• 한국컴퓨터정보학회논문지
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• 제27권2호
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• pp.135-144
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• 2022

전자기 토폴로지 기법은 복합적인 전파 환경의 모델링을 효과적으로 수행하기 위하여, 구성되는 전파 환경 단위를 각각 해석하고 네트워크의 형태로 결합하여 재해석하는 방법이다. 일반적인 상용 통신 채널 모델에서는 전파 환경이 복합적이고 예측이 어렵기 때문에 정확도는 낮지만 평균적인 해를 활용하는 확률 모델을 활용한다. 하지만, 상대적으로 높은 정확도의 전자파 전파 특성을 요구하는 전자기 펄스 등 위협 전자파의 전파 및 결합 분석, 전자전, 5G 및 6G 이상의 로컬 통신 채널 모델 등에 사용되는 전파 모델 응용에서는 전자기 토폴로지 기법을 활용한 전파 모델링 기법 등이 활용된다. 본 논문은 주파수 영역에서 해석되는 전자기 토폴로지(EMT) 기법의 효과적인 수행 방안과 알고리즘, 그리고 프로그램 구현에 대하여 설명한다. 또한 주파수 영역의 EMT 해석 결과에 대하여 임의의 인가 신호원에 대한 시간 영역에서의 응답을 도출하는 방안에 대하여 논의한다.

• 한국전자파학회논문지
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• 제23권6호
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• pp.716-722
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• 2012

본 논문에서는 WWAN 대역의 노트북 안테나와 LCD 구동 모듈 간의 전자기 간섭이 노트북의 무선 통신에 끼치는 영항을 분석하고, 이러한 간섭을 줄이기 위한 대책을 논의하였다. LCD 구동 모듈에 의한 잡음원을 모의하기 위해 다중 대역 안테나를 설계, 제작하였고, 이를 사용하여 노트북 내에서 전자기 간섭에 의한 효과를 시뮬레이션 및 모델 실험을 통해 분석하였다. 그 결과, 노트북의 구조에 기인한 특정 주파수 대역에서 더 많은 잡음이 전달될 수 있음을 확인하였다. 또한, 구조물 변화에 의한 잡음 전달의 감소를 위해 구조물에 격벽을 세우고, 그 크기를 변경하며 전자기 간섭을 분석하였으며, 이러한 구조 변경이 통신 대역 내의 전자기 간섭을 감소시킬 수 있음을 보여주었다.

• 한국정보기술학회 영문논문지
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• 제10권1호
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• pp.37-43
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• 2020

This paper presents analysis of passive metal interconnection of the LNA block in CMOS integrated circuit. The performance of circuit is affected by the geometry of RF signal path. To investigate the effect of interconnection lines, a cascode LNA is designed, and circuit simulations with full-wave electromagnetic (EM) simulations are executed for different positions of a component. As the results, the position of an external capacitor (C_ex) changes the parasitic capacitance of electric coupling; the placement of component affects the circuit performance. This analysis of interconnection line is helpful to analyze the amount of electromagnetic coupling between the lines, and useful to choose the signal path in the layout design. The target of this work is the RF LNA enabling the seamless connection of wireless data network and the following standards have to be supported in multi-band (WCDMA: 2.11~ 2.17 GHz, CDMA200 1x : 1.84~1.87 GHz, WiBro : 2.3~2.4GHz) mobile application. This work has been simulated and verified by Cadence spectre RF tool and Ansoft HFSS. And also, this work has been implemented in a 0.13um RF CMOS technology process.

• Journal of electromagnetic engineering and science
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• 제18권1호
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• pp.46-51
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• 2018

In this paper, a planar printed hybrid short/open-ended slot antenna with capacitive coupling feed strips is proposed for hepta-band mobile applications. The proposed antenna is comprised of a slotted ground plane on the top plane and two capacitive coupling feed strips with a chip inductor on the bottom plane. At the low frequency band, the short-ended long slot fed by strip 1 generates its half-wavelength resonance mode, whereas the T-shaped open ended slot fed by strip 2 generates its quarter-wavelength resonance mode for the high frequency band. The antenna provides a wide bandwidth covering GSM850/GSM900/DCS/PCS/UMTS/LTE2300/LTE2500 operation bands. Moreover, the antenna occupies a small volume of $15mm{\times}50mm{\times}1mm$. The operating principle of the proposed antenna and the simulation/measurement results are presented and discussed.

• Journal of electromagnetic engineering and science
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• 제15권3호
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• pp.194-198
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• 2015

Magnetic resonant coupling is more efficient than inductive coupling for transferring power wirelessly over a distance. However, a conventional resonant wireless power transfer (WPT) system requires a transmitter and receiver pair in exactly coaxial positions. We propose a resonator that can serve as an omnidirectional WPT system. A magnetic field will be generated by the current flowed through the transmitter. This magnetic field radiates omnidirectionally in the x-y plane because of the crisscross structure characteristic of the transmitter. The proposed resonator is demonstrated by using a single port. To check the received S21 and transfer efficiency, we moved the receiver around the transmitter at different distances (50-350 mm). As a result, the transmission efficiency is found to be 48%-54% at 200 mm.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.293-296
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• 2002

In this paper, we proposed a beam tilting microstrip patch array antenna for the reception of satellite signals by using low cost copper etched polyester films and foams. The configuration and coupling mechanism of the proposed antenna are similar to the dipole Yagi-Uda antenna. It is composed of 3 layers of polyester films and three layers of foam. In order to prevent unwanted radiation and coupling loss by microstrip feeding networks and parasitic patches, a stacked layer with rectangular slots above the driver patch array is inserted. The 16${\times}$8 element microstrip Patch way antenna is Presented by experimental results. Its beam patterns are affected by many parameters such as sizes of the patches, gap between the patches. characteristics of the substrates, feeding method, etc. Owing to its complexities of various design parameters, both simulation and experiment were performed. The fabricated antenna received DBS signal from KOREASAT 3 by doing nothing but adjusting azimuth direction.

• Journal of electromagnetic engineering and science
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• 제15권4호
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• pp.239-244
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• 2015

A simple planar heptaband antenna with a coupling feed for 4G mobile applications is proposed. This antenna consists of a folded monopole and a feed strip line on the top plane and an L-shaped line with a coupling plate on the bottom plane. The antenna provides a wide bandwidth to cover the LTE/GSM/UMTS heptaband operation. The measured 6-dB return loss bandwidth is 152 MHz (820-972 MHz) in the lowfrequency band and 1,150 MHz (1,600-2,750 MHz) in the high-frequency band. The overall dimensions of the proposed antenna are $60mm{\times}105mm{\times}1.2mm$.

• 전기전자학회논문지
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• 제22권3호
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• pp.846-849
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• 2018

Wireless power transfer (WPT) is the technology that enables the power to transmit electromagnetic field to an electrical load without the use of wires. There are two kinds of magnetic resonant coupling and inductive coupling ways transmitting from the source to the output load. Compared with microwave method for energy transfer over a long distance, the magnetic resonance method has the advantages of reducing the barrier of electromagnetic wave and enhancing the efficiency of power transmission. In this paper, the wireless power transfer circuit having a resonant frequency of 13.45 MHz for the low power system is studied, and the hardware implementation is accomplished to measure the power transmission efficiency for the distance between the transmitter and the receiver.

• Journal of electromagnetic engineering and science
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• 제8권4호
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• pp.144-147
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• 2008

This paper proposes a tunable combline bandpass filter with high selectivity, constant bandwidth, and good stopband performances. A filter with these characteristics is obtained by applying cross-coupling to the conventional combline bandpass filter using stepped-impedance resonators(SIRs). For high selectivity and constant bandwidth, cross-coupling is utilized and the SIR configuration is used for enhanced stopband performances. The proposed combline tunable bandpass filter with 5% of fractional bandwidth at 1.6 GHz was fabricated and tested. The measured results showed 11.6% tunability with constant bandwidth, high selectivity and enhanced stopband characteristics.

• Journal of electromagnetic engineering and science
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• 제13권4호
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• pp.240-244
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• 2013

In this paper, we present an improvement of a closed-form formula for mutual impedance computation. Depending on the center-to-center spacing between two rectangular microstrip patch antennas, the mutual impedance formula is separated into two parts. The formula based on synthetic asymptote and variable separation is utilized for spacings of more than 0.5 ${\lambda}_0$. When the spacing is less than 0.5 ${\lambda}_0$, an approximate formula is proposed to improve the computation for closely spaced elements. Simulation results are compared to computational results of mutual impedances and mutual coupling coefficients as functions of normalized center-to-center spacing in both E- and H-plane coupling configurations. A good agreement between simulation and computation is achieved.