• Title/Summary/Keyword: Dyadic Green's function

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Dyadic Green`s Function for an Unbounded Anisotropic Medium in Cylindrical Coordinates

  • Kai Li;Park, Seong-Ook;Pan, Wei-Yan
    • Journal of electromagnetic engineering and science
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    • v.1 no.1
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    • pp.54-59
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    • 2001
  • The dyadic Green`s function for an unbounded anisotropic medium is treated analytically in the Fourier domain. The Green`s function, which is expressed as a triple Fourier integral, can be next reduced to a double integral by performing the integral, by performing the integration over the longitudinal Fourier variable or the transverse Fourier variable. The singular behavior of Green`s is discussed for the general anisotropic case.

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Numerical Analysis of EM scattering by Underground Object for GPR application (지하물체 탐지를 위한 수치해석법 연구)

  • Kim, Sung-Hwan;Ahn, Chang-Hoi
    • Proceedings of the KIEE Conference
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    • 2007.07a
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    • pp.1506-1507
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    • 2007
  • For GPR applications, accurate analysis of the scatterered field is necessary to identify the unknown target. Dyadic Green's Function of the multilayered medium is developed and applied to analyse of underground conduting object. We used method of moment(MOM) with dyadic Green's function, and Discrete Complex Image Method(DCIM).

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An Approximate Closed Form Representation of the Microstrip Dyadic Surface Green's Function (Mictrostrip Dyadic 표면 Green 함수의 근사표현식)

  • 최익권
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.18 no.4
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    • pp.549-560
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    • 1993
  • A simple closed form approximation is developed by a new approach presented in this paper for the microstrip surface dyadic Green's function which arises in the problem of an electric current point source on an infinite planar grounded dielectric substrate. This closed form approximation includes the effects of the space wave, the surface wave and their coupling within the transition region near the source, and remains accurate as near as $0.1{\pi}_1$ from the source point for a substrate thickness as large as $0.04{\pi}_1$, where, ${\pi}_1$, is the free space wavelength, This result can significantly facilitate the rigorous moment method analysis of microstrip antenna arrays on relatively this substrates of practical interest. Numerical results illustrating the accuracy of the closed form approximation are presented and CPU times associated with some mutual impedance calculations are also included.

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The Effect of a High Temperature Superconducting Patch on a Rectangular Microstrip Antenna

  • Chebbara, Fouad;Amir, Mounir;Fortaki, Tarek
    • Journal of Electrical Engineering and Technology
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    • v.4 no.2
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    • pp.277-281
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    • 2009
  • The complex resonant frequency problem of a superconductor patch is formulated in terms of an integral equation which is the kernel of a dyadic Green's function. To include the effect of the superconductivity of the microstrip patch, the surface complex impedance of the superconductor film is introduced using the two fluids model of Gorter and Casimir. The Galerkin procedure is used in the resolution of the electric field integral equation. Numerical results concerning the effect of the operating temperature of a superconductor patch on the characteristics of the antenna are presented.

Numerical Experiments using Efficient FMM for the EM Scattering by Underground Object (지하물체 탐지를 위한 FMM 기반의 효율적인 수치 해석 연구)

  • Kim, Sung-Hwan;Ahn, Chang-Hoi
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.9
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    • pp.1790-1795
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    • 2009
  • For GPR(Ground Penetrating Radar) applications, an accurate analysis of the scattered field is necessary to identify the unknown target. Dyadic Green's function of the multilayered medium is developed and applied to analysis of the underground conducting object. We used method of moment(MOM) with dyadic Green's function, and Discrete Complex Image Method(DCIM). To reduce the computational complexity, fast multipole method is introduced and we showed the accuracy of the method comparing with the conventional method of moment. For investigating the underground conducting target, several numerical experiments were accomplished using this method.

Criterion to Choose Efficient Far-Field Approximation of Dyadic Green's Function for Impedance Plane like Ocean Surface (해수면 같은 임피던스 평면 위의 다이아딕 그린함수에 관한 효율적 원거리 근사공식 선택 기준)

  • Lee, Hyunsoo;Koh, Il-Suek;Yoon, Jong Suk;Kim, Tae Hyung
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.28 no.2
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    • pp.147-154
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    • 2017
  • The impedance approximation has been widely used to model an earth surface such as ocean surface. In calculation of the dyadic Green's function for the impedance half plane, Sommerfeld integral and its partial derivatives are required. It is known that two far-field approximation of the Sommerfeld integral can be represented in terms of Legendre or Laguerre polynomials. Hence, a criterion is required to choose one of two far-field approximations for a given application, which can be expressed in a complex plane of the surface impedance. Also, we approximate the required partial derivatives of Sommerfeld integral and numerically verify the accuracy of the approximation.

Improvement of the Convergence for the Green's Function in Three Layered Media (3층매질 Green함수의 수렴성 개선)

  • Hwang, Jae-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2007.10a
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    • pp.219-222
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    • 2007
  • The paper deals with the rigorous analysis of three layered media structures. The dyadic Green's function for three layer medium is derived. The Green's functions belonging to the kernel of the integral equation are expressed as Sommerfeld integrals, in which surface wave effects are automatically included. We propose this integral representation as the most appropriate in the spatial domain analysis of slive structure. Also, we used extraction method for the convergence of this integral function. Finally, some numerical results are presented. These computed value show good agreement with proposed this method.

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The Radiation Patterns of Bent Dipole Antennas (벤트 다이폴 안테나의 복사 패턴)

  • 강민호;문상진
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.19 no.2
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    • pp.7-13
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    • 1982
  • In this Paper, the radiation Patterns of long wire antennas are computed by applying Dyadic Green's Function to the propagation vector, This result is used to analyze the polarized radiation patterns for the various geometrical structures of the bent dipole antennas. When the ratio of the vertical portion over the total length of the bent dipole antenna is 0.4major angle and axail ratio are changed most sensitively for the azimuth rotation, and the radiation field propagates strongly perpendicular to the bent antenna plane.

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A Study on Varactor Tuning Gunn Oscillator for X Band (Varactor 튜닝 X 밴드 Gunn 발진기에 관한 연구)

  • 박한규;천장호
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.15 no.5
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    • pp.39-45
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    • 1978
  • This paper described on the varactor tuning Gunn oscillator for X band. Analyzed the coplanar 2 post case using the dyadic Green's function then derived the obstacle network for the incident TE10 mode. For the electronical tuning, used the tuning varactor diode which has a high speed dynamic response characteristic and high Q. Oscillation frequency, switching mode, and stable oscillation point were calculated by the computer simulation. In the expriments, switching mode was occurred at 18 mm, 32.5 mm of the short tcircuit position, respectively. The general characteristics of the varactor tuning Gunn oscillator were abruptly changed by the moving of the short circuit and the variation of the bias voltage.

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Analysis of Radiation Pattern of Antenna in Multi-Layered Media (다층매질 중 안테나의 방사패턴 해석)

  • Hwang, Jae-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2008.05a
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    • pp.677-680
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    • 2008
  • The paper deals with the analysis of radiation characteristics of antenna in the multi-layered media structures. The dyadic Green's function for three layer medium is complex because the Green's functions belonging to the kernel of the integral equation are expressed as Sommerfeld integrals, in which surface wave effects are automatically included. When certain condition are met, the integral can be evaluated approximated by the method of Saddle-point integration. In this study, we propose a method to calculate a radiation pattern for several antennas by using the method of Saddle-point integration. Numerical results show how the radiation characteristics are affected by parameter of dielectric media.

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