• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.1
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• pp.18-22
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• 2013

Input impedance of the inverted L antenna which is modified from a monopole antenna varies to very high input impedance value when the ratio of vertical height to horizontal length is reduced. So its impedance matching becomes very difficult. In this paper, we analyzed the input impedance variation range depending on the ratio of vertical height to horizontal length in the normal and ferrite thin film added configuration for the input impedance control. For the exact analysis involving the permittivity, permeability and conductivity of ferrite material, FDTD numerical method is used.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2004.12a
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• pp.43-51
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• 2004

Input impedance of the inverted L antenna which is modified from a monopole antenna varies to very high input impedance value when the ration of vertical height to horizontal length is reduced. So its impedance matching becomes very difficult. In this paper, we analyzed the input impedance variation range depending on the ratio of vertical height to horizontal length in the normal and ferrite thin film added configuration for the input impedance control. For the exact analysis involving the permittivity, permeability and conductivity of ferrite material, FDTD numerical method is used.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.9
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• pp.47-53
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• 2011

The signal transmission properties of the connector such as insertion loss and return loss are investigated using analysis procedure of S-parameter simulation, equivalent model extraction, and characteristic impedance calculation. S-parameter simulation is performed by connector's modeling and solving based on 3-dimensional finite element method. The connector's equivalent model of ${\pi}$ type is are proposed and extracted with an optimization process of circuit analysis simulator. The characteristic impedance of the connector is calculated with results of circuit analysis simulation and S-parameter data. According to the connector's characteristic impedance, it's revised design is carried out. In this work, the connector's effective contact area is increased and its body is applied as a high dielectric material in order to increase its capacitance and then obtain impedance matching. Therefore, return loss of the connector is improved by approximately 10 dB due to its design revision.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.11
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• pp.1034-1046
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• 2013

In this paper, a design of a GaN HEMT power amplifier using output matching circuit with arbitrary harmonic impedances is presented. The adopted GaN HEMT device, TGF2023-02 of TriQuint Semiconductor, was packaged in commercial package. The optimal impedances of the GaN HEMT package are extracted from load-pull simulation at package input and output reference planes. The targets of load-pull simulation are the highest output power at fundamental frequency and the highest efficiency at $2^{nd}$ and $3^{rd}$ harmonic frequencies. Because of fixture in the package, the extracted impedances shows arbitrary harmonic impedances. In order to match the optimal impedances, output matchin circuit which has 4 transmission lines is presented. Characteristic impedances and electrical lengths of the transmission lines are mathmatically calculated. The power amplfiier with $54.6{\times}40mm^2$ shows the output power of 8 W at the fundamental frequency of 2.5 GHz, the efficiency above 55 %, and harmonic suppression of above 35 dBc at the $2^{nd}$ and the $3^{rd}$ harmonics.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.2
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• pp.118-124
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• 2015

The design of radar absorbing structures(RAS) is a discrete optimization problem and is usually processed by stochastic optimization methods. The calculation of radar cross section(RCS) should be decreased to improve the efficiency of designing RAS. In this paper, an efficient method using impedance matching is studied to design RAS for minimizing RCS. Input impedance of the minimal RCS for the specified wave incident conditions is obtained by interlocking physical optics(PO) and optimizations. Complex permittivity and thickness of RAS are designed to satisfy the calculated input impedance by a discrete optimization. The results reveal that the studied method attains the same results as stochastic optimization which have to conduct numerous RCS analysis. The efficiency of designing RAS can be enhanced by reducing the calculation of RCS.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.3
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• pp.283-291
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• 2015

In this paper, a negative impedance converter, the key element of non-Foster matching to enhance the bandwidth of matching high Q-factor passive element, is presented. Proposed negative impedance converter is implemented by the topology of Linvill's transistor negative impedance converter circuit. It is hard to forecast the operation of negative impedance circuit, because it is composed of gain element and positive feedback. Therefore the negative impedance circuit is implemented by hybrid type beforehand to check out the feasibility and it is designed by integrated circuit. The integrated circuit is fabricated by commercial $0.18{\mu}m$ SiGe BiCMOS process, and non-Foster matching is observed at 700~960 MHz band by cancelling the target reactance.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.2
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• pp.213-219
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• 2012

In this paper, we suggested the method of signal integrity for noises and distortion signal generated between high speed information transmission modules by external effects. Suggested method for signal integrity of impedance matching to remove transmission line distortion, We divided the impedance matching between the transmitter and the receiver module with the single line and differential line methods after confirmed the improvement of signal distortions through ADS simulation. the experimental results indicated that it is possible to keep signal integrity without signal distortions by matching the optimal termination impedance which are considering the signal delay of transmission line for using the high-performance modules.

• Proceedings of the KAIS Fall Conference
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• 2002.11a
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• pp.197-200
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• 2002

본 논문에서는 IMT-2000용 AB급 대전력 증폭기를 설계 및 제작하였다. 전력증폭기의 주파수 대역은 IMT-2000용 순방향 주파수인 2110MHz-2170MHz에서 AB급으로 동작하도록 하였고, 고효율성과 우수한 선형성 소자인 LDMOSFET를 사용하였다. 설계 특성에 맞는 최적부하를 찾아 마이크로 스트립 회로로 입력 및 출력 정합 회로를 구현하였다 임피던스 정합 방법으로는 소자를 실제 측정상태에서 입력단과 출력단에 튜너를 삽입하고 기본 주파수에서 최대 출력상태를 만족하는 임피던스를 튜너로 구현한 후, 튜너를 제거하고 튜너의 입력 임피던스를 Network Analyzer로 측정하여 최적 부하 임피던스를 추출하는 로드풀 방법을 사용하였다. 대전력 증폭기의 측정결과로는 2-톤 인가시 40.57dBm의 출력결과를 얻을 수 있었고 30.61dBc의 상호 혼변조 특성을 확인하였으며, 원신호의 하모닉(Hamonic) 주파수 성분과는 21.46dBc의 차이를 보였다.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.328-332
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• 2000

본 논문에서는 기생 패치 구조와 적층 구조의 광대역 마이크로스트립 안테나에 평행 결합 선로 형태의 광대역 임피던스 정합 회로를 결합하여 쉽게 추가적인 임피던스 대역폭 개선을 얻을 수 있음을 제안하였다. 평행 결합 선로 형태의 광대역 임피던스 정합 회로 설계를 위하여 분포 회로 방식의 반복적인 방법을 제시하였고. 설계\ulcorner제작 결과 기생 패치 구조와 적층 구조에서 각각 56.23%와 16.45%의 추가적인 임피던스 대역폭 개선을 이룰 수 있었다. 그리고 방사 패턴과 측정된 이득을 보면 평행 결합 선로의 결합으로 인한 방사 패턴에서의 큰 변화는 보이지 않았고, 이득에서는 평행 결합 선로 부분의 커플링 손실로 인해 최대 이득이 약 1 dB 정도 감소하는 것을 확인할 수 있었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1148-1157
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• 2013

In a passive UHF RFID system, the impedance matching between tag antenna and chip as well as the protocol parameter settings in a reader plays important role in determination of the maximum read-range. Almost no paper, however, has dealt with the above issues in relation with the maximum read range. In this paper, two known methods (of using the value from data sheets and proprietary RFID tester) and our proposing method in chip impedance evaluation are compared in terms of maximum read range. The read range of tags whose antenna impedance is conjugate matched with the chip impedance obtained from the proposed method is improved maximum 73 % more than that of tags from the other methods.