• Title, Summary, Keyword: Dipole

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Radiation Characteristics of Log-Periodic Bent Dipole Antennas (대수주기 벤트 다이폴 안테나의 복사특성)

  • 최학근;김선표;임성빈
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.11
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    • pp.1207-1215
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    • 2003
  • In this paper Log-Periodic Bent Dipole Antenna(LPBDA), which is composed of bent dipole elements instead of dipole elements, is proposed to reduce the size of Log-Periodic Dipole Antenna(LPDA). LPBDA for the operating frequency band of 1 ㎓∼3 ㎓ is designed and its radiation characteristics are analyzed by the moment method, and compared with radiation characteristics of LPDA. It is shown that although LPBDA decreases in size by about 20 %, radiation characteristics of LPBDA are similar to radiation characteristics of LPDA. Calculated results show good agreement with measured results.

Near Fields around Metallic Walls due to a Nearby Dipole Source with Applications to EMC

  • Kim, Ki-Chai;Lim, Sung Min;Kim, Jong-Woo
    • Journal of Electrical Engineering and Technology
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    • v.12 no.1
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    • pp.329-334
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    • 2017
  • This paper discusses the near field characteristics of a dipole source located near conducting metallic walls from an electromagnetic compatibility (EMC) point of view. An integral equation for a dipole source near a metallic wall is derived and solved by applying Galerkin's method of moments (MoM). The results show that in the regions outside the dipole source, total electric near fields decrease gradually in magnitude with an increasing field point from the dipole source. But in the regions inside the dipole source, total electric near fields decrease rapidly with a dipole position of $h{\leq}0.3{\lambda}$. For a dipole position of $h{\geq}0.7{\lambda}$, the peaks and nulls of the total near electric field occur periodically in the regions inside the dipole source, and the fluctuation period is almost $0.5{\lambda}$. The worst position for a receptor location is along the z-axis, and a range of a half-magnitude of the maximum near electric field in the principal H-plane is about two times broader than that of the principal E-plane. Experimental measurements are also presented to validate the theory.

Radiation Characteristics of Log Periodic Cantor Koch Dipole Antennas (대수 주기 칸토어 코흐 다이폴 안테나의 복사 특성)

  • Park, Jae-Sung;Choi, Hak-Keun;Park, Jae-Hyun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.9
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    • pp.1005-1012
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    • 2010
  • In this paper, a novel log periodic cantor koch dipole antenna(LPCKDA), which is composed of the cantor Koch dipole elements instead of the Koch dipole elements, is proposed to reduce the size of the log periodic koch dipole antenna(LPKDA). To investigate the reliability of the proposed antenna, the LPCKDA is designed and analyzed at 0.5~1.5 GHz and compared with the LPKDA(Log Periodic Koch Dipole Antenna) characteristic. It is shown that although the proposed LPCKDA has a decreases of 5 % in the length of the dipole elements, radiation characteristics of LPCKDA are similar to radiation characteristics of the LPKDA.

Study of Stability Analysis and Countermeasure Tunnel Portal Failure using Dipole-Dipole Investigation (쌍극자(Dipole-Dipole)탐사를 활용한 터널붕괴사면 조사 및 대책방안 제시 연구)

  • Baek, Yong;Rhee, Jong-Hyun;Koo, Ho-Bon;Bae, Gyu-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.493-498
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    • 2003
  • In case of slope failure by planted protection is constructed on the slope according to of the choice trend of a recently environmental-friendly countermeasure, there has a limitation about diagnosis and preparation of measure. Also, collapse of tunnel pithead department slope has maximum in construction and countermeasure method of construction choice unlike cut-slope. In this study, analyzed inside circumstance of slope using geophysical exploration for stability analysis and countermeasure inside presentation of tunnel pithead department slope which collapse happens. geophysical exploration used dipole(Dipole-Dipole) method that is based to distribution principle does specific resistance, goes side by side with on-the-spot observation and draws base strength parameter and executed stability analysis, and presented stabilization countermeasure inside of collapse slope on this. I wish to conduce in development and research for use technical development of geophysical exploration technique hereafter by executing geophysical exploration in road collapse spot applying through this study.

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Broadband Microstrip Antenna (광대역 마이크로스트립 안테나)

  • 홍재표
    • Journal of the Korea Industrial Information Systems Research
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    • v.4 no.4
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    • pp.111-116
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    • 1999
  • In this paper, the electromagnetically coupled microstrip dipole antenna by adapting one parasitic metal-strip(dipole) between the microstrip transmission line open end and the radiating microstrip dipole antenna is presented for the bandwidth improvement The microstrip dipole antenna is simulated using Ensemble 51 simulation package The effects of varying several physical parameters, such as the lengths of radiating dipole and parasitic dipole and the width of parasitic dipole are investigated The bandwidth behavior of the 3-layer optimum antenna is compared with that of 2-layer antenna without the parasitic dipole. Experimental result for the obtained broadband performance is presented and discussed.

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The Influence of the Number of Electrodes, the Position and Direction of a Single Dipole on the Relation Between S/N ratio and EEG Dipole Source Estimation Errors (뇌전위의 단일 쌍극자 모델에서 전극의 개수, 쌍극자의 위치 및 방향이 S/N과 쌍극자 추정 오차사이의 관계에 미치는 영향에 관한 시뮬레이션 연구)

  • 김동우;배병훈
    • Journal of Biomedical Engineering Research
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    • v.15 no.1
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    • pp.71-76
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    • 1994
  • In the source localization using single dipole model, the influence of the number of electrodes, the position and direction of a single dipole on the relation between S/W ratio and dipole parameter estimation errors is important. Monte Carlo simulation was used to investigate this influence. The forward problem was calculated using three spherical shell model, and dipole parameters were optimized by means of simplex method. As the number of electrodes became large, as the dipole went from midbrain to cortex, and as the direction of dipole changed from radial to tangential, the average and standard deviation of estimation errors became small.

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Estimation of Ground and Excited State Dipole Moments of Coumarin 450 by Solvatochromic Shift Method

  • Naik, L.R.;Math, N.N.
    • Journal of Photoscience
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    • v.12 no.2
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    • pp.57-61
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    • 2005
  • The ground and excited state dipole moments of Coumarin 450 (C 450) laser dye were measured at room temperature in several solvents of varying dipole moments. The ground state dipole moment (${\mu}_g$) is estimated by using the modified Onsagar model and the excited state dipole moments (${\mu}_e$) were estimated by the method of solvatochromism as well as by utilizing the microscopic solvent polarity parameter ($E^N_T$). Further, the deviation of some of the points from the linearity of the $E^N_T$ versus Stokes shift indicates the existence of specific type of solute-solvent interaction. The excited state dipole moment of C 450 were found to be higher than those of the ground state and is interpreted in terms of the resonance structure of the molecule. A reasonable agreement has been observed between the values obtained by the method of solvatochromism and modified Onsagar model. It is observed that, corresponding to cyclohexane solution, the fluorescence maxima shift towards the red region with increasing the polarity of the solvents, hence the transition involved are of ${\pi}-{\pi}^*$ type.

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Modeling of a Scan Type Magnetic Camera Image Using the Improved Dipole Model

  • Hwang Ji-Seong;Lee Jin-Yi
    • Journal of Mechanical Science and Technology
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    • v.20 no.10
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    • pp.1691-1701
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    • 2006
  • The scan type magnetic camera is proposed to improve the limited spatial resolution due to the size of the packaged magnetic sensor. An image of the scan type magnetic camera, ${\partial}B/{\partial}x$ image, is useful for extracting the crack information of a specimen under a large inclined mag netic field distribution due to the poles of magnetizer. The ${\partial}B/{\partial}x$ images of the cracks of different shapes and sizes are calculated by using the improved dipole model proposed in this paper. The improved dipole model uses small divided dipole models, the rotation and relocation of each dipole model and the principle of superposition. Also for a low carbon steel specimen, the experimental results of nondestructive testing obtained by using multiple cracks are compared with the modeling results to verify the effectiveness of ${\partial}B/{\partial}x$ modeling. The improved dipole model can be used to simulate the LMF and ${\partial}B/{\partial}x$ image of a specimen with complex cracks, and to evaluate the cracks quantitatively using magnetic flux leakage testing.

Design for Dual Polarization Antenna Element using Electromagnetic-Coupled Dipole (전자결합 다이폴을 이용한 편파공용 안테나 소자의 설계)

  • ;;;;;;Hiroyuki Arai
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.128-131
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    • 2000
  • This paper describes design for dual-linear polarization antenna using EMC(electromagnetic-coupled) dipole. EMC dipole has a simple element structure and it is fed by microstrip line. Vortical and horizontal polarization are determined by structure of dipole fed by microstrip line. FDTD Method is used for an analysis of antenna element. Length, width, height and offset of dipole are designed for 1-element antenna. Resonant length of diploe differs from the calculated value by a formula because of coupling effect of dipole and feed line. Radiation Power is controlled by the offset of dipole. In prectical fabrication of antenna array, a constant height of dipoles is required. Therefore, the teflon plate with height of 0.8 mm is considered in antenna element design for the vertical polarization.

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