F-35 Luneburg lens radar reflector

Discuss the F-35 Lightning II
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by spazsinbad » 30 Dec 2019, 10:55

Interesting - zoom zoom....
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F-35lunebergLensZOOMzoom.jpg


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by notkent » 30 Dec 2019, 13:10

The design of the cap may be to vary the gain based on angle of incoming radar instead of just adding a fixed amount of gain in all directions. If the cap was rotatable then it would prevent any true mapping of the stealth profile of the plane.

Also a guess that the notches may be tuned for specific frequencies of radar. A manufacture has this to say about Luneberg reflectors have a homogeneous response over a wide angle;

The Luneberg reflector gives an homogeneous response inside a wide angle. It is an ideal passive responder, perfect for highlighting, and eventually monitoring the radar target to which it is attached, with a high level of security.
The Luneberg lens is the most efficient passive radar reflector available.
The Luneberg reflector requires no power supply nor maintenance.


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by spazsinbad » 30 Dec 2019, 13:24



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by falcon.16 » 31 Dec 2019, 14:18

what frequencies work a luneberg lens? i think only in short waves...
https://aeropathfinder.blogspot.com/


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by hornetfinn » 31 Dec 2019, 14:47

falcon.16 wrote:what frequencies work a luneberg lens? i think only in short waves...


They can work in any possible frequency. You can make Luneburg lens for any frequency, but naturally they have best effect at some frequency range. But Luneburg lens is pretty wideband in any case and nothing stops using several of them to cover wider frequency range.


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by archeman » 31 Dec 2019, 20:40

notkent wrote:The design of the cap may be to vary the gain based on angle of incoming radar instead of just adding a fixed amount of gain in all directions. If the cap was rotatable then it would prevent any true mapping of the stealth profile of the plane.

Also a guess that the notches may be tuned for specific frequencies of radar. A manufacture has this to say about Luneberg reflectors have a homogeneous response over a wide angle;

The Luneberg reflector gives an homogeneous response inside a wide angle. It is an ideal passive responder, perfect for highlighting, and eventually monitoring the radar target to which it is attached, with a high level of security.
The Luneberg lens is the most efficient passive radar reflector available.
The Luneberg reflector requires no power supply nor maintenance.


Kinda looks like the guts of an old Xband cavity magnatron.

https://en.wikipedia.org/wiki/Cavity_ma ... iagram.png
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by marsavian » 01 Jan 2020, 16:39

falcon.16 wrote:what frequencies work a luneberg lens? i think only in short waves...


1 to 40 GHz according to Spaz link just above your post

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p.s. pdf link now broken


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by spazsinbad » 01 Jan 2020, 17:02

Attached via broken link: 2013 4th edition Electronic Warfare and Radar Systems Engineering Handbook 455 page PDF.
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EW 2013 Warfare NAWCWD TP 8347.pdf
(6.46 MiB) Downloaded 3606 times


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by doge » 01 Mar 2020, 04:46

Another Angle 8)
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F35_tutkaheijastin_2.jpg


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by doge » 01 Feb 2021, 16:28

Valuable shot of installing / removing the Luneburg lens. :shock: Wow
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Luneburg lens (1), 200907-M-MS099-781 VMFA-211 F-35B Lightning II Joint Strike Fighter at Royal Air Force Station Marham, United Kingdom (UK) on 07 September, 2020.jpg
Luneburg lens (2), 200907-M-MS099-712 VMFA-211 F-35B Lightning II Joint Strike Fighter at Royal Air Force Station Marham, United Kingdom (UK) on 07 September, 2020.jpg


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by jessmo112 » 01 Feb 2021, 19:04

doge wrote:Another Angle 8)



Does anyone know, if they can be dumped in flight?


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by zhangmdev » 01 Feb 2021, 21:05

Unlikely. Ejecting those things in-flight could strike the vertical tails.


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by spazsinbad » 01 Feb 2021, 22:39

zhangmdev wrote:Unlikely. Ejecting those things in-flight could strike the vertical tails.

:shock: Plus you'd have to give the poor old maintainer a parachute one hopes. :devil:


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by usafr » 02 Feb 2021, 16:04

It is quite obvious thae metallic device in the hole has a hinge bolt and rotates outbound through the slot in the cover.

Seems to me we need to be looking for a picture of the device not just "installed" on the jet, but in actual "use."


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by doge » 11 Apr 2022, 05:29

Belly Radar Reflector. 8)
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abdomen radar reflector F-35A gifu airbase JASDF AX-29-8729 ⁡Feb 18, 2022.jpg


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