Through a Cinder Block Wall Refocusing Using SAR Back Projection Method

Khorashadi-Zadeh, Vahid; Dehmollaian, Mojtaba

doi:10.1109/tap.2018.2882599

Cited by 9 publications

(8 citation statements)

References 25 publications

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“…The GF of the reinforced concrete wall is evaluated here in section 2.2. To remove artefacts from the image (Figure 5c), we use only the phase of the GF [19]. The new imaging formulation is…”

Section: Modified Back Projection Methods Using Proper Green's Functionmentioning

confidence: 99%

Two‐dimensional synthetic aperture imaging of targets behind reinforced concrete walls

Tayarani

Dehmollaian

2022

IET Radar Sonar & Navi

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Synthetic aperture imaging of targets closely behind a reinforced concrete wall, modelled by a periodic structure by using the proper Green's function (GF) of the structure, is studied. To compute the GF accurately, using the rigorous coupled‐wave analysis (RCWA) is proposed. The radiation of a line source in the spectral domain as a summation of plane waves is represented. Illuminating the periodic structure by each plane wave, Bragg modes by RCWA are computed. Then, the GF is estimated as the superposition of all the Bragg modes' contributions. The numerical Finite Element Method results of COMSOL validate the results of our semi‐analytical approach. Having COMSOL numerically calculated backscattered fields of a target behind the wall and the simple free‐space GF, the synthetic aperture image of a target is not focussed. Employing the phase of the proper GF instead of the simple free‐space GF, the target image is successfully refocussed. The effect of the number of Bragg modes on the estimation of the GF and also uncertainties in the distances between reinforced metallic bars on the target image is investigated.

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Section: Modified Back Projection Methods Using Proper Green's Functionmentioning

confidence: 99%

Two‐dimensional synthetic aperture imaging of targets behind reinforced concrete walls

Tayarani

Dehmollaian

2022

IET Radar Sonar & Navi

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“…1. Different to most of the known qualitative applications, where the antenna array is located on one side of the medium only (limited-angle) [6], [7], here, in order to determine the dielectric value, the antenna array is located at both sides of the foam (full-angle). The computational domain consist of the polymer foam of size 4,4] cm.…”

Section: Mwt Setupmentioning

confidence: 99%

A Combined Microwave Imaging Algorithm for Localization and Moisture Level Estimation in Multilayered Media

Omrani

Yadav

Link

et al. 2021

2021 15th European Conference on Antennas and Propagation (EuCAP)

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In this work, a multistatic uniform diffraction tomography (MUDT) method, that was proposed by the authors as a new qualitative imaging method just recently, is combined with the quantitative Bayesian inversion framework. In this combined approach, MUDT is applied to find the location of the moisture and this localization is employed as a pre-knowledge for the Bayesian framework to estimate the moisture levels in a polymer foam. The proposed combined algorithm might become a major part of the development of a new kind of intelligent industrial microwave drying systems. The imaging algorithm is tested with simulated measurement data. The frequency band from 8 GHz to 12 GHz (X-band) is used for the MUDT algorithm whereas a single frequency of 8.2 GHz is assumed for the Bayesian framework. The first results demonstrate the ability of the developed combined algorithm for optimizing the computational load unlike seen in the quantitative inversion approaches.

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“…The entropy method is used here to obtain the dielectric constant of the background cylinder. A similar procedure has been previously used to estimate the parameters of a wall in the throughthe-wall imaging application [37]. The optimal focused microwave images have been determined by the minimum entropy criterion before [38].…”

Section: Dyadic Green Function Of An Infinitely Long Dielectric Cylinmentioning

confidence: 99%

Localisation and permittivity extraction of an embedded cylinder using decomposition of the time reversal operator

Omrani

Moghadasi

Dehmollaian

2020

IET Microwaves, Antennas & Propagation

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In this study, first, the problem of time reversal imaging of an embedded dielectric or metallic cylinder inside another dielectric cylinder is studied. The direct problem is carried out numerically using the finite‐element method. The background dyadic Green function (DGF) is computed analytically by computing radiated fields of an infinitesimal electric dipole near an infinitely long dielectric cylinder. The time reversal technique is then applied using this background DGF to image the embedded cylinder. Results demonstrate that while using a free‐space DGF for imaging yields erroneous results, by employing a proper background DGF, the scatterer inside the cylinder is correctly localised. Next, the authors extract permittivities in two different scenarios with two different techniques. In the first case, the permittivity of a background cylinder that contains a metallic cylinder inside it is extracted by calculating the image entropy. In the second case, the permittivity of an embedded cylinder inside a priori known background dielectric cylinder is estimated by a new method based on an optimisation and evaluation of the largest eigenvalues of the multistatic data matrices. The proposed techniques are then verified using simulated and measured data. For measurements, a newly developed combined tapered sectorial antenna is designed, fabricated, and characterised.

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Through a Cinder Block Wall Refocusing Using SAR Back Projection Method

Cited by 9 publications

References 25 publications

Two‐dimensional synthetic aperture imaging of targets behind reinforced concrete walls

Two‐dimensional synthetic aperture imaging of targets behind reinforced concrete walls

A Combined Microwave Imaging Algorithm for Localization and Moisture Level Estimation in Multilayered Media

Localisation and permittivity extraction of an embedded cylinder using decomposition of the time reversal operator

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