Determination of electromagnetic source localization with factorization method

2021 ◽  
pp. 1-10
Author(s):  
Nuri Gokmen Karakiraz ◽  
Agah Oktay Ertay ◽  
Ersin Göse
Keyword(s):  
Integral Equation ◽  
Incident Angle ◽  
Near Field ◽  
Field Measurements ◽  
Factorization Method ◽  
Field Equations ◽  
Direct Sampling ◽  
Test Equation ◽  
Inverse Source Problems ◽  
Electromagnetic Source

Abstract The factorization method (FM) is an attractive qualitative inverse scattering technique for the detection of geometrical features of unknown objects. This method depends on the selection of regularization parameters slightingly and has low calculation necessities. The aim of this work is to present a near-field FM for inverse source problems that have many applications. A modified test equation is obtained by converting the far-field term to Hankel's function. A different method has been proposed by manipulating the asymptotic approximation of Hankel's function in order to obtain near-field equations with incident angle and distance parameters. The novelty of this study is an integral equation based on the FM, which consists of multifrequency sparse near-field electric field measurements. We proved that the solution of the proposed integral equation gives information about the location of scatterers. The proposed algorithm is validated with simulation results and the capabilities of the presented method are assessed with several frequency regions and sources. Additionally, the presented method is compared with the direct sampling method in order to understand the performance of the proposed approach over a given scenario. The developed FM provides accurate results for electromagnetic source problems.

scholarly journals Broadband transmission-line illusions based on transformation electromagnetic

2019 ◽  
Vol 6 ◽  
pp. 23
Author(s):  
Tsutomu Nagayama ◽  
Atsushi Sanada
Keyword(s):  
Transmission Line ◽  
Incident Angle ◽  
Near Field ◽  
Homogeneous Medium ◽  
Field Measurements ◽  
Dielectric Substrate ◽  
Frequency Range ◽  
Microwave Frequencies ◽  
Intrinsic Nature ◽  
Line Technology

We demonstrate broadband transmission-line illusions based on transformation electromagnetics at microwave frequencies by using the distributed full-tensor anisotropic medium. Due to an intrinsic nature of the non-resonant unit cell of the medium, the illusions operate from DC to an upper limit frequency where the homogeneous medium approximation holds. Two-dimensional groove and bump illusion media mimicking scattered waves by an original groove and a bump are designed. Their broadband and incident angle independent operations are confirmed by circuit simulations. The groove illusion medium is implemented on a dielectric substrate with microstrip-line technology, and it is confirmed experimentally by near-field measurements that the illusion medium well mimics scattered waves by the original groove in the broadband frequency range from 2.60 GHz to 4.65 GHz.

Near-field Imaging Point-like Scatterers and Extended Elastic Solid in a Fluid

2016 ◽  
Vol 19 (5) ◽  
pp. 1317-1342
Author(s):  
Tao Yin ◽  
Guanghui Hu ◽  
Liwei Xu
Keyword(s):  
Near Field ◽  
Scattering Problem ◽  
Acoustic Scattering ◽  
Elastic Solid ◽  
Field Measurements ◽  
Factorization Method ◽  
Music Algorithm ◽  
Incident Wavelength ◽  
Imaging Point ◽  
Necessary And Sufficient

AbstractConsider the time-harmonic acoustic scattering from an extended elastic body surrounded by a finite number of point-like obstacles in a fluid. We assume point source waves are emitted from arrayed transducers and the signals of scattered near-field data are recorded by receivers not far away from the scatterers (compared to the incident wavelength). The forward scattering can be modeled as an interaction problem between acoustic and elastic waves together with a multiple scattering problem between the extend solid and point scatterers. We prove a necessary and sufficient condition that can be used simultaneously to recover the shape of the extended elastic solid and to locate the positions of point scatterers. The essential ingredient in our analysis is the outgoing-to-incoming (OtI) operator applied to the resulting near-field response matrix (or operator). In the first part, we justify the MUSIC algorithm for locating point scatterers from near-field measurements. In the second part, we apply the factorization method, the continuous analogue of MUSIC, to the two-scale scattering problem for determining both extended and point scatterers. Numerical examples in 2D are demonstrated to show the validity and accuracy of our inversion algorithms.

scholarly journals Imaging of bi-anisotropic periodic structures from electromagnetic near-field data

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Dinh-Liem Nguyen ◽  
Trung Truong
Keyword(s):  
Inverse Scattering ◽  
Maxwell Equations ◽  
Field Data ◽  
Periodic Structures ◽  
Near Field ◽  
Scattering Problem ◽  
Three Dimensional ◽  
Inverse Scattering Problem ◽  
Factorization Method ◽  
Unique Determination

AbstractThis paper is concerned with the inverse scattering problem for the three-dimensional Maxwell equations in bi-anisotropic periodic structures. The inverse scattering problem aims to determine the shape of bi-anisotropic periodic scatterers from electromagnetic near-field data at a fixed frequency. The factorization method is studied as an analytical and numerical tool for solving the inverse problem. We provide a rigorous justification of the factorization method which results in the unique determination and a fast imaging algorithm for the periodic scatterer. Numerical examples for imaging three-dimensional periodic structures are presented to examine the efficiency of the method.

scholarly journals Efficient Planar Near-field Measurements for Radiation Pattern Evaluation by a Warping Strategy

IEEE Access ◽  
2021 ◽  
pp. 1-1
Author(s):  
Maria Antonia Maisto ◽  
Giovanni Leone ◽  
Adriana Brancaccio ◽  
Raffaele Solimene
Keyword(s):  
Radiation Pattern ◽  
Near Field ◽  
Field Measurements
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