Analog Beamforming Weights for Wideband Beam Squint Mitigation
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Solution Overview
Problem
Beam squint in wideband phased array antennas causes power loss at frequencies other than the design frequency due to frequency-dependent beam steering, which existing hardware solutions like True Time Delay and spatio-spectral beamforming increase complexity and cost.
Innovation Solution
Analog beamforming technique that adjusts beam shape to compensate for squint effects by maximizing array gain across a bandwidth using a weighted-sum method, deriving a closed-form beamforming weight vector as the complex conjugate of array responses at multiple frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If True Time Delay hardware solution is used to combat beam squint effect, then beam focus accuracy is improved, but circuit complexity and implementation cost increase significantly
Solution Approach 1:
The patent replaces the mechanical hardware-based True Time Delay system with a mathematical signal processing approach. By deriving closed-form beamforming weight vectors that incorporate frequency-dependent phase compensation, the system achieves beam squint mitigation through computational methods rather than physical time-delay circuits, thereby reducing circuit complexity while maintaining beam focus accuracy.
Solution Approach 2:
The patent changes the parameters of the beamforming weights by deriving closed-form expressions that explicitly account for frequency variations. The weight vectors are designed to compensate for beam squint across the entire bandwidth by adjusting phase parameters based on frequency, allowing a single set of weights to maintain focus accuracy without requiring complex hardware adjustments.
2Measurement precision
If spatio-spectral beamforming with analog FFT is employed to reduce beam squint, then beam steering accuracy is improved, but the number of phase shifters and system complexity increase
Solution Approach 1:
The patent extracts and compensates for the beam squint effect mathematically by deriving closed-form weight vectors that include frequency-dependent phase correction terms. Instead of using analog FFT to separate frequency slices and applying separate phase shifters to each slice, the invention extracts the essential compensation needed across the entire bandwidth through a unified mathematical formulation, reducing the number of required phase shifters.
Solution Approach 2:
The patent creates a universal beamforming weight vector formulation that works across the entire frequency bandwidth without requiring separate processing for different frequency slices. The closed-form solution provides multi-functional capability, handling beam steering and beam squint compensation simultaneously for all frequencies within the bandwidth using a single set of weights, thereby eliminating the need for multiple dedicated phase shifters.
3Measurement precision
If beamforming codebook density is increased to counter beam squint, then beam coverage accuracy is improved, but beamforming time and latency increase
Solution Approach 1:
The patent performs preliminary action by pre-calculating closed-form beamforming weight vectors that inherently compensate for beam squint across the entire bandwidth. Instead of requiring a dense codebook with many pre-computed beams to cover squint-induced angle variations, the invention pre-computes a single set of optimized weights that account for frequency-dependent effects, reducing the number of codebook entries needed and thereby reducing beamforming time and latency.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A method of beam steering is provided to address the squint effect that occurs in phased array antennas when wideband signals are transmitted. Beam steering weights are computed based on an optimization that takes into account performance at a set of frequencies across a bandwidth of interest, including at least endpoints of the bandwidth, and a design frequency.