• Title/Summary/Keyword: Electromagnetic Pulse Measurement

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Design of X-band 40 W Pulse-Driven GaN HEMT Power Amplifier Using Load-Pull Measurement with Pre-matched Fixture (사전-정합 로드-풀 측정을 통한 X-대역 40 W급 펄스 구동 GaN HEMT 전력증폭기 설계)

  • Jeong, Hae-Chang;Oh, Hyun-Seok;Yeom, Kyung-Whan;Jin, Hyeong-Seok;Park, Jong-Sul;Jang, Ho-Ki;Kim, Bo-Kyun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.22 no.11
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    • pp.1034-1046
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    • 2011
  • In this paper, a design and fabrication of 40 W power amplifier for the X-band using load-pull measurement of GaN HEMT chip are presented. The adopted active device for power amplifier is GaN HEMT chip of TriQuint company, which is recently released. Pre-matched fixtures are designed in test jig, because the impedance range of load-pull tuner is limited at measuring frequency. Essentially required 2-port S-parameters of the fixtures for extraction optimal input and output impedances is obtained by the presented newly method. The method is verified in comparison of the extracted optimal impedances with data sheet. The impedance matching circuit for power amplifier is designed based on EM co-simulation using the optimal impedances. The fabricated power amplifier with 15${\times}$17.8 $mm^2$ shows the efficiency above 35 %, the power gain of 8.7~8.3 dB and the output power of 46.7~46.3 dBm at 9~9.5 GHz with pulsed-driving width of 10 usec and duty of 10 %.

Performance Evaluation of SHF Sensor for Partial Discharge Signal Detection on DC Rectifier (DC 정류기 부분방전 신호검출을 위한 SHF 센서의 성능평가)

  • Jung, Ho-Sung;Park, Young;Na, Hee-Seung;Jang, Soon-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.7
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    • pp.1056-1060
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    • 2012
  • Online monitoring system is becoming an essential element of railway traction system for utilized to condition based malignance management and various techniques currently employed in railway traction system. Among the various techniques, it is efficient to detect partial discharge signals by electromagnetic wave detection in order to detect insulation fault of rectifier. Although VHF (Very High Frequency), UHF (Ultra High Frequency) sensors were adopted to detect partial discharge of power facilities, due to characteristics of urban railway, excessive noise occurs from 500 MHz to 1.5 GHz on UHF bandwidth. In this paper a new measurement system able to monitoring the conditions of power facilities on DC substation in metro was studied and set up. The system uses UHF sensors to measure the partial discharge of the rectifier due to electric faulting and dielectric breakdown. Comparison and estimation for performance of SHF sensor which had devised to detect partial discharge signal of urban railway rectifier has conducted. In order to estimate performance of SHF sensor, we have compared the sensor with existing UHF sensor on sensitivity upon frequency bandwidth generated by pulse generator, and also we have verified performance of the SHF sensor by detection results of partial discharge signal from urban railway rectifier.

X-Band 50 W Pulse-Mode GaN HEMT Internally Matched Power Amplifier (X-대역 50 W급 펄스 모드 GaN HEMT 내부 정합 전력 증폭기)

  • Kang, Hyun-Seok;Bae, Kyung-Tae;Lee, Ik-Joon;Cha, Hyen-Won;Min, Byoung-Gue;Kang, Dong-Min;Kim, Dong-Wook
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.10
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    • pp.892-899
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    • 2016
  • In this paper, an X-band 50 W internally matched power amplifier is designed and fabricated using an $80{\times}150{\mu}m$ GaN HEMT that is developed by the $0.25{\mu}m$ GaN HEMT process of ETRI. The optimum source and load impedances are experimentally extracted from the loadpull measurement using impedance-transform-prematching circuits, and the transistor performance is predicted. The power performance of the internally matched power amplifier, whose matching circuits are fabricated on a substrate with ${\varepsilon}_r$ of 10.2, is measured under the pulsed mode of $100{\mu}s$ pulse period and 10 % duty cycle, and the best output power of 47.46 dBm(55.5 W) and the power-added efficiency of 46.6 % are obtained at 9.2 GHz. The output power of 47~47.46 dBm(50~55.7 W) is measured in 9.0~9.5 GHz, and the power-added efficiency is measured to be greater than 43 % in 9.0~9.3 GHz and above 36 % in 9.4~9.5 GHz.

Implementation about measurement of the head SAR and variable parameter according to operation control mode in brain MR study with 1.5Tesia (1.57 BRAIN MRI검사에서의 작동제어모드를 통한 두부 SAR측정과 변화인자에 관한 고찰)

  • Lee, Kyu-Su;Sim, Hyun;Moon, Ji-Hoon;Oh, Jae-Cheol
    • Proceedings of the KIEE Conference
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    • 2007.04a
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    • pp.58-60
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    • 2007
  • Magnetic Resonance Imaging(MRI) has become a very widely used medical procedur e. Clo.sed and open systems are typically used with static magnetic fields at or below 2 Tesla. BWhole body SAR(specific absorbsion rate) is the value of SAR averaged over the entire body of the patient over any period of 15 minutes. Head SAR is the value of SAR averaged over the head of the patient for any period of 10 minutes. SAR is a measure of the absorption of electromagnetic energy in the body' (typically in watts per kilogram (W/kg)). The normal operating mode comprises values of head SAR not higher than 3 W/kg. The second level controlled operating mode comprises values higher than 3 W/kg. Current FDA guidance limits the SAR in the whole body. including the head to a range of 1.5 to 4.0 W/kg, depending on the patient's clinical condition. SAR, limit restrictions are incorporated in all MRI systems. and domestic' s guidance limits the SAR in a part body. including the head to 3.2w/kg and less. The purpose of this study is to evaluate on change of head SAR in using MRI pulse sequence and to check if exceed 3.2(w/kg) level in domestic a part exposure through measured head SAR. 23 patient's the average head SAR of pulse sequence is that T2WI sagittal is 0.5375. T2WI axial(FSE) is 0.4817, T1WI axial(SE) is, 0.8179. FLAIR axial is 0.4580. GRE axial is 0.0077, Diffusion is 0.0824w/kg. The head SAR exposed per patient was proved 2.3845w/kg less than the international standard. Coefficient of correlation for the relations body weight and SAR or for the relations ETL(echo train length) and SAR is 1 value. Coefficient of correlation for the relations between TR(time to repeat) and SAR is -0.602 value. so SAR increased relative to weight body and ETL. But the relations between TR and SAR is negative definite.

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Development of an EMAT System for Detecting flaws in Pipeline (배관결함 검출을 위한 EMAT 시스템 개발)

  • Ahn, Bong-Young;Kim, Young-Joo;Kim, Young-Gil;Lee, Seung-Seok
    • Journal of the Korean Society for Nondestructive Testing
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    • v.24 no.1
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    • pp.15-21
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    • 2004
  • It is possible to detect flaws in pipelines without interruption using all EMAT transducer because it is a non-contact transducer which can transmit ultrasonic waves into specimens without couplant. And it ran easily generate guided waves desired in each specific problem by altering the design of coil and magnet. In the present work, EMAT systems have been fabricated to generate surface waves, and selectively the plate wave of $A_1\;or\;S_1$ mode. The surface wave of 1.5MHz showed a good signal-to-noise ratio without distortion in its propagation along a pipeline, while the $S_1$ mode of 800kHz and the $A_1$ mode of 940kHz were distorted according to their dispersive properties. The wider the excitation pulse becomes, the better the mode selectivity of the plate waves becomes. A pipe of 256mm inner diameter and 5.5m thickness with 5 flaws was used for comparing the flaw detectability among the modes under consideration.

Model Experiments and Behavior Analyses of The Tunnel Support Using TDR Sensor (TDR센서를 이용한 터널 지보재의 모형 실험과 거동해석)

  • Park, Min-Cheol;Han, Heui-Soo;Cho, Jae-Ho;Yang, Nam-Young
    • Journal of the Korean GEO-environmental Society
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    • v.12 no.9
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    • pp.35-45
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    • 2011
  • This paper is to analyze the behaviors of tunnel support by TDR(Time Domain Reflectometry) sensor using electrical pulse. To analysis the behaviors of tunnel support, Copper tape as sensing materials was studied for on-site installation. Copper tape to the top of the glass tape, foam tape, and shielding the lower part was used electromagnetic shield sheet. For a high sensitivity to load and fill out the measurement noise emissions has been developed for the production of materials. This sensing material through the tunnel model tests for the change by surcharge load in TDR data were analyzed. Varing stiffness and support of conditions were determined the change of TDR data through PVC pipe tunnel section model tests. By comparing TDR data and finite element analysis, the behaviors of the tunnel support materials were analyzed qualitatively.

A Preprocessing Method for Ground-Penetrating-Radar based Land-mine Detection System (지면 투과 레이더(GPR) 기반의 지뢰 탐지 시스템을 위한 표적 후보 검출 기법)

  • Kong, Hae Jung;Kim, Seong Dae;Kim, Minju;Han, Seung Hoon
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.4
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    • pp.171-181
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    • 2013
  • Recently, ground penetrating radar(GPR) has been widely used in detecting metallic and nonmetallic buried landmines and a number of related researches have been reported. A novel preprocessing method is proposed in this paper to flag potential locations of buried mine-like objects from GPR array measurements. GPR operates by measuring the reflection of an electromagnetic pulse from discontinuities in subsurface dielectric properties. As the GPR pulse propagates in the geologic medium, it suffers nonlinear attenuation as the result of absorption and dispersion, besides spherical divergence. In the proposed algorithm, a logarithmic transformed regression model which successfully represents the time-varying signal amplitude of the GPR data is estimated at first. Then, background signals may be densely distributed near the regression model and candidate signals of targets may be far away from the regression model in the time-amplitude space. Based on the observation, GPR signals are decomposed into candidate signals of targets and background signals using residuals computed from the estimated value by regression and the measurement of GPR. Candidate signals which may contain target signals and noise signals need to be refined. Finally, targets are detected through the refinement of candidate signals based on geometric signatures of mine-like objects. Our algorithm is evaluated using real GPR data obtained from indoor controlled environment and the experimental results demonstrate remarkable performance of our mine-like object detection method.

S-Band 300-W GaN HEMT Harmonic-Tuned Internally-Matched Power Amplifier (S-대역 300 W급 GaN HEMT 고조파 튜닝 내부 정합 전력증폭기)

  • Kang, Hyun-Seok;Lee, Ik-Joon;Bae, Kyung-Tae;Kim, Seil;Kim, Dong-Wook
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.29 no.4
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    • pp.290-298
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    • 2018
  • Herein, an S-band internally-matched power amplifier that shows a power capability of 300 W in a Long Term Evolution(LTE) band 7 is designed and fabricated using a CGHV40320D GaN HEMT from Wolfspeed. Based on the nonlinear model, the optimum source and load impedance are extracted from the source-pull and load-pull simulations at the fundamental and harmonic frequencies, and the harmonic impedance tuning circuits are implemented inside a ceramic package. The internally matched power amplifier, which is fabricated using a thin-film substrate with a high relative permittivity of 40 and an RF35TC PCB substrate, is measured at the pulsed condition with a pulse period of 1 ms and a duty cycle of 10%. The measured results show a maximum output power of 257~323 W, a drain efficiency of 64~71%, and a power gain of 11.5~14.0 dB at 2.62~2.69 GHz. The LTE-based measurement shows a drain efficiency of 42~49% and an ACLR of less than -30 dBc(excluding 2.62 GHz) at an average power of 79 W.

Performance analysis of SNR and BER for radiation pattern reconfigurable antenna (인체 부착용 방사패턴 재구성 안테나의 SNR 및 BER 성능 분석)

  • Lee, Chang Min;Jung, Chang Won
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.6
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    • pp.4125-4130
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    • 2015
  • This paper presents the communication performance for the radiation pattern reconfigurable antenna in the wearable device measuring bio signal (temperature, blood pressure, pulse etc.) of human body. The operational frequency is 2.4 - 2.5 GHz, which covers Bluetooth communication bandwidth. The maximum gain of the antennas is 1.96 dBi. The proposed antenna is efficiently transmitting and receiving signal by generating two opposite beam directions using two RF switches (PIN diode). Also, we investigated how radiation pattern changes according to three angles ($30^{\circ}$, $90^{\circ}$, $150^{\circ}$) of Top Loading. In this paper, we measured and compared the SNR (Signal-to-Noise Ratio) and BER (Bit Error Rate) performances of the proposed antennas in the condition between an ideal environment of anechoic chamber and smart house existing practical electromagnetic interferences (Universal Software Radio Peripheral, USRP). Throughout the comparing the results of the measurement of two cases, we found that the SNR is degraded over 5dB in average and BER is increased over ten times in maximum, therefore, it is confirmed that the error rate of receiving signal is increased. The measured results of SNR and BER value in this paper able to expect the performance degrading by the interference from the electromagnetic devices.