• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.1
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• pp.90-97
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• 1992

An estimation method for the amplitude and phase response of transmission line is discussed. and applied to narrow band ISDN subscriber line. The ABCD parameters of line are evaluated from four impedance values: the standard termination impedence at activated and deactivated stares, and the input impedances of line which can be estimated at each state. Estimating input impedence, the “chirp” signal is used as incident signal and noise effect can be reduced by ensemble averaging. These ABCD parameter estimations might be applicable to ether uniform or nonuniform line. Cleary the magnitude and phase response can be obtained from estimated ABCD parameters. The numerical simulation results for N ISDN subscriber line model are included, and the estimation error introduced by deviation in load impedence is also anlyzed.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1981-1983
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• 2003

본 연구에서는 고속전력선통신(PLC)을 위한 고압배전선의 임피던스 측정 방법을 소개한다. 현재 전세계적으로 고속 PLC를 위해서 1MHz${\sim}$30MHz대역을 사용하고 있다. 임피던스 특성을 실제 필드에서 측정하기 위해 본 연구에서는 휴대용 고압결합장치를 개발하였다. 임의의 고압 배전선에 일시적으로 결합할 수 있도록 고안된 고압결합장치로서 살아있는 전력선에 정전 없이 설치 가능하다. 이 장치는 고압용 커풀러(Coupler)와 60Hz 저주파를 차단하기 위한 드레인 코일(drain coil)로 구성되었다. 측정을 위해서는 벡터 회로망 분석기를 사용하였으며, 본 논문에서는 측정된 고압선 임피던스를 보여 주고 이 결과를 이용한 임피던스 정합 방법을 제시하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.10
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• pp.2345-2350
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• 2014

In this paper, measurement methods for the characteristics of antennas for indoor digital TV (DTV), having 75-ohm port impedance, are introduced. Reference impedance of typical radio frequency (or microwave) systems and measurement equipments is 50 ohm. However, the reference impedance of antennas for indoor DTV is 75 ohm, and the characteristics of the antennas cannot be measured directly using the measurement equipments. Measurement methods, using test equipments with reference impedance of 50 ohm, for the characteristics(impedance, radiation patterns, and gain) of antennas designed to fit for 75 ohm port are introduced.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.45-46
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• 2014

In this paper, measurement methods for the characteristics of antennas for indoor digital TV (DTV), having 75-ohm port impedance, are introduced. Reference impedance of typical radio frequency (or microwave) systems and measurement equipments is 50 ohm. However, the reference impedance of antennas for indoor DTV is 75 ohm, and the characteristics of the antennas cannot be measured directly using the measurement equipments. Measurement methods, using test equipments with reference impedance of 50 ohm, for the characteristics(impedance, radiation patterns, and gains) of antennas designed to fit for 75 ohm port are introduced.

• The Journal of the Acoustical Society of Korea
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• v.28 no.4
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• pp.363-369
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• 2009

In this paper, an estimation method is presented to determine the equivalent circuit model of an underwater acoustic piezoelectric transducer with multiple resonant modes. A fitness function that includes the coupled resonant effects is proposed to minimize an error between the measured impedance of the transducer and the calculated impedance of the equivalent model. Unknown parameters of the equivalent circuit are estimated by using PSO algorithm. The proposed method is applied to an example transducer of the sandwich type with 3 resonances in the frequency band of interest. The analytical impedance of the estimated equivalent circuit model is compared with the measured impedance of the transducer and the validity of proposed method is verified.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.6 no.1
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• pp.35-41
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• 1986

A hybrid modelling technique of a soil-structure system on viscoelastic soil medium is studied in this paper. The hybrid model consists of a near-field and a far-field with their common interface passing through the soil region at some distance from the base of the structure. It makes use of frequency-dependent impedances so as to represent the semi-infinite far-field. The far-field impedances are formulate including the radiation damping characteristics as well as the viscoelastic properties of the soil medium. The verification of the method has been carried out using a rigid circular plate on a viscoelastic half-space. The impedances obtained by the method are compared with the theoretical values. Example analyses have been performed for a tall chimney and the results have been compared with those obtained by other methods which are frequently used.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.10
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• pp.1282-1289
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• 2019

In order to measure the transfer characteristic(S21) of the impedance transformer, two impedance transformers must be symmetrically connected. However, the transfer characteristic of two symmetrically connected impedance transformers is influenced by the length of the intermediate connection line. This paper theoretically examines closely the length of the intermediate connection line to obtain the accurate transfer characteristic of the impedance transformer. The electrical length of the intermediate connection line for obtaining the accurate transfer characteristic of the 4:1(50-Ω:12.5-Ω) impedance transformer is calculated about 45°. Using the calculated length of the connection line, The λ/4-microstrip impedance transformer is fabricated at 1 GHz to measure the transfer characteristic. The symmetrically connected impedance transformer is measured the reflection characteristic(S11) of -40.64dB and the transfer characteristic(S21) of -0.154dB at 0.980GHz. This value is approximately equal to the theoretical calculated 987MHz center frequency and -0.15dB transfer loss value of the λ/4-microstrip impedance transformer.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.47-53
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• 2013

In this work, signal transmission properties of SATA connector have been improved using its differential impedance calculation and its design revision to closer impedance matching. Using 3 dimensional electromagnetic field simulator, the differential mode S-parameter was calculated to investigate its signal fidelity. The differential impedance is calculated from the equation of the odd mode impedance with inductance, capacitance, mutual inductance, and mutual capacitance. The differential impedance of SATA connector was calculated to be $107.3{\Omega}$ and did not meet the design specification with $100{\Omega}{\pm}5%$. In order to achieve its impedance range and improve its signal transmission properties, SATA connector's design has been revised with two different directions and analyzed through the calculation of differential impedance, differential reflection loss, and differential insertion loss.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.4
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• pp.418-426
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• 2008

In this paper, investigations on the impedance characteristics of a DGS(Defected Ground Structure) slot in the groud plane of microstripline are presented in spectral domain and applied to the characteristic improvement of stepped impedance microstrip low pass filter(LPF). In this method, expressions for the impedance of a DGS slot are derived from self-reaction of the angular spectrum of plane waves and the discontinuity in the modal voltage. The numerical results are compared with those of the rigorous full-wave method and are shown to produce reasonably accurate data. And the stepped impedance microstrip low pass filter is designed and fabricated with the uniform and nonuniform DGS slots for improving the frequency responses. The experiments show that the proposed filter with slots in the ground plane has a wider stopband and sharper cutoff response.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.12
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• pp.1084-1096
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• 2016

This paper presents method of design and analysis of a high-speed serial interface connector with a data rate of 12.5 Gbps. A high-speed serial interface connector is composed of various material and complex structures. It is very difficult to match the impedance of each discontinuous portion of connector. Therefore, this paper proposes the structure of a connector line that be simplified a connector. In the structure of proposed connector line, this research presents a method for extracting R, L, C and G parameters, analyzing the differential mode impedance, and minimizing the impedance discontinuity using time domain transmissometry and time domain reflectometry. This paper applies the proposed methods in the connector line to the high-speed serial interface connector. The proposed high-speed serial interface connector, which consists of forty-four pins, is analyzed signal transmission characteristics by changing the width and spacing of the four pins. According to the analysis result, as the width of the ground pin increases, the impedance decreases slightly. And as the distance between the ground pin and the signal pin increases, the impedance increases. In addition, as the width of the signal pin increases, the impedance decreases. And as the distance between the signal pin and the signal pin increases, the impedance decreases. The impedance characteristic of initial connector presents ranges from 96 to $139{\Omega}$. Impedance characteristic after applying the structure of proposed connector is shown as a value between 92.6 to $107.5{\Omega}$. This value satisfies the design objective $100{\Omega}{\pm}10%$.