Methods and systems for near-field microwave imaging
First Claim
1. A method of near-field microwave imaging of a scene, the method comprising:
- acquiring multistatic array data with a multistatic array;
applying a multistatic-to-monostatic correction to the multistatic array data to form corrected multistatic array data;
Fourier transforming the corrected multistatic array data to form Fourier-domain data;
applying a phase shift to the Fourier-domain data to form phase-shifted Fourier-domain data, the phase shift corresponding to a distance between the multistatic array and the scene; and
inverse Fourier transforming the phase-shifted Fourier-domain data to form a representation of the scene,wherein applying the multistatic-to-monostatic correction comprises;
estimating multistatic reflections of a point scatterer as sampled by the multistatic array;
estimating monostatic reflections of the point scatterer as sampled in a plane of the multistatic array; and
weighting the multistatic array data by a ratio of the monostatic reflections of the point scatterer to the multistatic reflections of the point scatterer.
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Abstract
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.
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Citations
23 Claims
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1. A method of near-field microwave imaging of a scene, the method comprising:
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acquiring multistatic array data with a multistatic array; applying a multistatic-to-monostatic correction to the multistatic array data to form corrected multistatic array data; Fourier transforming the corrected multistatic array data to form Fourier-domain data; applying a phase shift to the Fourier-domain data to form phase-shifted Fourier-domain data, the phase shift corresponding to a distance between the multistatic array and the scene; and inverse Fourier transforming the phase-shifted Fourier-domain data to form a representation of the scene, wherein applying the multistatic-to-monostatic correction comprises; estimating multistatic reflections of a point scatterer as sampled by the multistatic array; estimating monostatic reflections of the point scatterer as sampled in a plane of the multistatic array; and weighting the multistatic array data by a ratio of the monostatic reflections of the point scatterer to the multistatic reflections of the point scatterer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 9, 21, 22)
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8. A method of near-field microwave imaging of a scene, the method comprising:
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acquiring multistatic array data with a multistatic array; applying a multistatic-to-monostatic correction to the multistatic array data to form corrected multistatic array data; Fourier transforming the corrected multistatic array data to form Fourier-domain data; applying a phase shift to the Fourier-domain data to form phase-shifted Fourier-domain data, the phase shift corresponding to a distance between the multistatic array and the scene; and inverse Fourier transforming the phase-shifted Fourier-domain data to form a representation of the scene, wherein acquiring the multistatic array data, applying the multistatic-to-monostatic correction, Fourier transforming the corrected multistatic array data, applying the phase shift to the Fourier-domain data, and inverse Fourier transforming the phase-shifted Fourier-domain data occurs at a rate of at least about 10 Hz.
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10. A system for imaging a scene, the system comprising:
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a multistatic array to acquire multistatic array data representing the scene; and a transceiver, operably coupled to the multistatic array, to transduce the multistatic array data; and a processor, operably coupled to the transceiver, to; apply a multistatic-to-monostatic correction to the multistatic array data to form corrected multistatic array data; Fourier transform the corrected multistatic array data to form Fourier-domain data; apply a phase shift to the Fourier-domain data to form phase-shifted Fourier-domain data, the phase shift corresponding to a distance between the multistatic array and the scene; and inverse Fourier transform the phase-shifted Fourier-domain data to form a representation of the scene, wherein the processor is configured to apply the multistatic-to-monostatic correction by; estimating multistatic sampled reflections of a point scatterer; estimating monostatic sampled reflections of the point scatterer; and weighting the multistatic array data by a ratio of the monostatic sampled reflections of the point scatterer to the multistatic sampled reflections of the point scatterer. - View Dependent Claims (11, 12, 13, 14, 15, 16, 18, 19)
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17. A system for imaging a scene, the system comprising:
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a multistatic array to acquire multistatic array data representing the scene; and a transceiver, operably coupled to the multistatic array, to transduce the multistatic array data; and a processor, operably coupled to the transceiver, to; apply a multistatic-to-monostatic correction to the multistatic array data to form corrected multistatic array data; Fourier transform the corrected multistatic array data to form Fourier-domain data; apply a phase shift to the Fourier-domain data to form phase-shifted Fourier-domain data, the phase shift corresponding to a distance between the multistatic array and the scene; and inverse Fourier transform the phase-shifted Fourier-domain data to form a representation of the scene, wherein the processor is configured to apply the multistatic-to-monostatic correction, Fourier transform the corrected multistatic array data, apply the phase shift to the Fourier-domain data, and inverse Fourier transform the phase-shifted Fourier-domain data at a rate of at least about 10 Hz.
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20. A system for imaging a scene, the system comprising:
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a multistatic array to acquire multistatic array data representing the scene; and a transceiver, operably coupled to the multistatic array, to transduce the multistatic array data; and a processor, operably coupled to the transceiver, to; apply a multistatic-to-monostatic correction to the multistatic array data to form corrected multistatic array data; Fourier transform the corrected multistatic array data to form Fourier-domain data; apply a phase shift to the Fourier-domain data to form phase-shifted Fourier-domain data, the phase shift corresponding to a distance between the multistatic array and the scene; and inverse Fourier transform the phase-shifted Fourier-domain data to form a representation of the scene, wherein the multistatic array comprises a plurality of tiled multistatic arrays, and wherein each tiled multistatic array in the plurality of tiled multistatic arrays has a length L<
R/4 given an imaging range R.
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23. A method of near-field microwave imaging of a scene, the method comprising:
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acquiring multistatic array data with a multistatic array; applying a multistatic-to-monostatic correction to the multistatic array data to form corrected multistatic array data; Fourier transforming the corrected multistatic array data to form Fourier-domain data; applying a phase shift to the Fourier-domain data to form phase-shifted Fourier-domain data, the phase shift corresponding to a distance between the multistatic array and the scene; and inverse Fourier transforming the phase-shifted Fourier-domain data to form a representation of the scene, wherein the multistatic array comprises a plurality of tiled multistatic arrays, wherein acquiring the multistatic array data comprises sampling each transmitter-receiver pair in each tiled multistatic array in the plurality of tiled multistatic arrays, and wherein each tiled multistatic array in the plurality of tiled multistatic arrays has a length L<
R/4 given an imaging range R.
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Specification