Offset Luneburg Lens Array Layout for Grating Lobe Reduction
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Solution Overview
Problem
Existing radio frequency (RF) antenna arrays with spherical Luneburg lenses face challenges in efficiently directing RF signals from multiple directions without signal interference and grating lobes, particularly when increasing capacity beyond a certain limit.
Innovation Solution
The arrangement of two or more spherical lenses in an offset fashion, with individual feed elements tilted to minimize signal intersections and grating lobes, allows for improved signal performance and reduced interference between adjacent lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple lenses are arranged on a plane in a linear fashion to increase capacity, then the number of supported beams increases, but signal intersections between adjacent lenses occur and grating lobes are generated
Solution Approach 1:
The patent transitions from a two-dimensional planar arrangement of lenses to a three-dimensional configuration where lenses are positioned at different heights (vertical offsets). This dimensional change allows adjacent lenses to be staggered vertically, preventing signal paths from intersecting between lenses while maintaining the increased beam capacity, thereby eliminating grating lobe formation.
2Productivity
If the beam width is decreased to increase capacity beyond 12 beams, then more beams can be supported, but the utility of the device is restricted
Solution Approach 1:
By arranging lenses in three dimensions with vertical offsets, the system can support more beams without reducing individual beam width. The vertical staggering provides additional spatial separation that maintains beam utility and coverage characteristics while increasing the total number of supported beams beyond the conventional 12-beam limit.
3Productivity
If a single large Luneburg lens is used to increase capacity, then more beams can be supported, but manufacturing difficulty and size/weight issues arise
Solution Approach 1:
The patent divides the antenna system into multiple smaller, separate lens elements arranged in a three-dimensional configuration. Each lens maintains manageable size for manufacturing while the collective array achieves the capacity of a much larger single lens. This segmentation approach avoids the manufacturing difficulties and practical issues associated with large single lenses while supporting increased beam capacity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances signal quality by reducing signal impingement and distortion, thereby improving the overall performance of the RF antenna array without increasing the size or weight of individual lens elements.
Implementation Method 1
a lens capable of focusing radio frequency (RF) or microwave frequencies can be used. One suitable lens is a Luneburg lens, a spherically (or substantially spherical) symmetrical lens with a refractive index gradient
Implementation Method 2
a reflector (e.g., a parabolic reflector) that serves to focus electromagnetic energy in the desired spectral range on a feed that is positioned at the focal point
Data Source
AI summary
A lens elements array comprises at least two lens elements aligned along an alignment axis. Each lens element includes a spherical lens and a feed element. The feed elements are tilted such that the RF signals generated by the feed elements have major axes form an angle (preferably between 5° and 30°) other than a perpendicular angle with respect to the alignment axis. The combined RF signals produced collectively by these feed elements have amplitude that has minimal dips across the array. The feed elements that are farther away from the center of the array have higher levels of tilts than the feed elements that are closer to the center of the array.