• Title/Summary/Keyword: Electromagnetic Scattering

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Scattering Model for Hard Target Embedded inside Forest Using Physics-based Channel Model Based on Fractal Trees (프랙탈 나무 모델을 이용한 숲 속에 숨어 있는 타겟의 산란모델)

  • Koh Il-Suek
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.2 s.93
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    • pp.174-181
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    • 2005
  • In this paper, a hybrid model is developed, which can estimate scattering properties of a target embedded inside a forest. The model uses a physic-based channel model for a forest to accurately calculate the penetrated field through a forest canopy. The channel model is based on a fractal tree geometry and single scattering theory. To calculate scattering from the target physical optics(PO) is used to compute an induced current on the target surface since the dimension of the target is generally very large and the shape is very complicated. Then using reciprocity theorem, scattering generated by the PO current is calculated without an extra computational complexity.

Analysis of Microwave Inverse Scattering Using the Broadband Electromagnetic waves (광대역 전자파를 이용한 역산란 해석 연구)

  • Lee, Jung-Hoon;Chung, Young-Seek
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2005.11a
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    • pp.169-174
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    • 2005
  • In this paper, we proposed a new algorithm of the inverse scattering for the reconstruction of unknown dielectric scatterers using the finite-difference time-domain method and the design sensitivity analysis. We introduced the design sensitivity analysis based on the gradient for the fast convergence of the reconstruction. By introducing the adjoint variable method for the efficient calculation, we derived the adjoint variable equation. As an optimal algorithm we used the steepest descent method and reconstructed the dielectric targets using the iterative estimation. To verify our algorithm we will show the numerical examples for the two-dimensional $TM^2$ cases.

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MOM-Based Born Iterative Method for Medical Microwave Imaging (의용 전자파 영상을 위한 MoM 기반 Born 반복법의 적용)

  • Son, Jae-Gi;Kim, Bo-Ra;Lee, Taek-Kyung;Son, Seong-Ho;Jeon, Soon-Ik;Lee, Jae-Wook
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.4
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    • pp.524-532
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    • 2012
  • In this paper, we used MOM-based BIM(Born Iterative Method) algorithm to implement the inverse scattering for the detection of cancer. We adopted two-dimensional breast structure, integral equations and two-dimensional Green's function is solved with MoM(Method of Moment) to analyzing electromagnetic scattering phenomena. In addition, verifying the calculation of developed inverse scattering algorithm and analyzing medical applicability and limitations of the algorithm.

The characteristics and optimization of submicron optical mask using electromagnetic scattering effect (전자기파 산란을 이용한 Submicron 광학 MASK의 특성 및 최적화)

  • 최준규;박정보;김유석;이성묵
    • Korean Journal of Optics and Photonics
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    • v.8 no.4
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    • pp.345-352
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    • 1997
  • Recently, in designing optical mask such as 4GDRAM, the scattering effect of electromagnetic wave must be considered. For this reason we claculated directly the mask function using the finite difference time domain(FDTD) method. The modification of image theory with this new mask function could explain clearly the scattering effect at the etched side wall of the submicron optical mask. The characteristics of the various type of alternating PSM were investigated. According to the simulation, the dual wet etch process was the most useful fabrication technique to overcoe the light scattering off at the shifted opening.

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A Study on the Synthesis of TE and TM Scattering Patterns of One-Dimensional Inhomogeneous Dielectric Media (일차원 비균질 유전매질의 TE 및 TM 산란패턴 합성에 관한 연구)

  • Nam, June-Seok;Jun, Sang-Jae;Jeon, Hoo-Dong;Jung, Jun-Sik;Park, Eui-Joon
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2003.11a
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    • pp.69-73
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    • 2003
  • In this paper, a synthesis method for the desired scattering pattern is presented when illuminating by TE-polarized and TM-polarized plane waves to arbitrary dielectric material. It is considered that the one-dimensional dielectric media are inhomogeneously distributed with continuously varying dielectric constants. Accordingly the desired patterns and the corresponding source distributions are inversely transformed by the proposed algorithm which are based on the one-dimensional inverse scattering problem. Some bandstop spatial filter are illustrated for applications.

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The Analysis of Scattering Characteristics of Raindrops and Estimation of Specific Rain Attenuation for Different Drop Shapes (빗방울의 형태에 따른 산란특성 해석 및 강우감쇄 계수 추정)

  • 황정환;백정기;김양수;김영민;최용석;이주환;박세경
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.10 no.5
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    • pp.701-710
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    • 1999
  • To predict rain attenuation accurately, we must know scattering characteristics of rain-drops for real drop shapes. In this paper, the scattering characteristics of rain-drops are analyzed by an analytical model, and the differences in the characteristics of the forward scattering amplitudes for three different rain-drop shapes are compared. Using the results for the Pruppacher-Pitter's real rain-drop shaper, the specific rain attenuation in domestic environment is predicted, and the difference from the ITU-R model is compared and analyzed.

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Analysis of E-polarized Electromagnetic Scattering by a Conductive Strip Grating Between a Double Dielectric Layer Using FGMM (FGMM을 이용한 2중 유전체층 사이의 완전도체띠 격자구조에 의한 E-분극 전자파 산란 해석)

  • Yoon, Uei-Joong
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.20 no.1
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    • pp.77-82
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    • 2020
  • In this paper, E-polarized electromagnetic scattering problems by a conductive strip grating between a double dielectric layer are analyzed by applying the FGMM(Fourier-Galerkin moment method) known as a numerical method of electromagnetic fileld. The boundary conditions are applied to obtain the unknown field coefficients, and the conductive boundary condition is applied to analysis of the conductive strip. The numerical results for the normalized reflected and transmitted power are analyzed by according as the width and spacing of conductive strip, the relative permittivity and thickness of the double dielectric layers, and incident angles. Generally, as the value of the dielectric constant of the double dielectric layer increases, the reflected power increases and the transmitted power decreases, respectively. As the dielectric constant of the double dielectric layer increases, the current density induced in the strip center increases. The numerical results for the presented structure of this paper are shown in good agreement compared to those of the existing papers.

Experimental Verification of Electromagnetic Cloak Based on Quasi-Conformal Mapping (준등각 맵핑 기반 전자기파 투명화 구조의 실험적 검증)

  • Kim, Yongjune;Seo, Ilsung;Koh, Il-Suek;Lee, Yongshik
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.6
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    • pp.491-494
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    • 2016
  • A design method is proposed to minimize the scattering cross section(SCS) of the electromagnetic cloak based on the quasi-conformal mapping. Often times in such cloaking structures, parts that require refractive index below one are approximated with free space because of the difficulty involved with realization. In this process, preformance degradation is inevitable. In this work, the size of the cloak is optimized to compensate for the deterioration, and thus to minimize the scattering cross section of a diamond shaped conductor. Proposed cloak is fabricated using a 3D printer, and verified by measuring the cloaking performance of a diamond shaped aluminum target.

Electromagnetic Scattering Resonances on a Periodic Strip Grating on a Grounded Dielectric Slab: Bragg Blazing Phenomena of TM Polarization Case (접지된 유전체 슬랩 위에 위치한 주기적인 스트립 격자구조에서의 전자기적 산란공진;TM편파 경우의 Bragg Blazing 현상)

  • 조웅희;홍재표;김종규;조영기
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.8
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    • pp.1363-1375
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    • 2000
  • The electromagnetic scattering characteristics by a periodic strip grating on a grounded dielectric slab for TM polarization case are examined from the viewpoints of both the reflection grating and the leaky wave antenna problems. Numerical results far two kinds of Bragg blazing (resonance type and non-resonance type) phenomena are given and some discussions on the properties(complex propagation constants, scattering characteristics, and distributions of strip current density) are presented. The comparison of the Bragg blazing phenomena between TM and TE polarization cases are also given in detail.

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Parametric Inverse Scattering for Lossless Dispersive Media with Enhanced Robustness

  • Park, Hyoung-Jin;Lee, Sang-Seol
    • Journal of electromagnetic engineering and science
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    • v.3 no.1
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    • pp.57-61
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    • 2003
  • The effects of high frequency noises on a perturbational inversion technique for a stratified dispersive medium are investigated in this paper. It is shown that the perturbational solution becomes unstable under high frequency noises. The physical origin of this instability is described. In order to enhance the robustness of the perturbational inverse scattering solution, a parametric inversion technique is introduced. The examples for the 2-pole and the 3-pole reflection coefficients are compared and contrasted, and improvement of the robustness of the solutions is shown.