Phased Array Cladding for Grating Lobe Suppression
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Solution Overview
Problem
Sparse phased arrays, which reduce the number of antenna elements to lower costs, suffer from grating sidelobes that cause ghosting phenomena, especially at large scan angles, and existing post-processing remedies are computationally expensive and scene-dependent, making them impractical for real-time use in dynamic environments.
Innovation Solution
The use of a metamaterial cladding with a phase velocity exceeding that of the propagation medium allows for element spacing greater than λ/2, reducing the number of elements while restricting maximum scan angles to less than π/2 radians, thereby eliminating grating sidelobes through total internal reflection principles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the number of antenna elements is reduced to lower costs, then device complexity and cost are reduced, but grating sidelobes appear causing ghosting phenomena
Solution Approach 1:
A convex mount structure is introduced as an intermediary between the antenna elements and the propagation medium. This convex mount modifies the wave propagation path and phase distribution, enabling sparse array elements to achieve both cost reduction and sidelobe suppression through its geometric configuration
Solution Approach 2:
The invention changes the spatial arrangement parameter by positioning antenna elements on a convex surface rather than a flat plane. This parameter change in element geometry and positioning enables the array to maintain performance with fewer elements while avoiding grating sidelobes
2Device complexity
If element spacing is increased beyond λ/2 to reduce element count, then device complexity is reduced, but grating sidelobes are generated
Solution Approach 1:
The invention transitions from a two-dimensional planar array to a three-dimensional convex surface array. By distributing elements along the curved surface of the convex mount, the system achieves better spatial utilization and phase control, allowing larger spacing without generating grating sidelobes
3Measurement precision
If post-processing deconvolution algorithms are applied to remove ghosting, then image quality is improved, but processing time increases significantly
Solution Approach 1:
The convex mount configuration performs preliminary optimization of the antenna element distribution and phase distribution before signal transmission/reception. This pre-configuration prevents grating sidelobes from forming in the first place, eliminating the need for time-consuming post-processing deconvolution algorithms
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 sidelobe-free scanning with reduced element density, improving image reconstruction efficiency and suitability for real-time use in dynamic environments like security screening without the need for complex, scene-dependent post-processing.
Implementation Method 1
The use of a metamaterial cladding with a phase velocity exceeding that of the propagation medium allows for element spacing greater than λ/2, reducing the number of elements while restricting maximum scan angles to less than π/2 radians, thereby eliminating grating sidelobes through total internal reflection principles
Data Source
AI summary
Grating lobe free scanning in a phased array with sparse element spacing is obtained by restricting the maximum scan angle for elements in the array, and cladding the array. Array elements may be integrated into the cladding.