller driven plane is enough to carry a radar & electronics suites to provide this much coverage why aren't there dedicated Radar Ships the size of a FAC (I'm thinking 100-500 tonnes) which are purely designed to provide radar coverage well upto a few hundred kms away with them operating just off the coast (I'm thinking a 100 or so Kms) ?

And Gambit, thanks man I really do appreciate the illustration & you taking out the time to answer that might come as sort of stupid at best & outright moronic at the very worst, to one who knows about these things !

 

[gambit]

@ Gambit : Thanks for that, I appreciate it ! Please bear with me because I don't really know the first thing about these things & yet I'm interested to find out : Can the radar dome be constructed of such a configuration that it has two separate parts moving independently - One scanning the horizontal plane whilst the other scanning the Vertical plane & that their results are transmitted as such to the controller sitting inside the platform that he/she has at his/her disposal a truly 3-D image of the surroundings as far as the radar's coverage/range would permit it ?

No, because aerodynamic consideration trumps all demands. That is why an ESA system is so desirable. With an ESA system, you can do 'sub-array partitioning', like how computer geeks partition a physical hard drive into many logical hard drives.

For example...

Digital Array Radar Panel Development | EEWeb

A 16-element, S-band subarray has been developed with panel-integrated, plastic-packaged high power amplifiers, multi-channel transceiver ICs, and digitization at the element level.

Sub-array partitioning and choreography software are complex and bad coding can produce many false targets.

From the above, only (a) is unitary while the other three have been partitioned into many sub-arrays for different purposes -- AT THE SAME TIME.. An AESA system is the only true real time multi-tasker. Everything else is just faking it. So you can have one sub-array to produce a fan beam for volume search and another sub-array to produce a tight 'pencil beam' for high precision target tracking.

And if your coding is bad, then you are in a world of trouble.

 

[gambit]

So there really isn't a substitute for a good ground radar cover..is there ?

No. To provide continuous border coverage, ground stations are best, and that includes high elevation stations as well, such as on hill tops.

Okay people just one last noob question, lest I overstep my welcome (if I haven't already) : If a platform the likes of a decent sized propeller driven plane is enough to carry a radar & electronics suites to provide this much coverage why aren't there dedicated Radar Ships the size of a FAC (I'm thinking 100-500 tonnes) which are purely designed to provide radar coverage well upto a few hundred kms away with them operating just off the coast (I'm thinking a 100 or so Kms) ?

You will have to hit up the Ministry of Finance on that one.

 

[Bratva]

these posts are treat to watch whenver ZDK is being discussed!

Thats not the ONLY reason, another reason is that a larger array can be placed in a rotating dome giving more range, while placing triangular dome reduces the size of each array by ~20%.

A simple trignometric analysis shows that the maximum array size of triangular dome (like KJ2000 and Phalcon) is 20% less than a straight radial array along its diameter (like E-3-Sentry, E-2D-Hawkeye, ZDK03).

Moreover, previously the pulse doppler version of rotating domes gave a 20sec radar darkness over any perticular point due to the fact that they could only illuminate targets in direct line of sight in perpendicular to the array, but the AESA doesnot have that restriction. Instead AESA can electronically steer a radar beam to illuminate 60 degrees to either side of perpendicular. This covers 120 degree to each side totalling 240 degrees of instantaneous view, while leaving 60 degree on each corner in radar darkness. When rotating at same speed of 40 sec per rotation, same as with pulse dopler version, it will illuminate a full 360 degree circle in 6 seconds. Thus a target is re-illuminated 6 seconds after it goes into dark region. Also this is assuming ZDK-03 has AESA with 120 degree field of view, which is only an assumption. In actuality it might have 150 degree field of view AESA (like Erieye atop Saab2000) which will reduce re-acquisition time to 3 sec.

One more thing to note is that fixed dome suffers from constant side lobe attenuations in regions deviating close its electronic steering boundary, for extended periods of time; while giving good target data at regions close to perpendicular. On the other hand, rotating dome ensures maximum search precision for all 360 degrees within a maximum of 10 seconds, and that too without changing the heading of the platform itself.

If you ask me, having 20% plus range is much much more desirable than 3 seconds of radar darkness, besides being cost effective as well.

Regards,
Sapper

Now my first assumption is that two complimenting AESAs are placed inside the rotating dome, i.e. the similar kind of double sided Erieye configuration, but in rotating configuration. This is based on the assumption that
1. Dual sided aesa was already available with china on Y-8 platform at similar cost, but not opted for by PAF,
2. AESA is comparatively thin and does not require additional wasted space for dedicated transmitter assembly on the backside, since every single unit is itself a transmitter reciever on its own.
3. China already posses the technology to fit 3xAESA in a radome and 2xAESA in sandwitch-BalanceBeam configurations, placing the balance beam config would have been no problem to place into a rotating radome.

If thats the case for ZDK-03 (unless proven on the contrary) I will proceed with the following calculations.


Assume 40 sec per rotation, which is normal, and 120 arch illumination (60 deg from perpedicular) for AESA array, which is also normal.
360 deg per 40 sec = 9 deg per sec (RotationSpeed)

Assume a target is at 0-deg, Radar starts spinning, at radar's-0-deg, target is fully perpedicular and perfectly lit
Radar goes to 45-deg, still lit.
Radar goes 60-deg, still lit.
Radar goes 61-deg, target lost.
Now radar goes 90-deg, target is still lost.
Radar goes 119-deg, still lost.
Now radar comes to 120 deg, still lost for the array pointing 120, but the array facing exactly opposite to it i.e. at 120+180 deg = 300-deg has illumination till 360 deg, which is the same as 0-deg, target lit by opposing array, target acquired.

Now target lost at 61-deg ... and reacquired at 120-deg.
Lost-Time = 60-deg / RotationSpeed = 60 / 9 = 6.6 sec


I may be wrong, and ZDK-03 might only have a single AESA pointing to one side, as in legacy E3Sentry, in which case the re-acquisition will take 26 seconds to re-acquire target, but lets wait for the time when PAF or China releases specs. If thats the case apologies in advance.

Regards,
Sapper

 

[Donatello]

these posts are treat to watch whenver ZDK is being discussed!

Where is Sapper? Someone really needs to find him and drag him to post here on PDF. We really need his know how.

 

[farhan_9909]

can someone tell me how will Erieye and ZDK-03 communicate with each other when there is no SATCOM on any of them?

how will a F-16 be connected with Erieye?

has the F-16 link up completed with erieye?

or JFT with ZDK-03?

 

[fatman17]

The question about the stricken erieye remains unanswered..
So we dont know how many erieye PAF are left with...

its answered. you dont want to believe it.

 

[Jango]

The question about the stricken erieye remains unanswered..
So we dont know how many erieye PAF are left with...

Ab main bolun ga to acha nhn lagay ga, so I'll keep quite.

And in post 3043, it is 09049, not 10049.