max range of the an/apg81 and AESA

Unread postPosted: 03 Mar 2016, 00:42
by shab249
I know for the 77 its 400 meters for 1m2 but i not finding about the 81 and can someone explain me what is a AESA radar sorry for thr stupid question and how it compares with 4th gen radars

Re: max range of the an/apg81 and AESA

Unread postPosted: 03 Mar 2016, 00:47
by spazsinbad
'shab249' said: "...can someone explain me what is a AESA radar sorry for thr stupid question..."

You might try searching/reading posts on this forum, or even the internet, about what interests you about the F-35. This is the age of 'self education', or at least a bit, try 'educated questions'. Try that for a 'stupid answer' to a 'stupid question'?

Re: max range of the an/apg81 and AESA

Unread postPosted: 03 Mar 2016, 00:59
by coldman
spazsinbad wrote:
'shab249' said: "...can someone explain me what is a AESA radar sorry for thr stupid question..."

You might try searching/reading posts on this forum, or even the internet, about what interests you about the F-35. This is the age of 'self education', or at least a bit, try 'educated questions'. Try that for a 'stupid answer' to a 'stupid question'?

Remember kids, google is your friend.

Re: max range of the an/apg81 and AESA

Unread postPosted: 03 Mar 2016, 01:17
by shab249
coldman wrote:
spazsinbad wrote:
'shab249' said: "...can someone explain me what is a AESA radar sorry for thr stupid question..."

You might try searching/reading posts on this forum, or even the internet, about what interests you about the F-35. This is the age of 'self education', or at least a bit, try 'educated questions'. Try that for a 'stupid answer' to a 'stupid question'?

Remember kids, google is your friend.

spazsinbad wrote:
'shab249' said: "...can someone explain me what is a AESA radar sorry for thr stupid question..."

You might try searching/reading posts on this forum, or even the internet, about what interests you about the F-35. This is the age of 'self education', or at least a bit, try 'educated questions'. Try that for a 'stupid answer' to a 'stupid question'?

All i know about jets i searched myself from places like Wikipedia and i didnt get what is aesa radarr its on fancy words on Wikipedia so next time someone asks here question just answer if its not so painful for you guys...

Re: max range of the an/apg81 and AESA

Unread postPosted: 03 Mar 2016, 01:25
by KamenRiderBlade
First solution is to keep on digging in Wikipedia until you can understand Wikipedia level terminology.

If Wikipedia can't explain a certain term, then google the term.

Re: max range of the an/apg81 and AESA

Unread postPosted: 03 Mar 2016, 01:46
by Dragon029
Here's a rough intro to AESAs (in the context of fighters):

There's 3 main types of radar today (in aircraft), Mechanically Scanned Arrays (MSA), Passive Electronically Scanned Arrays (PESA) and Active Electronically Scanned Arrays (AESA).

Traditional radars, which were MSAs, had a dish and you scanned the sky by swivelling that radar left and right, up and down, while you shoot out pulses of energy and wait for a return signal. If you got a weak signal, you could swivel in a smaller area and hunt for where you got the strongest signal. That gave you the direction of the enemy.

With PESAs and AESAs, there's a flat face with hundreds of antennas sticking out. Each antenna is also like a speaker; if you tune the timing of each speaker (antenna), you can cause the sound waves (radar pulses) to interfere with each other and be amplified in a certain direction. Using this technique, PESAs and AESAs can fire very thin, powerful beams of radar energy at a target. However, they are limited to a field of view of 120 degrees (60 degrees left / right / up / down) unless you also make the radar physically gimbal (a no-go for stealth aircraft).

The difference between a PESA and AESA is that whereas in a PESA, you have 1 powerful signal generator that then pipes it's radar energy (microwaves) out to all of the antennas where a device tweaks the signal to allow for the aiming aiming of the radar pulse, AESAs have a signal generator on every antenna. The more antennas (also known as Transmit / Receive (T/R) modules on AESAs), the more powerful an AESA is.

AESAs are overall the most advanced type of radar and most capable. PESAs are good as well, but they get a lot of internal interference (noise) in the piping between the signal generator and the antennas, which reduces their gain (signal strength). PESAs can also only operate one on frequency at a time, meaning that they can't do certain fancy tricks that AESAs can, like splitting the radar into multiple smaller / weaker radars and broadcasting on a wide range of frequencies simultaneously (reducing the probability of enemy radar / radar warning receivers detecting the AESA's signal - they'll be more inclined to think it's just random background noise).

Re: max range of the an/apg81 and AESA

Unread postPosted: 03 Mar 2016, 06:58
by blindpilot
shab249 wrote:
Dragon029 wrote:Here's a rough intro to AESAs (in the context of fighters):

There's 3 main types of radar today (in aircraft), Mechanically Scanned Arrays (MSA), Passive Electronically Scanned Arrays (PESA) and Active Electronically Scanned Arrays (AESA).

Traditional radars, which were MSAs, had a dish and you scanned the sky by swivelling that radar left and right, up and down, while you shoot out pulses of energy and wait for a return signal. If you got a weak signal, you could swivel in a smaller area and hunt for where you got the strongest signal. That gave you the direction of the enemy.

With PESAs and AESAs, there's a flat face with hundreds of antennas sticking out. Each antenna is also like a speaker; if you tune the timing of each speaker (antenna), you can cause the sound waves (radar pulses) to interfere with each other and be amplified in a certain direction. Using this technique, PESAs and AESAs can fire very thin, powerful beams of radar energy at a target. However, they are limited to a field of view of 120 degrees (60 degrees left / right / up / down) unless you also make the radar physically gimbal (a no-go for stealth aircraft).

The difference between a PESA and AESA is that whereas in a PESA, you have 1 powerful signal generator that then pipes it's radar energy (microwaves) out to all of the antennas where a device tweaks the signal to allow for the aiming aiming of the radar pulse, AESAs have a signal generator on every antenna. The more antennas (also known as Transmit / Receive (T/R) modules on AESAs), the more powerful an AESA is.

AESAs are overall the most advanced type of radar and most capable. PESAs are good as well, but they get a lot of internal interference (noise) in the piping between the signal generator and the antennas, which reduces their gain (signal strength). PESAs can also only operate one on frequency at a time, meaning that they can't do certain fancy tricks that AESAs can, like splitting the radar into multiple smaller / weaker radars and broadcasting on a wide range of frequencies simultaneously (reducing the probability of enemy radar / radar warning receivers detecting the AESA's signal - they'll be more inclined to think it's just random background noise).


Thanks now i know :)


I would only add one context perspective that is implied above. There is "knowing" and then there is understanding what that truly means in operations.

As noted AESA is both very frequency and beam agile. That can manifest itself as seeming to have many older type radars operating from the same footprint (nose space) and load (weight/power) doing many functions simultaneously in a given time window. That provides a large selection of those functions all happening at the same time (practically speaking) - ground/surface mapping/targeting,while air to air track/targeting, while jamming, with Low Probability of intercept(LPI) emissions... and perhaps while communicating all that info, also LPI, to the rest of the strike package, airborne, afloat and on land, and controlling weapons that those elements launched.

That type of mission power is more than simple specs on range etc. It opens a whole new world of mission operations, that fifth gen operators are just beginning to explore. The potential "mission power" could be orders of magnitude higher than other types.

New design approaches are not simply "40% better detection" or "twice the power and range" or "tracks three times more targets at a time" Often they completely upset the apple cart, totally changing "how things are done" for a mission. Modern AESA radars with increased computing power and new software fall into that category.

FWIW,
BP

Re: max range of the an/apg81 and AESA

Unread postPosted: 03 Mar 2016, 07:34
by spazsinbad
APG-81 AESA Radar for the F-35 JSF
Uploaded on Aug 31, 2009 Northrop Grumman

"The AN/APG-81 radar is designed to enable F-35 pilots to effectively engage air and ground targets at long range, while also providing outstanding situational awareness."


Re: max range of the an/apg81 and AESA

Unread postPosted: 03 Mar 2016, 12:40
by hornetfinn
Dragon029 wrote:Here's a rough intro to AESAs (in the context of fighters):


That was an excellent summary of the different radar technologies in simple terms!

AESA has also the advantage of having much wider total bandwidth (frequency range) where it can operate. This makes them much more difficult to detect and much more resistant to electronic warfare. It also gives the advantage of giving much better resolution which is especially improtant in radar mapping and identification modes (like SAR/ISAR).

Another thing is that they are much more reliable and robust systems than either PESA or MSA radars by about an order of magnitude better. Makes them fail less and also require less maintenance.

One imporant thing is also the far superior adaptivity of AESA over other technologies. Basically the software and control hardware are the only limits for AESA technology. They can be used for ESM (listen to enemy RF signals), EW (jamming) and high speed communications besides being used as radars.

Basically AESA is the best technology for radar system and has by far the most growth potential in the future.

Re: max range of the an/apg81 and AESA

Unread postPosted: 03 Mar 2016, 12:57
by optimist
my pleb understanding to get my head around it some how is to relay it back to stuff I can understand

If you substitute Spread Spectrum with Radar on this page, I think you will be very close
http://www.sss-mag.com/ss.html#tutorial
a bit more to read
https://www.google.com.au/#q=%22spread+ ... crowave%22

your cell phone system can be thought of as a radar and stuff, in what can be done too. out of all the 1,000's of calls that would be just noise if you heard it all at once..comes a very clear return signal from what you sent. It can position you and tell you where your caller is and lots of other stuff. there is also google, apps and instant messaging. lets not forget google earth

Re: max range of the an/apg81 and AESA

Unread postPosted: 30 Sep 2016, 22:14
by spazsinbad
I guess GaN will find a way into the F-35? OR it will not be suitable? I have no idea. NOT mentioned in this article:

http://breakingdefense.com/2016/09/plan ... m-nitride/ 29 Sep 2016

Re: max range of the an/apg81 and AESA

Unread postPosted: 01 Oct 2016, 02:12
by Dragon029
GaN will almost certainly make its way into the F-35 (unless an even better tech comes out / becomes mass produceable in the next decade or so). Increased output power may not seem ideal for a stealth aircraft, but it'll help with self-defensive EW and stand-off EW, and it might also allow the F-35 to boost the range of its MADL even further.

Re: max range of the an/apg81 and AESA

Unread postPosted: 01 Oct 2016, 02:33
by SpudmanWP
There is an possible benefit of GaN for the AESA radars of both the F-22, F-35, or any other AESA radar.

The reduced requirement of T&R modules in order to maintain the same radiating power means that the dish itself can be moved farther up into the nose. This allows the creation of "cheek" arrays on the sides of this new dish mount without having to do any changes to the body of the fighter.

Re: max range of the an/apg81 and AESA

Unread postPosted: 01 Oct 2016, 02:45
by spazsinbad
Thanks for the clues - sounds interesting.

Re: max range of the an/apg81 and AESA

Unread postPosted: 01 Oct 2016, 07:34
by vanshilar
Hmm -- I thought the F-35's nose was sealed because they didn't need to service the radar for the lifetime of the individual article? If so, would they have to cut open the nose to install a GaN radar?

Re: max range of the an/apg81 and AESA

Unread postPosted: 01 Oct 2016, 07:59
by SpudmanWP
It's sealed in that they never "need' to remove the RAM seals. They can still do upgrades.

When the radar T&R modules get upgraded, it will happen at a depot that can do a much better job of sealing up the nose than a field tech can.

Re: max range of the an/apg81 and AESA

Unread postPosted: 01 Oct 2016, 08:44
by optimist
It doesn't open for array servicing, but if they got it in there, they can get it out. Even if the seat comes out first and work from that end. There would be a way in case of complete failure.

Re: max range of the an/apg81 and AESA

Unread postPosted: 01 Oct 2016, 15:27
by eloise
hornetfinn wrote:AESA has also the advantage of having much wider total bandwidth (frequency range) where it can operate. This makes them much more difficult to detect and much more resistant to electronic warfare. It also gives the advantage of giving much better resolution which is especially improtant in radar mapping and identification modes (like SAR/ISAR).

Why wide bandwidth give better SAR resolution?
Please correct me if iam wrong but Isn't resolution of unfocused SAR limited by this :
Image
and resolution of focused SAR is limited by this :
Image

Image

Re: max range of the an/apg81 and AESA

Unread postPosted: 01 Oct 2016, 16:10
by bring_it_on
Industry is simply waiting for AMDR-X to take GaN T/R module cost down to acceptable levels and we should see both Raytheon and Northrop Grumman offer something that upgrades the current generation of AESA's. The current JSTARS-Recap sensor could also shed some light. Raytheon has quite publicly said that it will be competing with GaN for all AESA's going forward and given that NG enjoys some advantage due to being an incumbent they may see fit to offer a GaN sensor and with them NG will most likely also offer something like that.

Re: max range of the an/apg81 and AESA

Unread postPosted: 01 Oct 2016, 21:45
by popcorn
Not to forget NGJ will employ GaN-based AESA.

Re: max range of the an/apg81 and AESA

Unread postPosted: 01 Oct 2016, 23:54
by bring_it_on
The current GaN programs completely funded by the services or industry -

- AMDR-S band (Navy)
- LRDR-S band (USAF)
- G/ATOR-S band (USMC)
- NGJ-Mid (USN)
- EPAWSS (USAF)
- AN/TPS-77s - DART - L (Export - to be delivered end of year or early next year)
- Space Fence - S
- TPY-X - L band ( under testing at Lockheed)
- TPY-2 - X band (upgraded radar contracted for in FY16)
- Raytheon Lower Tier sensor ( C band, internal testing with Raytheon)
- Lockheed Lower Tier Sensor ( S or X band under development)

3DELRR had down-selected Raytheon's C band GaN sensor but they will be going back and making a down-select again next year. All three sensors for that program use GaN.

Higher frequency components would probably be quite expensive until TPY-2 (export to Qatar and UAE) come through and AMDR-X brings in volume demand.

Re: max range of the an/apg81 and AESA

Unread postPosted: 03 Oct 2016, 12:42
by hornetfinn
eloise wrote:
hornetfinn wrote:AESA has also the advantage of having much wider total bandwidth (frequency range) where it can operate. This makes them much more difficult to detect and much more resistant to electronic warfare. It also gives the advantage of giving much better resolution which is especially improtant in radar mapping and identification modes (like SAR/ISAR).

Why wide bandwidth give better SAR resolution?


Please check these:
https://people.eecs.ku.edu/~callen/826/ ... cs-F15.ppt

http://www.ece.uah.edu/courses/material ... rt1_11.pdf

https://earth.esa.int/documents/10174/9 ... ciples.pdf (page 14 onwards)

http://www.geo.uzh.ch/~fpaul/sar_theory.html

This, in turn, is driven by one of the main uses of SARs: to image the ground or targets. In both cases, the radar needs to be able to resolve very closely spaced scatterers. Specifically, resolutions in the order of a few feet are needed. To realize such resolutions in the range coordinate the radar uses wide bandwidth waveforms. To realize such resolutions in cross range very long antennas are required.


Basically to get high range resolution with radar you need to have very wide bandwidth. To get high resolution in azimuth (also known as cross-range resolution), a very long antenna is needed (which is done synthetically with SAR). I was talking about range resolution, where bandwidth is inversely proportional to resolution. Your formulas and pictures are about azimuth resolution. Basically the wider the bandwidth, the finer details can be resolved from the return signals in range given that there is enough processing power to do so. The links I provided tell much more about the issue.

Re: max range of the an/apg81 and AESA

Unread postPosted: 03 Oct 2016, 13:16
by hornetfinn
Dragon029 wrote:GaN will almost certainly make its way into the F-35 (unless an even better tech comes out / becomes mass produceable in the next decade or so). Increased output power may not seem ideal for a stealth aircraft, but it'll help with self-defensive EW and stand-off EW, and it might also allow the F-35 to boost the range of its MADL even further.


Actually increased output power can be very beneficial even for stealth aircraft if some thought is put into designing radar and other systems. Putting out more power does not directly mean the radar is more detectable. GaN technology gives many potential advantages that make it potentially much better than GaAs.

- Significantly higher output power of individual TR modules mean that it can create many more simultaneous beams or individual beams have higher power. There is no need to always blast at full power and modules can be run at low output power when high power is not needed. A lot of power is also good when a lot of power is needed. If enemy has VLO aircraft, having more radar power is better for detecting them and for jamming their radar.

- GaN allows much wider bandwidth which means it's much harder to detect and track. Current GaN systems can have 5-10 times the bandwidth of current GaAs systems. This means it can use 5-10 times more power and remain as tough to detect as GaAs system.

- GaN allows higher average power with the same peak power meaning that it will have better range performance while enemy ESM system performance stays the same as against GaAs system if all else remains equal.

Of course GaN also has other advantages like better efficiency. lower noise levels, smaller size and better reliability. Overall the improvement in performance can be as large as going from MSA or PESA radar to GaAs AESA. I'm sure F-35 will be the first mass produced fighter aircraft to adopt GaN radar system as that's where the development money really is and others are playing with pennies in comparison.

Re: max range of the an/apg81 and AESA

Unread postPosted: 03 Oct 2016, 13:42
by sferrin
I always think these, "what's the max range of radar X" questions are dumb. What's the max range of a flashlight? It's infinite. The photons will travel forever until they hit something. Without setting conditions the question is useless.

Re: max range of the an/apg81 and AESA

Unread postPosted: 03 Oct 2016, 18:09
by sprstdlyscottsmn
sferrin wrote:I always think these, "what's the max range of radar X" questions are dumb. What's the max range of a flashlight? It's infinite. The photons will travel forever until they hit something. Without setting conditions the question is useless.

I agree. I tend to think of the "standard" as a 1m^2 RCS target with positive closure in a "look-up" and ECM-free environment while using a normal volume search technique. Adjust accordingly from there.

Re: max range of the an/apg81 and AESA

Unread postPosted: 03 Oct 2016, 19:02
by vanshilar
sferrin wrote:I always think these, "what's the max range of radar X" questions are dumb. What's the max range of a flashlight? It's infinite. The photons will travel forever until they hit something. Without setting conditions the question is useless.


I feel the same way about when people quote supposed IR or IRST ranges. "No problem tracking the F-22 from 90 km away!" because of unstated assumptions sort of thing. It's like, yeah, even with our naked eyes we can detect stars from thousands of light years away, it really depends on what your assumptions and conditions are.

Re: max range of the an/apg81 and AESA

Unread postPosted: 04 Oct 2016, 11:13
by hornetfinn
sprstdlyscottsmn wrote:
sferrin wrote:I always think these, "what's the max range of radar X" questions are dumb. What's the max range of a flashlight? It's infinite. The photons will travel forever until they hit something. Without setting conditions the question is useless.

I agree. I tend to think of the "standard" as a 1m^2 RCS target with positive closure in a "look-up" and ECM-free environment while using a normal volume search technique. Adjust accordingly from there.


Agree totally with both of you. I'd like to add that range depends a lot also from probability of detection and false alarm rate. If we drop the pD to 0.01 percent and have high false alarm rate, a radar can have far better max range than another radar which has the pD of 90 percent and low false alarm rate. Only problem is that the first one would be totally useless as it would see thousands or millions of false targets along with the real target but range would be very long. There would be no way of knowing which target was false and which was real and thus the system would have zero usefullness. The latter would see very low number of false targets and would see the real target at significantly shorter range but confidence would be high that it is a real target. Of course the latter one would be useful as an actual radar system. Without knowing these two values along the things you listed, the comparison between two radar systems could be totally misleading.

Re: max range of the an/apg81 and AESA

Unread postPosted: 06 Oct 2016, 04:43
by eloise
hornetfinn wrote:
Please check these:
https://people.eecs.ku.edu/~callen/826/ ... cs-F15.ppt

http://www.ece.uah.edu/courses/material ... rt1_11.pdf

https://earth.esa.int/documents/10174/9 ... ciples.pdf (page 14 onwards)

http://www.geo.uzh.ch/~fpaul/sar_theory.html

This, in turn, is driven by one of the main uses of SARs: to image the ground or targets. In both cases, the radar needs to be able to resolve very closely spaced scatterers. Specifically, resolutions in the order of a few feet are needed. To realize such resolutions in the range coordinate the radar uses wide bandwidth waveforms. To realize such resolutions in cross range very long antennas are required.


Basically to get high range resolution with radar you need to have very wide bandwidth. To get high resolution in azimuth (also known as cross-range resolution), a very long antenna is needed (which is done synthetically with SAR). I was talking about range resolution, where bandwidth is inversely proportional to resolution. Your formulas and pictures are about azimuth resolution. Basically the wider the bandwidth, the finer details can be resolved from the return signals in range given that there is enough processing power to do so. The links I provided tell much more about the issue.

Thank hornet , very informative post

Re: max range of the an/apg81 and AESA

Unread postPosted: 07 Oct 2016, 20:03
by arian
hornetfinn wrote:
eloise wrote:
hornetfinn wrote:AESA has also the advantage of having much wider total bandwidth (frequency range) where it can operate. This makes them much more difficult to detect and much more resistant to electronic warfare. It also gives the advantage of giving much better resolution which is especially improtant in radar mapping and identification modes (like SAR/ISAR).

Why wide bandwidth give better SAR resolution?


Please check these:
https://people.eecs.ku.edu/~callen/826/ ... cs-F15.ppt

http://www.ece.uah.edu/courses/material ... rt1_11.pdf

https://earth.esa.int/documents/10174/9 ... ciples.pdf (page 14 onwards)

http://www.geo.uzh.ch/~fpaul/sar_theory.html

This, in turn, is driven by one of the main uses of SARs: to image the ground or targets. In both cases, the radar needs to be able to resolve very closely spaced scatterers. Specifically, resolutions in the order of a few feet are needed. To realize such resolutions in the range coordinate the radar uses wide bandwidth waveforms. To realize such resolutions in cross range very long antennas are required.


Basically to get high range resolution with radar you need to have very wide bandwidth. To get high resolution in azimuth (also known as cross-range resolution), a very long antenna is needed (which is done synthetically with SAR). I was talking about range resolution, where bandwidth is inversely proportional to resolution. Your formulas and pictures are about azimuth resolution. Basically the wider the bandwidth, the finer details can be resolved from the return signals in range given that there is enough processing power to do so. The links I provided tell much more about the issue.


So, what's the problem with Russian AESAs being so crappy in SAR both in resolution and range, do you think? Range of bandwidth or processing? Or both?

Re: max range of the an/apg81 and AESA

Unread postPosted: 10 Oct 2016, 14:29
by hornetfinn
arian wrote:So, what's the problem with Russian AESAs being so crappy in SAR both in resolution and range, do you think? Range of bandwidth or processing? Or both?


Probably both. Russian T/R module specs and general construction seems to be much like what Western T/R modules and fighter AESA prototypes were 25-30 years ago. This is what typical Western T/R modules looked like almost 30 years ago:

http://techdigest.jhuapl.edu/views/pdfs ... _Abita.pdf

Those performance figures are not that far away from figure for current Russian T/R modules. Processing power has been rather low in all Russian radars to this day.

Re: max range of the an/apg81 and AESA

Unread postPosted: 10 Oct 2016, 17:56
by playloud
What kind of price difference would we be talking about for an APG-81 with GaN vs GaA?

Re: max range of the an/apg81 and AESA

Unread postPosted: 11 Oct 2016, 09:25
by hornetfinn
playloud wrote:What kind of price difference would we be talking about for an APG-81 with GaN vs GaA?


This question is impossible to answer without knowing what the exact purpose and goal is. For example is the point getting maximum range performance which would mean quite a bit higher number of modules and would mean basically totally new antenna assembly and possibly other significant changes. That would be pretty expensive, likely something like 2-3 times the current unit cost. If the idea was to switch GaAs modules to GaN, it would be less costly, but still more expensive (currently, but changing quickly). If the idea was to have current performance level at lower power consumption and heat generation along with even higher reliability, it might actually be significantly cheaper. This is because much less modules would be needed with GaN and GaN can be used with less to no packaging, less cooling and prime power.

Another thing is that GaN cost has gone down quickly and seem to continue to do so as processes are improved and production is increased massively. I think it's time for fighter radars to move to GaN in about 10 years as right now GaAs is more than good enough and we can get a lot of other improvements to radar systems by then and not just the move from GaAs to GaN. I'm sure F-35 will receive GaN radar antenna at some point, probably in 2025-2030 timeframe.

Re: max range of the an/apg81 and AESA

Unread postPosted: 13 Oct 2016, 13:16
by spazsinbad
Sweden’s SAAB sweetens deal for Gripen jet
13 Oct 2016 DINAKAR PERI

"In an aggressive push to capture a share in India’s fighter aircraft market, Swedish aerospace major SAAB has offered its latest radar technology [GaN] as part of the Gripen fighter package...

...Explaining the developments in Advanced Electronically Scanned Array (AESA) radar, Lars Tossman, vice-president & Head of Communications of SAAB said that they were the first company to develop an AESA radar with Gallium Nitride which, he said, significantly enhances its efficiency and performance over the current AESA radars...."

Source: http://www.thehindu.com/news/national/s ... 212340.ece

Re: max range of the an/apg81 and AESA

Unread postPosted: 14 Nov 2016, 15:07
by bring_it_on
playloud wrote:What kind of price difference would we be talking about for an APG-81 with GaN vs GaA?


You would have to talk to industry insiders to try to find out the industrial cost of switching materials over to GaN and deliver the sort of scale the JSF as a program demands. I mean, we aren't talking about a couple of dozen radars a year here. That cost imho is a lot more significant than the actual unit cost of the hardware itself since the latter can be used to offset other cost down the road through higher up times, longer life, and less costly upgrades down the road.

At some stage the cost associated with creating that capacity may be more than justified by higher performance, and/or lower cost on account of other programs creating the broader capacity for you. However, unless there is a performance deficiency that can only be overcome by making an investment there are probably far better areas to invest the finite FOD resources than switching over to GaN radar. I agree a decade from now the equation may change but for now there are a lot of capability enhancements that will consume the mult-billion dollar follow on development program.

Re: max range of the an/apg81 and AESA

Unread postPosted: 12 Aug 2017, 18:50
by spazsinbad
Just a 50 second video about the APG-81 F-35 AESA radar: https://twitter.com/i/videos/tweet/896383342203023360

Re: max range of the an/apg81 and AESA

Unread postPosted: 21 Sep 2017, 21:04
by doge
"2010 Falcon 9 rocket & 2012 NASA's ATREX five rockets" is still in my heart...

APG-81andDAS.jpg


So I made this. (It's not so accurate, though... :oops: )

APG-81 range forecast.jpg


Would you choose what number(1,2,3,4,5,6)? (or Between what number and what number?)

Re: max range of the an/apg81 and AESA

Unread postPosted: 22 Sep 2017, 00:44
by white_lightning35
I would choose 1 probably. The upper ranges just don't seem right though due to the radar horizon. I can't see a fighter tracking something from 500km, much less 3400.

Re: max range of the an/apg81 and AESA

Unread postPosted: 22 Sep 2017, 09:01
by hornetfinn
AFAIK, the Falcon 9 rocket was not detected and tracked by AN/APG-81 but rather with EODAS only. I don't think it's possible to track such a long distance target with fighter sized radar within near future, no matter how large the RCS is. It also shows that against very hot targets emitting huge amount of thermal energy, IR system can easily outrange radar. It would be interesting to see how EOTS sees such a distant target.

I also think that those 5 NASA ATREX rockets were a lot closer than 1300 km. They were launched from Wallops Island and looking at the map and comparing it to that video it would seem the range is something like 100 to 200 km. Still very impressive range against such a small rocket. Terrier Malemute sounding rocket used is about similar size as large SAMs and has pretty similar launch properties. This is of course not really surprising given the origin of that rocket. I found it very impressive that AN/APG-81 tracked the very small and incredidbly fast second stage until and after the burnout. AFAIK; these rockets have top speed of something like Mach 12 or so. So, we can be pretty sure that any S-300/400 or similar launch will be detected by EODAS very far away and if within AN/APG-81 cone, will be tracked by the radar also. Of course there is EOTS also, which can look for it...

Another very impressive thing about EODAS was that it continuously tracked the burned out first stage to plummet to the ground. While definitely very hot after burnout, it should've been quite well cooled after heading to the ground for about a minute. We are also talking about object that is about the size of a regular air-dropped bomb.

Re: max range of the an/apg81 and AESA

Unread postPosted: 22 Sep 2017, 09:36
by Dragon029
hornetfinn wrote:AFAIK, the Falcon 9 rocket was not detected and tracked by AN/APG-81 but rather with EODAS only.

That appears to be correct. My estimate is that it's around 100km away (I did some perspective tracing off Google Earth):

https://www.youtube.com/watch?v=qF29GBSpRF4


One of the rockets launched that night was a Terrior Orion, which is about 10.7m long, 36cm in diameter at the rocket motor and around 1500kg with a payload. A Falcon 9 is about 47.7m long, 370cm in diameter and over 400,000kg.

Re: max range of the an/apg81 and AESA

Unread postPosted: 22 Sep 2017, 12:02
by doge
oh...I did not know that... :oops:
white_lightning35 wrote:

hornetfinn wrote:

Dragon029 wrote:

I'm sorry to have caused trouble...! :oops: :oops: And thank you very much for teaching me carefully!



Just in case,
I'll leave things that I modified and subdivided...
APG-81 range forecast2.jpg

Re: max range of the an/apg81 and AESA

Unread postPosted: 22 Sep 2017, 17:28
by sunstersun
would be kinda weird if they didn't upgrade to GAN.

Re: max range of the an/apg81 and AESA

Unread postPosted: 25 Sep 2017, 06:08
by glennwhitten
One of the posters on the video stated that the image was a digitally processed combination of SAR and DAS data. Sensor fusion?

Re: max range of the an/apg81 and AESA

Unread postPosted: 25 Sep 2017, 13:12
by hornetfinn
sunstersun wrote:would be kinda weird if they didn't upgrade to GAN.


That will happen without doubt, but will take some time. Currently GaN is used only in ground radars only but no doubt fighter radars will get GaN modules. But it's not easy thing to do and requires a lot of development work and money to achieve. It's not just that we take out GaAs modules and put new shiny GaN modules in their place. A lot of other things need to be redesigned and replaced and all this is not easy or cheap.

Re: max range of the an/apg81 and AESA

Unread postPosted: 25 Sep 2017, 13:36
by hornetfinn
glennwhitten wrote:One of the posters on the video stated that the image was a digitally processed combination of SAR and DAS data. Sensor fusion?


I doubt there is SAR used in those videos, but sensor fusion probably is. I think the video is EODAS imagery with virtual HUD symbology for sensor tracks. It seems like DAS and AN/APG-81 are working together to track the target. It seems like at first one sensor gets a track, then both sensors begin to track the target separately and then symbology quickly changes to single track.

Re: max range of the an/apg81 and AESA

Unread postPosted: 24 Nov 2017, 21:44
by stealthflanker
Hmm i wonder if we can work from the cooling capacity to predict maximum average power and then range. It appears for me at least, to work better than just guessing how much power emitted by the TRM.

Im curious if there is anything related to JSF cooling capacity made public ?

Theoritical limit for GaN power electronics is 300 Watt in X-band. However with liquid cooling (155 Kw/sqm) The possible emitted power could be emitted by the TRM would be 105.8 Watt peak and 24 Watt Average power (25% duty cycle, X-band. A-class Amplifier)

With 1676 modules it would be 177 Kilowatt Peak and 44.3 Kilowatt average power. Thing is of course whether the aircraft can carry that 155 Kw/sqm cooling capacity.

Re: max range of the an/apg81 and AESA

Unread postPosted: 25 Nov 2017, 01:51
by popcorn
glennwhitten wrote:One of the posters on the video stated that the image was a digitally processed combination of SAR and DAS data. Sensor fusion?

Maybe some EOTS imagery also?

Re: max range of the an/apg81 and AESA

Unread postPosted: 01 Sep 2018, 14:48
by doge
Wonder, interesting one sentence. (There is only this one line, No other explanation at all.)
https://www.mwrf.com/systems/radar-systems-make-history
Radar Systems Make History
Jack Browne | Jul 31, 2017
...
3. The AN/APG-81 radar system uses AESA technology and S-band frequencies for early detection.

It looks like a professional site, though...but, Is it mere write mistake? :roll: (Is S-band wrong and X-band is correct? I'm not sure...confusion... :roll: @@@)

Re: max range of the an/apg81 and AESA

Unread postPosted: 01 Sep 2018, 23:06
by swiss
doge wrote:Wonder, interesting one sentence. (There is only this one line, No other explanation at all.)
https://www.mwrf.com/systems/radar-systems-make-history
Radar Systems Make History
Jack Browne | Jul 31, 2017
...
3. The AN/APG-81 radar system uses AESA technology and S-band frequencies for early detection.

It looks like a professional site, though...but, Is it mere write mistake? :roll: (Is S-band wrong and X-band is correct? I'm not sure...confusion... :roll: @@@)


Yes X-band 8-12 GHz.

Re: max range of the an/apg81 and AESA

Unread postPosted: 01 Sep 2018, 23:16
by popcorn
vanshilar wrote:Hmm -- I thought the F-35's nose was sealed because they didn't need to service the radar for the lifetime of the individual article? If so, would they have to cut open the nose to install a GaN radar?

I don't think they welded it close. :mrgreen:

Re: max range of the an/apg81 and AESA

Unread postPosted: 06 Sep 2018, 18:21
by barrelnut
doge wrote:Wonder, interesting one sentence. (There is only this one line, No other explanation at all.)
https://www.mwrf.com/systems/radar-systems-make-history
Radar Systems Make History
Jack Browne | Jul 31, 2017
...
3. The AN/APG-81 radar system uses AESA technology and S-band frequencies for early detection.

It looks like a professional site, though...but, Is it mere write mistake? :roll: (Is S-band wrong and X-band is correct? I'm not sure...confusion... :roll: @@@)


There has been some patents describing an X-band radar system with wider band EW capabilities:

viewtopic.php?f=38&t=26802

Re: max range of the an/apg81 and AESA

Unread postPosted: 06 Sep 2018, 20:11
by castlebravo
barrelnut wrote:
doge wrote:Wonder, interesting one sentence. (There is only this one line, No other explanation at all.)
https://www.mwrf.com/systems/radar-systems-make-history
Radar Systems Make History
Jack Browne | Jul 31, 2017
...
3. The AN/APG-81 radar system uses AESA technology and S-band frequencies for early detection.

It looks like a professional site, though...but, Is it mere write mistake? :roll: (Is S-band wrong and X-band is correct? I'm not sure...confusion... :roll: @@@)


There has been some patents describing an X-band radar system with wider band EW capabilities:

viewtopic.php?f=38&t=26802


EW I can believe, but not for "early detection" as stated by the author. The antenna is just too small.