Dual-Planar Antenna Array Interleaving Grating Lobes
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Solution Overview
Problem
High-frequency wireless communication systems face a trade-off between high antenna gain and directivity, which narrows coverage, and broad coverage, which sacrifices beam directivity and efficiency, as they often generate grating lobes that draw power from the main beam.
Innovation Solution
A dual-band antenna system comprising two planar arrays with different element spacings operating in distinct frequency bands, where the second array is displaced in the z-dimension and positioned in the near-field of the first array, interleaving grating lobes to enhance coverage without suppressing them, allowing for broader coverage while maintaining directivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the antenna array is designed to achieve high antenna gain and directivity, then the beam focusing capability is improved, but the coverage area is reduced
Solution Approach 1:
The antenna array is divided into multiple sub-arrays, each capable of generating its own main lobe and grating lobes. By segmenting the array and independently controlling each sub-array's beamforming, the system can create multiple simultaneous beams that cover different spatial regions, thereby expanding overall coverage while maintaining high gain in each direction
Solution Approach 2:
The patent utilizes the grating lobes, which are typically harmful side lobes, and repositions them in the spatial domain by adjusting element spacing and phase shifts. This transforms the problem from a two-dimensional trade-off (gain vs. coverage) into a three-dimensional solution where grating lobes are strategically placed in angular space to fill coverage gaps without compromising main beam directivity
2Area of stationary object
If the antenna array is designed to achieve broad coverage, then the coverage area is improved, but the beam directivity and efficiency are reduced
Solution Approach 1:
The patent converts the harmful grating lobes, which normally draw power from the main beam and reduce efficiency, into beneficial coverage-extending beams. By adjusting the element spacing to be greater than half a wavelength and applying specific phase shifts, the grating lobes are positioned to cover additional angular regions, effectively transforming power-wasting artifacts into useful coverage-extending beams that maintain overall system efficiency
3Power
If the element spacing is increased to reduce grating lobes, then the main beam quality is improved, but coverage area is reduced
Solution Approach 1:
Instead of reducing element spacing to eliminate grating lobes (conventional approach), the patent inverts the strategy by increasing element spacing beyond the traditional half-wavelength limit. This inversion causes grating lobes to appear at predictable angular positions, which are then deliberately used to expand coverage rather than being suppressed, thereby improving both main beam quality and overall coverage simultaneously
Data Source
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AI summary
An embodiment antenna having first and second planar arrays. The first array has a first element spacing in an x-dimension and a y-dimension and is operable in a first frequency band. The second array has a second element spacing in the x-dimension and the y-dimension, and is operable in a second frequency band. The second planar array is displaced from the first planar array in a z-dimension for co-aperture operation of the arrays, and is disposed parallel to and in a near-field of the first planar array. Elements of the second planar array are disposed and steerable, in a u-v plane for interleaving a first plurality of grating lobes generated by the first planar array with a second plurality of grating lobes generated by the second planar array.