• Journal of electromagnetic engineering and science
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• v.11 no.2
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• pp.91-96
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• 2011

In this paper, we propose a microstrip bandpass filter using stepped-impedance coupled-line hairpin resonators. The stepped-impedance coupled-line hairpin resonator has extended harmonic suppression in comparison with a conventional hairpin resonator due to transmission zero and the movement of harmonic frequencies resulting from the stepped-impedance characteristic. A high-pass type impedance/admittance inverter is employed in order to improve the lower frequency skirt characteristics of the passband. A 4-pole bandpass filter is designed and fabricated at 1.8 GHz. The measured results show the excellent attenuation performance at the stopband which is greater than 30 dB up to 10 GHz.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2345-2347
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• 2005

In this paper, impedance characteristics of overhead medium-voltage (MV) power lines is reported for power line communication (PLC) over an MV power line network. For analysis, a two-port equivalent network model of MV power lines is derived. By applying the transmission line theory, reflection behavior and impedance of power lines are investigated. For verification, impedance of power lines is measured at a test field for an MV PLC. The results show that impedance of MV power lines is between $200{\Omega}$ and $300{\Omega}$ and converges to a half of their characteristic impedance.

• Journal of electromagnetic engineering and science
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• v.9 no.2
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• pp.85-97
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• 2009

As operating frequency is raised and as more integration with active and passive elements is required, it becomes difficult to fabricate more than 120 ${\Omega}$ characteristic impedance of a mierostrip line. To solve this problem, an equivalent high impedance transmission-line section is suggested, which consists mainly of a pair of coupled-line sections with two shorts. However, it becomes a transmission-line section only when its electrical length is fixed and its coupling power is more than half. To have transmission-line characteristics(perfect matching), independently of coupling power and electrical length, two identical open stubs are added and conventional design equations of evenand odd-mode impedances are modified, based on the fact that the modified design equations have the linear combinations of conventional ones. The high impedance transmission-line section is a passive component and therefore should be perfectly matched, at least at a design center frequency. For this, two different solutions are derived for the added open stub and two types of high impedance transmission-line sections with 160 ${\Omega}$ characteristic impedance are simulated as the electrical lengths of the coupled-line sections are varied. The simulation results show that the determination of the available bandwidth location depends on which solution is chosen. As an application, branch-line hybrids with very weak coupling power are investigated, depending on where an isolated port is located, and two types of branch-line hybrids are derived for each case. To verify the derived branch-line hybrids, a microstrip branch-line hybrid with -15 dB coupling power, composed of two 90$^{\circ}$ and two 270$^{\circ}$ transmission-line sections, is fabricated on a substrate of ${\varepsilon}_r$= 3.4 and h=0.76 mm and measured. In this case, 276.7 ${\Omega}$ characteristic impedance is fabricated using the suggested high impedance transmission-line sections. The measured coupling power is -14.5 dB, isolation and matching is almost perfect at a design center frequency of 2 GHz, showing good agreement with the prediction.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.377-383
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• 2003

As the high-speed data communications such as xDSL using the existing copper cable come into wide use, the electromagnetic coupling characteristics of telecommunication cables become more significant. In order to describe the screening performance of telecommunication cable, the transfer impedance of cable shield is required. This paper describes the transfer impedance for two types of telecommunication cables using the line injection method of IEC 96-1. Results are analyzed to show how the materials of cable shields, the positioning of the injection line and of the inner conductor of the CUT(Cable Under Test) affect the value of transfer impedance. We then propose the transfer impedance model of telecommunication cable based on the measurements.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.37-40
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• 2001

Subject of this paper is analysis of channel noise and impedance characteristics for high speed power line communication to concerned noise of transmission line and impedance in the frequency range up to 30MHz. Parameters of transmission line was inducted from experimentally power line channel measurement. Moreover, Analysis of compared based on measurement of channel characters with simulation test for appear characters.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.11
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• pp.67-78
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• 2005

In this paper, impedance characteristics of overhead medium-voltage (MV) power line for power line communication (PLC) is analyzed. For analysis, a two-port equivalent network model of MV power lines is derived. By applying the equivalent model and basic transmission line theory, input impedance at the signal induction part is calculated. And also calculated input impedance of power line itself that the medium voltage coupler and coaxial cable effect are removed. For verification, impedance of power lines is measured at a test field for an MV PLC. The results show that impedance of MV power line itself is between $200\;{\Omega}\;and\;300\;{\Omega}$ and converges to a half of their characteristic impedance with increasing frequency. And also measured data is very similar to calculated data.

• Journal of the Korean Society for Railway
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• v.9 no.2 s.33
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• pp.237-243
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• 2006

Deicing system is to melt frost or ice freezed in catenary line when the temperature is lower than $0^{\circ}C$ in winter. The principle of deicing system is to melt frost or ice by Joule heat of catenary impedance. The performance of deicing is dependant of deicing current determined by the length of deicing section, deicing impedance and current division ratio of catenary line and messenger line. So, we present technique for estimating deicing current and process for determination of deicing section in the conventional line. Deicing impedance is estimated using Carson-Pollaczek equation, and current division ratio of catenary line and messenger line is estimated using voltage drop, and deicing current is estimated using power system data of deicing system. For the determination of the final deicing section, we verified estimated value comparing with experiment value of deicing impedance and current division ratio of catenary line and messenger line using low voltage experiment. Finally, we verified the validity of estimation technique and process using a simulated test data of real deicing system operation in the Chungju Substation, Chungbuk line.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1585-1591
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• 2009

This paper describes a new method for extracting characteristic impedance of transmission line using Substrate Integrated Artificial Dielectric (SIAD). The new procedure to calculate the characteristic impedance of SIAD transmission line is described with the proper equations and basic transmission line theory. The characteristic impedance is determined as an almost fixed value in the proposed method, while it fluctuates according to frequency in the previous method. As the result, the effective dielectric constant of SIAD transmission line is calculated as a fixed value rather than fluctuating one. In order to show the validity of the proposed method, SIAD microstrip lines are simulated and measured, and characteristic impedances and effective dielectric constant are calculated and compared to the previous method.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.383-386
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• 2001

Distance relay is tripped by the line impedance calculated at the relay point. Accordingly the accurate operation depends on the precise calculation of line impedance. Impedance can be accurately calculated in case of overhead line. However, in case of power cables or combined transmission lines, impedance can not be accurately calculated because cable systems have the sheath, grounding wires, and cable cover protection units (CCPUs). There are also several grounding systems in cable systems. Therefore, if there is a fault in cable system, these terms will severely be caused much error to calculation of impedance. Accordingly the proper compensation should be developed for the correct operation of the distance relay. This paper presents the distance calculating algorithm in combined transmission line with power cable using wavelet transform. In order to achieve such purpose, judgement method to discriminate the fault section in both sections was proposed using db1 coefficient summation. And also, error compensation factor was proposed for correct calculation of impedance in power cable.

• Journal of the Korean Institute of Telematics and Electronics
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• v.7 no.4
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• pp.1-5
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• 1970

This presents the way in shich the input impedance, and the output waveform of the line discriminator are influenced by a discrepancy of less than $\pm$10% in the coupling resistor resistance from the optium value(Characteristic impedance of the transmission line used in the line discriminator)