Optimum Two-Dimensional Uniform Spatial Sampling for Microwave SAR-Based NDE Imaging Systems

Case, Joseph T.; Ghasr, Mohammad Tayeb; Zoughi, R.

doi:10.1109/tim.2011.2169177

Cited by 89 publications

(46 citation statements)

References 10 publications

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“…In the SAR images, white indicated the presence of a strong return where black indicated the absence of a return. The SAR algorithm also subtracted the spatial average of all the measurement points [14]. The average was approximately the value of the metal plate below the sample, because the overall scan area was much greater than the size of the targets in the sample.…”

Section: B Sample 1: Targets On Foam Postsmentioning

confidence: 99%

“…For NDT&E applications in particular, synthetic aperture radar (SAR) imaging algorithms (based on backpropagation methods), capable of producing high spatial resolution images of objects and structures, have been extensively incorporated into a number of imaging systems including those with real-time image production capabilities [14]- [17]. To produce a SAR image, commonly one needs to measure vector (magnitude and phase) scattered field distribution over a known 1-D or 2-D grid.…”

Section: Introductionmentioning

confidence: 99%

“…For imaging purposes, one-way (transmission-through [16]) or two-way (one-sided mono-or bistatic [14]) measurements should be made at spatial intervals of less than or equal to λ/2 and λ/4, respectively. For the latter case in particular and when considering a collector array, this requirement imposes a severe restriction on the distance between the array elements.…”

Section: Introductionmentioning

confidence: 99%

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Wideband Imaging Array Using Orthogonally Fed Dual Varactor-Loaded Elliptical Slots

Baumgartner

Ghasr

Zoughi

2015

IEEE Trans. Instrum. Meas.

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Recent advances in several technological fronts have made it possible to design and develop real-time microwave imaging systems (cameras) for use in a wide range of applications. Proper design of the individual antenna array element in these systems is of critical importance. Furthermore, wideband versions of these imaging systems, which are capable of one-sided operation and in conjunction with advanced synthetic aperture radar imaging algorithms, can produce high-resolution 3-D holographical images. In this paper, an orthogonally fed, small elliptical dual varactor-loaded slot antenna, operating in K-band (18-26.5 GHz), is designed for use in such imaging systems. The feed design uses a coplanar waveguide with a 90°bend without a direct dc connection to the antenna. This feed structure accommodates effective placement of required switches while enabling one-sided measurement. Finally, the slot is loaded with two varactor diodes resulting in 3.5 GHz of bandwidth suitable for high-resolution microwave 3-D holographical imaging. The design of this slot and a (1/4) array of such slots is presented. Two arrays are fabricated and used independently, as well as simultaneously, to form (mono-and bistatic, respectively) imaging results.Index Terms-Antenna array feeds, antenna arrays, microwave imaging, millimeter wave imaging, nondestructive testing (NDT), synthetic aperture imaging.

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Section: B Sample 1: Targets On Foam Postsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Wideband Imaging Array Using Orthogonally Fed Dual Varactor-Loaded Elliptical Slots

Baumgartner

Ghasr

Zoughi

2015

IEEE Trans. Instrum. Meas.

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“…Then, a forward SAR transform computes the high-resolution, uniformly-spaced volumetric image s(x, y, z) from F(k x , k y , ω) by the NUFFT-based SAR algorithm [9][10][11] s(x, y, z) = F −1…”

Section: Cs Algorithms For 3d Sarmentioning

confidence: 99%

“…Although the NUFFT-based SAR algorithms have been shown to achieve higher accuracy with slightly higher computational complexity than the Stolt interpolation [9][10][11][12], we discover that utilising both NUFFT and inverse NUFFT in each CS iteration results in significant errors because of an inherent truncation window implied in the inverse NUFFT of the forward SAR. If not compensated, the error is accumulated via NUFFT in the R-SAR in each iteration of the CS, and it results in non-convergence of the CS algorithm for reconstruction of high resolution volumetric images.…”

Section: Introductionmentioning

confidence: 98%

Compressed sensing for SAR‐based wideband three‐dimensional microwave imaging system using non‐uniform fast Fourier transform

Kajbaf

Case

Yang

et al. 2013

IET Radar, Sonar & Navigation

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A new compressed sensing (CS) image reconstruction method is proposed for high-resolution wideband threedimensional synthetic aperture radar (SAR) imaging systems. In contrast to existing CS SAR methods that employ only a forward SAR transform in pre-or post-processing, the proposed method employs both forward SAR and reverse SAR (R-SAR) transforms in each CS iteration to improve the quality of reconstructed images. This study proposes a simple and elegant truncation repair method to combat the truncation error and utilises non-uniform fast Fourier transform to reduce the SAR and R-SAR transform errors, thereby ensuring the convergence of the CS algorithm and improving the quality of the reconstructed images. The proposed CS SAR method is applied to microwave and millimeter wave imaging systems for non-destructive evaluation of materials embedded in stratified media. Three different specimens under test are measured by conventional uniform sampling and by random under-sampling with 20% or 30% spatial points of the uniform sampling. The reconstructed images show that, albeit having much less measurement points, the proposed CS method achieves better image quality and lower background artefacts than the images reconstructed from the fullysampled uniform measurements.

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Literature Review

Moosazadeh¹

2019

Antipodal Vivaldi Antennas for Microwave Imaging of Construction Materials and Structures

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Optimum Two-Dimensional Uniform Spatial Sampling for Microwave SAR-Based NDE Imaging Systems

Cited by 89 publications

References 10 publications

Wideband Imaging Array Using Orthogonally Fed Dual Varactor-Loaded Elliptical Slots

Wideband Imaging Array Using Orthogonally Fed Dual Varactor-Loaded Elliptical Slots

Compressed sensing for SAR‐based wideband three‐dimensional microwave imaging system using non‐uniform fast Fourier transform

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