Flat GRIN Microwave Lens With Short Focal Length and Wide Beam Scan
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Solution Overview
Problem
Current antenna systems for satellite communications face limitations in achieving low-profile, wideband, and cost-effective designs with wide-angle beam steering capabilities, particularly in mechanically steered and electronically steered phased arrays, which are often bulky, expensive, and limited by metamaterials or dispersive structures.
Innovation Solution
The development of a compact, low-profile all-dielectric gradient-index (GRIN) lens antenna design using a ray tracer algorithm and optimization techniques to efficiently model and optimize the refractive index profile, allowing for rapid simulation and verification of microwave lens designs, reducing the need for computationally expensive full-wave solvers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If conventional microwave lens antennas are designed using traditional methods, then they achieve good focusing capability, but they become heavy and bulky
Solution Approach 1:
The patent applies parameter changes by transitioning from homogeneous dielectric lenses to gradient-index (GRIN) lenses with spatially varying refractive indices. The refractive index profile is optimized to achieve superior focusing capability with reduced aperture size, directly addressing the contradiction between performance and physical dimensions. This parameter optimization enables compact antenna designs that maintain high directivity and beam steering capability.
Solution Approach 2:
The patent introduces dimensional changes by developing low-profile lens designs that reduce the depth dimension while maintaining aperture area. The GRIN lens structure achieves equivalent or superior focusing performance in a reduced z-direction thickness, effectively moving the solution from traditional bulky spherical lenses to thin, planar configurations suitable for modern satellite terminal applications.
2Length of stationary object
If transformation optics techniques are applied to create flat lenses, then profile is reduced, but strongly anisotropic and magnetic materials are required which are not found in nature
Solution Approach 1:
The patent resolves the material availability issue by changing the approach from transformation optics requiring anisotropic magnetic materials to GRIN lens design using only isotropic dielectric materials. The refractive index gradient is achieved through careful selection and arrangement of conventional dielectric materials with different permittivities, making the lens manufacturable with standard materials while maintaining the desired thin profile and electromagnetic focusing performance.
Solution Approach 2:
The patent employs composite material structures by combining multiple isotropic dielectric materials with different refractive indices in a gradient arrangement. This composite approach creates the effective GRIN profile needed for flat lens operation without requiring exotic single materials, enabling practical fabrication using layered or continuously varying dielectric compositions.
3Ease of manufacture
If approximation procedures are used to obtain all-dielectric lenses from TO specification, then material requirements are simplified, but unacceptable degradation to device performance occurs
Solution Approach 1:
The patent avoids performance degradation by fundamentally changing the design methodology from approximate TO transformations to exact GRIN lens synthesis. The refractive index profile is directly optimized for the desired focusing and beam steering performance, and then discretized into manufacturable layers. This direct optimization approach maintains high aperture efficiency and beam quality while using simple isotropic materials.
4Measurement precision
If full-wave solvers are used for lens design verification, then accurate results are obtained, but computational time and resources are excessive
Solution Approach 1:
The patent applies segmentation by dividing the verification process into two stages: rapid geometric optics ray-tracing for initial design optimization and aperture efficiency evaluation, followed by selective full-wave solver verification only for final design confirmation. This segmented approach reduces overall computational time by using the faster method for the majority of design iterations and reserving the computationally intensive method for final validation.
Solution Approach 2:
The patent implements preliminary action by performing ray-tracing based aperture efficiency calculations before full-wave solver verification. This preliminary assessment quickly identifies promising design configurations and eliminates poor candidates, so that full-wave simulations are only performed on a small subset of optimized designs, dramatically reducing total computational resource requirements.
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 approach enables the creation of lightweight, high-aperture-efficiency antennas with wide beam steering capabilities, significantly reducing design time and computational resources while achieving performance comparable to or exceeding existing systems.
Implementation Method 1
Lenses at microwave frequencies generate a high antenna directivity by bending the microwave electromagnetic fields with a combination of carefully designed geometry and (potentially) inhomogeneous dielectric constant profile within the lens
Data Source
AI summary
A system designs a thin and relatively flat microwave focusing lens that can produce multiple simultaneous beams, using readily-available isotropic dielectric materials, and having a gradient-index (GRIN) profile. The design optimizes the lens to achieve beam scanning and/or multiple beams over a wide field of regard (FOR) with broad bandwidth and a very short focal length compared with conventional lenses. The lens can be used individually or as an element in a more complex antenna having multiple lenses in various orientations that are independently switched, selected and/or excited simultaneously as elements in a phased array. The antenna terminal incorporates such lens into an array of lenses along with one or more feeds to produce single or multiple beams covering a broad field of regard for such applications as satellite communications on-the-move, cellular, broadband point-point or point-multipoint and other terrestrial or satellite communications systems. The lens and array design support multiple simultaneous independently steerable beams as well as null placement for interference cancellation.