F-35 Luneburg lens radar reflector

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spazsinbad

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Unread post30 Dec 2019, 10:55

Interesting - zoom zoom....
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notkent

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Unread post30 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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spazsinbad

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Unread post30 Dec 2019, 13:24

A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
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falcon.16

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Unread post31 Dec 2019, 14:18

what frequencies work a luneberg lens? i think only in short waves...
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hornetfinn

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Unread post31 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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archeman

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Unread post31 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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marsavian

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Unread post01 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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spazsinbad

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Unread post01 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
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doge

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Unread post01 Mar 2020, 04:46

Another Angle 8)
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