Microwave Subsurface Imaging Method by Incorporating Radar and Tomographic Approaches

Abstract

Due to its high resolution and deep penetration depth, microwave ultrawideband radar is a promising tool for the non-destructive testing (NDT) of transportation infrastructure. Microwave radiation can also be used to reconstruct the dielectric properties of objects and therefore can be used to detect an air cavity or metallic rust in concrete. We used contrast source inversion (CSI) as one of the most promising inverse scattering schemes. To resolve the observation domain limitations of nondestructive testing, radar imaging method, also known as range points migration (RPM) method, was first incorporated into the inverse scattering algorithm based on CSI as a region of interest (ROI) estimator, which substantially improves the accuracy of complex permittivity reconstruction. In addition, the ROI optimizing scheme based on the CSI cost function is used to enhance ROI accuracy. The effectiveness of the proposed methods is validated via finite-difference timedomain (FDTD)-based numerical simulation, which assumes typical NDT model.

Complex Permittivity Imaging by Incorporating Synthetic Aperture Radar and Inverse Scattering Method for Stratified Ground Medium

“…11 and 12, the accuracy of the radar image directly influences the reconstruction accuracy in the complex permittivity. While it is generally challenging to provide a complete estimate of the ROI using the radar image due to the limited spatial resolution or surface reflection effects from the ROI boundary, there are strategies to update the ROI using the CSI scheme as discussed in [27]. Nonetheless, the methods of providing the radar image as the ROI remains a critical issue and optimizing the inclusion of the ROI using the features of the inverse scattering method is an important future task.…”

“…This is because the illumination angle from the source is severely limited in the GPR model, and the number of observation data is much less than that of the unknowns. To address this issue, the radar prior-based CSI has been developed in [27]. This method drastically reduces the number of unknowns by limiting the ROI using a radar image.…”

“…However, the CSI suffers from the ill-posed feature, which is more severe in the GPR model due to the limited illumination angle. Some literature has introduced radar-image-based ROI restriction [27]- [32], where the ROI is focused on the area where the target exists. Nevertheless, the accuracy of the ROI is essential to determine the actual target area.…”

Frequency Diverse Array SAR With Fast-Time Space-Time Adaptive Processing for Subsurface Imaging

“…S UBSURFACE exploration is encountered in numerous applications [1]- [6], such as oil-field and ground-water determination in deserts, archaeological survey, planetary exploration and landmine detection. There are also many other applications including detection of landmines and underground facilities.…”

Simultaneous Exploitation of Multifrequency Data in Variable-Exponent Electromagnetic Imaging with Finite-Element Modeling

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Due to the uncountable number of potential applications, the mathematical solution of electromagnetic scattering problems has attracted the attention of researchers for decades. The scientific community is therefore very active in proposing novel solution methods, as well as strategies to make better use of all the available information, in the field of both forward and inverse scattering problems [1,2].

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