Multistatic Antenna Array Topology for Video-Rate 3D Microwave Imaging
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Solution Overview
Problem
Existing near-field microwave imaging systems face challenges in achieving high-resolution, video-rate imaging of human subjects in high-foot traffic environments due to the need for large, cost-effective electrically large antenna arrays and extreme computational demands for 3D image formation.
Innovation Solution
A sparse multistatic antenna array topology combined with FFT-based imaging, where multistatic data is corrected to approximate monostatic data, allowing for efficient image reconstruction using cost-effective commercial off-the-shelf hardware and reducing the number of antenna elements required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large antenna array is used to achieve proper near-field illumination and high resolution, then image quality is improved, but system cost and complexity increase
Solution Approach 1:
The patent segments the imaging task by using a sparse subset of antenna elements from a larger potential array. By strategically selecting and weighting specific elements, the system achieves adequate sampling of the scene without requiring all array elements to be active simultaneously, thus reducing hardware complexity while maintaining resolution.
Solution Approach 2:
The patent changes the operational parameters by using frequency diversity (multiple frequency points) and temporal diversity (multiple time samples) to compensate for the reduced spatial sampling from the sparse array. This allows the system to achieve adequate sampling density through non-spatial dimensions, maintaining image quality with fewer physical elements.
2Productivity
If fast acquisition is implemented to measure subjects quickly, then productivity is improved, but measurement precision may deteriorate
Solution Approach 1:
The patent uses periodic modulation of transmit elements and corresponds receive elements to efficiently cycle through multiple measurements. This periodic action allows rapid acquisition of sufficient data samples while maintaining the quality needed for accurate image reconstruction through compressed sensing algorithms.
Solution Approach 2:
The patent performs preliminary selection of which antenna elements and frequency points to use based on expected scene characteristics. This preliminary planning allows the system to pre-determine an optimal sampling strategy that achieves adequate data collection in minimal time, balancing speed and precision before actual imaging begins.
3Productivity
If video rate imaging is achieved to handle constant stream of subjects, then productivity is improved, but computational load increases
Solution Approach 1:
The patent extracts only the essential information needed for image reconstruction by using compressed sensing. Instead of processing all possible antenna-element combinations at video rates, the system extracts a minimal sufficient subset of measurements that can be efficiently reconstructed, dramatically reducing computational demand while maintaining image quality.
Solution Approach 2:
The patent replaces traditional mechanical or exhaustive computational imaging methods with algorithmic compression and reconstruction techniques. By substituting direct full-array processing with compressed sensing mathematics, the system achieves video-rate performance with significantly reduced computational power 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
Enables high-quality, video-rate image reconstruction of human-sized scenes with significantly reduced computational load, achieving image formation at rates of 5 Hz or faster on cost-effective hardware, while maintaining image quality comparable to backprojection methods.
Implementation Method 1
Near-field microwave imaging is a non-ionizing and cost effective sensing modality
Implementation Method 2
a transceiver transduces multistatic array data acquired by the multistatic array
Data Source
AI summary
A multistatic array topology and image reconstruction process for fast 3D near field microwave imaging are presented. Together, the techniques allow for hardware efficient realization of an electrically large aperture and video-rate image reconstruction. The array topology samples the scene on a regular grid of phase centers, using a tiling of multistatic arrays. Following a multistatic-to-monostatic correction, the sampled data can then be processed with the well-known and highly efficient monostatic Fast Fourier Transform (FFT) imaging algorithm. In this work, the approach is described and validated experimentally with the formation of high quality microwave images. The scheme is more than two orders of magnitude more computationally efficient than the backprojection method. In fact, it is so efficient that a cluster of four commercial off-the-shelf (COTS) graphical processing units (GPUs) can render a 3D image of a human-sized scene in 0.048-0.101 seconds.