Luneberg Lens


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Luneberg lens

[′lü·nə‚bərg ‚lenz]
(electromagnetism)
A type of antenna consisting of a dielectric sphere whose index of refraction varies with distance from the center of the sphere so that a beam of parallel rays falling on the lens is focused at a point on the lens surface diametrically opposite from the direction of incidence, and, conversely, energy emanating from a point on the surface is focused into a plane wave. Accurately spelled Luneburg lens.

Luneberg Lens

 

a lens antenna in which the maximum of the directivity pattern may be controlled over a wide angular sector. It was proposed by the American scientist R. K. Luneberg in 1944. It is used mainly in radar installations in the centimeter wavelength range.

A Luneberg lens is spherical or cylindrical and is characterized by the fact that the index of refraction of the lens material is not constant throughout the lens but rather is a function of the distance to its center (for a spherical lens) or its axis (for a cylindrical lens). This function is chosen so that the wavefront becomes a plane after passing through the lens. By shifting the radiator along the lens surface, the direction of maximum radiation may be varied through a solid angle of up to without altering the shape of the directivity pattern.

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References in periodicals archive ?
[31.] Gutman, A., "Modified luneberg lens," Journal of Applied Physics, Vol.
The HMD can carry smoke, IR flares, passive or active radar augmenters or a Luneberg lens (a radar signal reflector).
Intended as a radar decoy, Delilah's mission payload can be either a Luneberg lens or what are described as "active radio-frequency repeaters" operating in the A, C and L bands.
Tenders are invited for Procurement of bistatic luneberg lens xbr 0.85
Ujiie, "A plate Luneberg lens with the permittivity distribution controlled by hole density," Electronics and Communications in Japan (Part I: Communications), Vol.
These requirements stimulate an increasing interest in the development of Luneberg lens antennas (LLA) with multiband and multi-polarized feed-system.
Nie, "Study on multiple frequencies and polarizations feed technique in luneberg lens antenna," Intelligent Signal Processing and Communication Systems (ISPACS) Int.
T., "The electromagnetic theory of the spherical luneberg lens," Appl.
[DELTA][[epsilon].sub.i+1] is the increment permittivity, and [[sigma].sub.p] represents the control precision of permittivity for each layer, especially for the composite foam materials for Luneberg lens. The available low loss materials ([[epsilon].sub.i]: 1.0 ~ 5.0) can also be picked up from the database.
On the other hand, for a conventional 2-layer uniform Luneberg lens antenna (LLA) with the same dimensions and dielectric losses, the corresponding aperture efficiencies are only 15.8% and 10.7%, respectively.
Vinogradov, "Scattering by a Luneberg lens partially covered by a metallic cap," Journal of Electromagnetic Waves and Applications, Vol.