A Microwave Time Reversal Algorithm for Imaging Extended Defects in Dielectric Composites

Mukherjee, Saptarshi; Mays, R. Owen; Tringe, Joseph W.

doi:10.1109/tci.2021.3125925

Cited by 7 publications

(5 citation statements)

References 49 publications

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“…A short microwave pulse signal is usually used as a source in the microwave TR algorithm to achieve efficient focusing. The pulse width determines the range resolution of the algorithm [22]. The source used in this paper is a Gaussian-modulated pulse given by…”

Section: Microwave Tr Algorithm Based On Fdtd Methodsmentioning

confidence: 99%

“…However, these works do not involve the detection of buried damage in composite materials. Moreover, the detection of extended defects in dielectric composites is studied based on the combination of time-resolved information from multiple sources [22]. But this research is based on the case that composite materials exist in free space.…”

Section: Introductionmentioning

confidence: 99%

“…It has been applied in many fields, including restoration of star field image [26], shallow subsurface object localization [27], breast cancer detection based on microwave TR algorithm [28][29][30] and so on. TIEM has been introduced and proved in damage detection of dielectric materials [21,31] and dielectric composites [5,6,22] based on microwave TR algorithm. Due to the auto-focus property, the accumulated energy at the target location will be larger than at other locations.…”

Section: Introductionmentioning

confidence: 99%

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Microwave time reversal for nondestructive testing of buried small damage in composite materials

An,

Li,

Long

et al. 2024

Inverse Problems

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Composite materials are widely applied in aerospace, civil engineering, and sports equipment. Various damages produced during fabrication and long-term use can destroy its original mechanical properties, which brings safety and structural healthy concerns. Microwave imaging based on time reversal is one of the most promising nondestructive testing (NDT) methods for portable, low-cost, and accurate testing with the advantages of auto-focus and super-resolution. This paper applied microwave time reversal for the detection of buried small damage in composites backed by metal plates. Strong reflection from composite-metal interfaces brings challenges in successfully achieving time-reversal auto-focusing on small and weak-scattering damages in composites. Traditional target localization methods, including the entropy regularization method (ERM) and time-integrated energy method (TIEM), may result in the wrong localization of small damages. The main contribution of this paper is that the localization problem caused by the strong reflection from metal plates is revealed first, and the target initial reflection method (TIRM) from through-wall-radar imaging is introduced to solve it. The performance of three target localization methods is investigated, and the physical reasons for failure or successful localization are discussed in detail. Some performance influence factors, such as the arrangement of receivers or the total time step of received signals, are also discussed. Good performance for the detection of a single small damage with a weak scattered signal is achieved, and the performance for detecting multiple damages is studied. All time-reversal simulations are carried out based on the finite-difference time-domain (FDTD) method.

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Section: Microwave Tr Algorithm Based On Fdtd Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Microwave time reversal for nondestructive testing of buried small damage in composite materials

An,

Li,

Long

et al. 2024

Inverse Problems

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“…Practically for our cases, the reference section does not need to be identically similar in geometry and dielectric properties. We have previously studied the effect of an imperfect reference sample on the detection capabilities of the time reversal algorithm and found out that small uncertainty in the reference sample should not strongly affect the time-reversed signal [46]. Thus, for our reference samples, we have a control of an approximately similar wood trunk section from a similar tree trunk and rough estimate of the trunk diameter.…”

Section: ) Background Subtraction Stepmentioning

confidence: 99%

A Microwave Tomography System Using Time-Reversal Imaging for Forestry Applications

et al. 2022

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A healthy urban forest is important to improve both human health and overall environmental quality. There is currently a lack in technology that has the ability to evaluate living trees in their natural environment without invasive destructive sampling. This work presents a cost-effective, real-time microwave tomography system for practical forestry applications. The scattering measurement system is designed using wide band microstrip monopole antennas (1-5 GHz) and coupled to a switching matrix and a controlling software for automated real-time data collection. A time reversal signal processing algorithm is developed for performing imaging, based on the measurements. The imaging system is initially validated by imaging simple cylindrical targets and finally utilized for imaging defects in different tree trunk samples. Preliminary experimental results demonstrate the practicality, novelty and benefits of this approach for forestry imaging applications. INDEX TERMS.

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“…Due to its good spatiotemporal focusing property in complicated environments, the time reversal (TR) technique has been widely used in detecting and imaging applications, such as medical imaging [10,11], microwave imaging [12], radar imaging [13,14], and damage detection [15]. For the fundamental TR imaging technique, iterative time-reversal mirror (ITRM) imaging method works by iteratively retransmitting the back-scatterer signals and realizes the scatterer's positioning in the medium [16].…”

Section: Introductionmentioning

confidence: 99%

Resolution-Enhanced and Accurate Cascade Time-Reversal Operator Decomposition (C-DORT) Approach for Positioning Radiated Passive Intermodulation Sources

et al. 2023

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Attaining a high-resolution and accurate location for a radiated passive intermodulation source (R-PIMS) has been an increasingly interesting problem in modern multi-carrier wireless communication systems. For precisely positioning multiple closely spaced R-PIMSs, a novel imaging method called cascade decomposition of time-reversal operator (C-DORT) was developed. C-DORT constructs a new spectrum calculation by normalizing and multiplying the pseudo-spectrum at each sampled frequency together. The cascade process focuses the pseudo-spectrum at R-PIMS positions to form a highly brightened spectrum peak and to suppress the remained pseudo-spectrum to approximately zero, contributing to distinguishing the closely spaced R-PIMSs. The positioning performance of the positioning resolution, pseudo-spectrum width, positioning accuracy, and imaging robustness are analyzed by numerical simulations. Compared with the conventional central frequency decomposition of time-reversal operator (CF-DORT) and the time domain decomposition of time-reversal operator (TD-DORT) methods, the multiple R-PIMSs, spaced at a distance of diffraction limit, which is the spacing of 1/2 of a wavelength, are distinguished effectively in C-DORT. Additionally, the cross-range pseudo-spectrum full width at half maxima (CRPS-FWHM) is suppressed to the width of 1/4 of a wavelength by multiplication to improve the cross-range resolution in C-DORT. In addition, accurate positioning is obtained by providing the approximately zero positioning root mean square estimation (RMSE) at an SNR ranging from 0 dB to 10 dB. The results show that the proposed C-DORT improves the positioning accuracy and enhances the positioning resolution for locating an R-PIMS.

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A Microwave Time Reversal Algorithm for Imaging Extended Defects in Dielectric Composites

Cited by 7 publications

References 49 publications

Microwave time reversal for nondestructive testing of buried small damage in composite materials

Microwave time reversal for nondestructive testing of buried small damage in composite materials

A Microwave Tomography System Using Time-Reversal Imaging for Forestry Applications

Resolution-Enhanced and Accurate Cascade Time-Reversal Operator Decomposition (C-DORT) Approach for Positioning Radiated Passive Intermodulation Sources

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