Sparse Radar Antenna Grating Lobe Suppression
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Solution Overview
Problem
Traditional Active Electronically Steerable Antennas (AESAs) are limited by the large number of microwave receivers and digital channels required, leading to high costs, power consumption, and cooling system expenses, especially for narrow beam antennas, due to the need for antenna elements spaced at half a wavelength or less to avoid grating lobes.
Innovation Solution
A beamforming method that allows receive antenna elements to be sparsely mounted with spacings greater than half a wavelength by generating digital signals through frequency down-conversion and analog-to-digital conversion, then aligning and combining these signals to suppress grating lobes through sum and product beamforming, reducing the number of required antenna elements while maintaining a narrow main lobe and suppressing grating lobes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If antenna elements are spaced at half a wavelength or less to avoid grating lobes, then grating lobe suppression is achieved, but the number of antenna elements and receivers increases
Solution Approach 1:
The patent changes the spacing parameter of antenna elements from the conventional half-wavelength constraint to larger spacings (greater than half a wavelength), thereby reducing the number of elements required while managing grating lobes through digital signal processing rather than physical constraints
Solution Approach 2:
The patent replaces the mechanical/physical constraint of element spacing with a digital signal processing solution, using beamforming algorithms to suppress grating lobes computationally instead of relying on physical proximity of elements
2Reliability
If the number of microwave receivers is increased to support more antenna elements, then beamforming performance is maintained, but cost and power consumption increase
Solution Approach 1:
The patent changes the operational parameters of the receivers by using digital signal processing with larger antenna element spacings, allowing fewer receivers to achieve the same beamforming performance through computational methods rather than requiring proportional hardware increases
3Quantity of substance
If antenna elements are sparsely mounted with larger spacings, then the number of receivers is reduced, but grating lobes increase
Solution Approach 1:
The patent substitutes physical constraints with digital processing by using beamforming algorithms to suppress grating lobes that arise from sparse antenna element configurations, enabling large spacings without the traditional penalty of significant grating lobe formation
Solution Approach 2:
The patent introduces digital signal processing as an intermediary between the sparsely mounted antenna elements and the final beamformed output, using computational methods to eliminate the harmful effects of large element spacings
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 method enables the use of fewer receive antenna elements, reducing costs and power consumption while maintaining performance, and is particularly beneficial for wideband FMCW radars by allowing digital synthesis of multiple narrow receive beams within a wide transmit beam.
Implementation Method 1
receiving reflected radar signals at the receive antenna elements
Implementation Method 2
frequency down-conversion
Data Source
AI summary
An active electronically steerable receive antenna may comprise an antenna array that includes multiple receive antenna elements. Reflected radar signals may be received at the receive antenna elements, and received signals may be obtained from the receive antenna elements. The received signals may be processed via at least frequency down-conversion, analog-to-digital conversion, generation of digital signals, and alignment of the received signals or the digital signals for a predetermined angle of incidence. Multiple signals including a sum beamforming signal and a product beamforming may be multiplied to determine a beamformed signal. The sum beamforming signal and the product beamforming signal may be respectively determined by summing or multiplying at least two of the digital signals. The product beamforming signal may be a grating lobe suppression signal that suppresses grating lobes of the sum beamforming signal when multiplied with the sum beamforming signal.