• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.5
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• pp.391-399
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• 2017

At present the general trend of modern electronics is toward smaller packages and high performance. As an antenna requires high powers, the EMC(Electromagnetic Compatibility) problems of the transmission line stage is becoming crucial day by day. In this paper, a transmission line excited by the electromagnetic fields from an infinitesimal electric dipole antenna is analyzed using the modified telegrapher's equations. The analytical equations are derived for arbitrarily positioned electric dipole with reference to a transmission line. To verify our approach, the induced voltage and current at the terminal were computed by the proposed approach and compared with those obtained by the electromagnetic simulation solver. Furthermore, the induced currents at the terminal of a transmission line excited by the electric dipoles at various positions were investigated using our approach.

• Journal of IKEEE
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• v.11 no.1 s.20
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• pp.61-68
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• 2007

Using modal transmission-line theory (MTLT), itexplores rigorously the polarization characteristics of TE-TM mode optical polarized beamsplitter with misaligned input interface. To verify the validity of the approach proposed in this paper, a novel polarization condition is defined, and it compares and evaluates with the polarization condition of coupled-mode theory (CMT) used widely. The numerical results reveal that the discontinuity of misaligned input interface has nothing to do with the polarization condition of beamsplitter. Furthermore, the condition of CMT is no longer effective at the asymmetric guiding structures with strong power coupling.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.193.1-193.1
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• 2016

본 연구에서 개발된 새로운 유형의 마이크로파 대기압 플라즈마 공진기는 전송선로 이론을 기반으로 하여 임피던스 값을 $50{\varphi}$으로 설계함으로써 장비 자체에 구조적인 매칭이 이루어지도록 구성하였다. 안정적인 마이크로파 대기압 플라즈마 발생을 위해 컴퓨터 시뮬레이션(HFSS, High Frequency Structural Simulator)을 이용하여 공진기의 반사계수, 공명주파수, 급전점 그리고 전기장을 계산하였다. 전송선로의 이론에서 구한 급전점과 실제 제작한 마이크로파 대기압 플라즈마 공진기의 급전점 값이 큰 차이가 없음을 확인하였다. 이를 바탕으로 제작한 공진기는 급전점 5.6 mm에서 공명주파수는 0.89 GHz, 반사계수는 -37.5 dB임을 측정하였고 신호가 입사되는 정도는 90 % 이상인 것을 확인하였다. 공진기에서 발생된 플라즈마는 6 W의 정도의 저 전력으로 발생되었으며 기체유량과 인가전력에 따른 플라즈마의 기체온도를 측정하고 광 방출 특성을 고찰하였다. 실제 제작한 마이크로파 대기압 플라즈마 발생장치는 생의학적 응용을 포함한 여러 넓은 분야에서 활용될 전망이다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.4
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• pp.335-341
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• 1991

We derive the radiation field equation at the naar field region to analyse EMI by the rectangular horn antenna. The EMI loadk current calculated from the load current induced on the transmission line being close to the rectangular horn antenna using the field theory and the transmission line theory. We find the conditions minimizing the EMI from the load current transfer function of distance, frequency and impedances at sending and receiving end. The smaller sending end impedance, the larger EMI load current and the larger sending impedance, the smaller EMI load current.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.187-192
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• 2017

Rigorous longitudinal modal transmission-line theory (L-MTLT) is applied to analyze maximum power transfer in asymmetric grating-assisted directional couplers(A-GADC). By defining a coupling efficiency amenable to rigorous analytical solutions and interference between symmetric and asymmetric supermodes, the power exchange of TE modes as a function of propagation distance is numerically evaluated. The numerical result reveals that maximum power transfer occurs at a grating period ${\Lambda}_{eq}$, in which the insertion loss of supermodes is equal to each other. That is, it is generally different from conventional phase-matching condition of GADC. Furthermore, as the asymmetric profile of grating change to symmetrical profile, the coupling length decreases and the coupling efficiency for power transmission increases.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12A
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• pp.1136-1146
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• 2005

In this paper, the radiative electric field intensity due to the communication signal and conductive noise is calculated in overhead medium voltage power lines for power line communication. The input impedance is calculated by means of 2 port equivalent model of medium voltage power line network and basic transmission line theory. And then, currents is calculated by calculated input impedance and finally, the emissive electric field is calculated. The input impedance appears like a standing wave form with a fixed cycle because high reflection at the input terminal due to the characteristic impedance of medium voltage power line is very large. A calculated current and radiative electric field also appears like this form. From the measurement results, the measured results are very similar to the calculated results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.973-984
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• 1999

This paper presents a method of moments with the transmission line theory to analyze the sleeve dipole array antennas and analyses characteristics of that. There were several considerations for analysis of the method of moments. First, the method of moments were applied at both of the sleeve dipole elements and the coaxial line because the current flows on both of them. Second, the feed voltages of each sleeve dipole element were obtained by using a transmission line theory because the feeding structure is fed by coaxial line in series. Third, the series reactance between the coaxial line and the open side of the sleeve was considered as impedance loading on the antenna. The radiation patterns and current distributions from the numerical results were considered as variation of the feed distances and frequencies. To verify the validity of our method, 4 elements sleeve dipole array antennas with 1 λg distance were fabricated and measured, and then the measured radiation patterns were compared with the numerical results. The measured results were confirmed a good agreement with the numerical results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.237-243
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• 2008

This paper presents the backplane effects for two-wire transmission line with different line length crossing the rectangular aperture in an infinite ground backplane. The FDTD method is used to determine the characteristics of the backplane insertion loss and return loss of the transmission line in accordance with the transmission line spacing and additional wire lengths. The results show that the insertion gain is obtained for the narrow spacing of the transmission line and the insertion loss is appeared for the transmission line with the additional wire The measurements of return loss are performed to verify the theoretical analysis.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.5 no.3
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• pp.48-58
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• 1994

In this paper, a CLPDA (Crossed Log-Periodic Dipole Antenna) for EMI / EMC Measurement is presented, and is analyzed by Combining the moment method and the transmission line theory. The CLPDA has a broaddband characteristic. It is so important to achieve a impedance matching over op- erating frequency range that Twin-boom method is used at feed point. Here, the current distribution, input admittance, radiation pattern and gain are calculated. In practice CLPDA is fabricated. Calculated result for radiation pattern and gain are very closed to measured result.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2293-2294
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• 2008

전력 수요가 증가하고 사용자가 더 나은 서비스와 안정성 요구함에 따라 전력 계통에서의 과도현상에 많은 관심이 모아지고 있다. 본 논문은 Bewley의 격자도와 진행파 이론을 사용하여 전송선에서 전압이나 전류의 인가 시 발생하는 진행파를 분석하였다. 또한 MATLAB을 이용하여 격자도나 진행파 이론 보다 더 쉽게 과도현상을 분석하는 방법을 모색해보고 시각적으로 표현하고자 한다. 진행파는 전송선로의 고장이나 외란에 의해서도 큰 영향을 받으므로 계통의 안정성을 높이기 위해서는 전자기적 과도현상을 이해하는 것이 중요하다. MATLAB을 이용하여 진행파를 분석하는 프로그램을 작성해 보고 하나의 사례를 들어 과도현상을 시각적으로 나타내었다. 이것은 과도현상을 이해하는데 도움이 될 것이다.