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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Korean Institute of Electromagnetic Engineering and Science
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Journal DOI :
The Korean Institute of Electromagnetic Engineering and Science
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Volume & Issues
Volume 21, Issue 12 - Dec 2010
Volume 21, Issue 11 - Nov 2010
Volume 21, Issue 10 - Oct 2010
Volume 21, Issue 9 - Sep 2010
Volume 21, Issue 8 - Aug 2010
Volume 21, Issue 7 - Jul 2010
Volume 21, Issue 6 - Jun 2010
Volume 21, Issue 5 - May 2010
Volume 21, Issue 4 - Apr 2010
Volume 21, Issue 3 - Mar 2010
Volume 21, Issue 2 - Feb 2010
Volume 21, Issue 1 - Jan 2010
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Pilot Assignment Method for the PAPR Reduction and Effective Channel Estimation in the SC-FDMA Communication System
An, Dong-Geon ; Ryu, Heung-Gyoon ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 21, issue 1, 2010, Pages 1~7
DOI : 10.5515/KJKIEES.2010.21.1.001
PAPR of the pilot symbols can be reduced down by the CAZAC sequence in the SC-FDMA communication system. However, it is very complicated and takes quite a long time to compute the interpolation between the OFDM information symbols for the channel estimation because the pilot data are trasmitted in the block type. Furthermore, situation will be much more serious in the severe fading channel. Actually the pilot insertion of the comb type is much efficient and convenient for the channel estimation since the calculation of the interpolation can be made in the frequency domain symbol by symbol. But, the PAPR will be regrown when the pilot data are inserted with the information data in the comb type. So, in this paper, we like to study the PAPR reduction and comb type pilot assignment for the efficient channel estimation. Unlike the conventional SLM(selected mapping) method requiring the side information, our improved SLM method is to use the phase rotation sequence into information data without rotating phase of pilot. We use different pilot data according to the different phase rotation sequence. From the simulation result, it can be confirmed that when SLM method of 4 phase rotation sequence is used, PAPR is almost same to the block type method without pilot.
Modified Hairpin Filters Improving the Suppression Performance of Stop-Band
Kim, Bong-Su ; Kang, Min-Soo ; Byun, Woo-Jin ; Kim, Kwang-Seon ; Song, Myung-Sun ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 21, issue 1, 2010, Pages 8~13
DOI : 10.5515/KJKIEES.2010.21.1.008
In this paper, a new hairpin type strip-line BPF(Band Pass Filter) improving the suppression performance of unwanted frequency signal is studied. A modified hairpin filter is designed by classical hairpin filter design methodology and is realized by newly placing structure of designed filter. And a newly formed coupled-line effects between modified bilateral symmetry structures make the transmission zeros. Each transmission zeros can shift its frequency to wanted frequency by tuning a certain part of filter. To investigate the validity of this novel technique, an order-5 Chebyshev BPF centered at 9.2 GHz with a 15 % FBW(fractional bandwidth) were used. According to design and measurement results, a good performance of insertion loss of 0.8 dB and unwanted signal suppression of maximum 50 dB is achieved at full input/output ports.
Improvement of Radar Images Using Time-Frequency Transform
Jung, Sang-Won ; Kim, Kyung-Tae ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 21, issue 1, 2010, Pages 14~19
DOI : 10.5515/KJKIEES.2010.21.1.014
In this paper, an efficient algorithm is developed to perform target rotational motion compensation to achieve the clear inverse synthetic aperture radar(ISAR) image. The algorithm is based on a time-frequency technique. This algorithm provides an efficient method to resolve the blurring image caused by the time-varying behavior of the target scattering centers and leads to a well-focused ISAR image. Results demonstrate that the time-frequency techniques can improve the blurring ISAR image when an aircraft is in complex motion, such as maneuvering, rotation and acceleration.
Study on Space-Time Adaptive Processing Based on Novel Clutter Covariance Matrix Estimation Using Median Value
Kang, Sung-Yong ; Jeong, Ji-Chai ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 21, issue 1, 2010, Pages 20~27
DOI : 10.5515/KJKIEES.2010.21.1.020
In this paper, we presented a signal model of STAP and actual environment of clutter. The novel estimation method of clutter covariance matrix using median value is proposed to overcome serious performance degradation after NHD in nonhomogeneous clutter. Eigen value characteristic is improved through diagonal loading. Target detection ability and SINR loss of the proposed method though MSMI statistic is also compared with conventional method using average value. The simulation results, confirm the proposed method has better performance than others.
A Design of the UWB Bandpass Filter with a Good Performance of the Stopband, and Notched Band in Passband
An, Jae-Min ; Kim, Yu-Seon ; Pyo, Hyun-Seong ; Lee, Hye-Sun ; Lim, Yeong-Seog ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 21, issue 1, 2010, Pages 28~35
DOI : 10.5515/KJKIEES.2010.21.1.028
In this paper, we designed and fabricated a ultra-wideband(UWB) bandpass filter with a good performance of a stopband, and a notched band in passband. The transformed equivalent circuit of the highpass filter was realized by distributed element. A wide-passband with 3-dB fractional bandwidth of more than 100 % was achieved by using optimum response of the HPF. For improving lower and upper stopband characteristic, a cross coupling between feed lines was employed, which was analyzed by desegmentation technique. In order to reject interference of Wireless LAN and Hyper LAN(5.15~5.825 GHz), the narrow notched(rejection) band was realized by a spurline. The fabricated BPF indicated the passband from 3.1 to 10.55 GHz and the flat group delay of less than 0.94 ns over the entire passband except the rejection band. The filter shown sharp attenuation both inside and outside the band and notched band from 5.2 to 6.12 GHz.
New Design Method of Wireless Power Transfer System Using Loop Antennas
Kim, Hee-Seung ; Won, Do-Hyun ; Lim, Jae-Bong ; Jang, Byung-Jun ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 21, issue 1, 2010, Pages 36~45
DOI : 10.5515/KJKIEES.2010.21.1.036
In this paper, we propose a new design method to design a wireless power transfer system using loop antennas for consumer electronics. This method can simply design a wireless power transfer system only using measurements of coupling coefficients and simple equations of equivalent circuit model about loop antennas without complicated electromagnetic analysis. Using the proposed design method, a wireless power transfer system with a pair of loop antennas operating at the frequency of 13.56 MHz, which have a dimension of
, is designed and implemented. The input return loss, coupling coefficient, efficiency, and input impedance variation with respect to a distance between loop antennas were measured. The proposed design method provides good agreements between measured and predicted results. Also, the wireless power transfer system with impedance matching circuits designed by the proposed design method shows two times higher efficiency characteristics than the case with the general
impedance matching circuits. Therefore, we verified that our design method could be an effective tool to design a wireless power transfer system.
A Reconfigurable Circularly Polarized Microstrip Antenna on a Cross-Shape Slotted Ground
Yoon, Won-Sang ; Han, Sang-Min ; Lee, Dong-Hyo ; Lee, Kyoung-Joo ; Pyo, Seong-Min ; Kim, Young-Sik ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 21, issue 1, 2010, Pages 46~52
DOI : 10.5515/KJKIEES.2010.21.1.046
A compact circular microstrip patch antenna with a switchable circular polarization(CP) is proposed at 2.4 GHz. An unequal cross-shaped slot on a ground plane is utilized as a perturbation. By switching pin diodes mounted on the slot, the CP sense of each antenna can be simply switched from left-handed(LH) CP to right-handed(RH) CP vice versa. Since the perturbation can be made on the ground plane and no bias circuit is required on the patch side, the bias circuit has not effect on the main beam radiation. From the experimental results, the impedance bandwidth and CP bandwidth of the proposed antenna have shown up to 150 MHz and 35 MHz, respectively. The peak gain of the proposed antenna is 1.7 dBi for both CP senses.
Design of Variable Gain Low Noise Amplifier with Memory Effects Feedback for 5.2 GHz Band
Lee, Won-Tae ; Jeong, Ji-Chai ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 21, issue 1, 2010, Pages 53~60
DOI : 10.5515/KJKIEES.2010.21.1.053
This paper presents a novel gain control system composed of a feedback circuit, Two stage Low Noise Amplifier (LNA) using 0.18 um CMOS technology for 5.2 GHz. The feedback circuit consists of the seven function blocks: peak detector, comparator, ADC, IVE(Initial Voltage Elimination) circuit, switch, storage, and current controller. We focus on detecting signal and designing storage circuit that store the previous state. The power consumption of the feedback circuit in the system can be reduced without sacrificing the gain by inserting the storage circuit. The adaptive front-end system with the feedback circuit exhibits 11.39~22.74 dB gain, and has excellent noise performance at high gain mode. Variable gain LNA consumes 5.68~6.75 mW from a 1.8 V supply voltage.
Size Reduction of a Quasi Class-E High Power Amplifier Using Defected Ground Structure
Choi, Heung-Jae ; Jeong, Yong-Chae ; Lim, Jong-Sik ; Jung, Young-Bae ; Eom, Soon-Young ; Kim, Chul-Dong ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 21, issue 1, 2010, Pages 61~68
DOI : 10.5515/KJKIEES.2010.21.1.061
In this work, a reduced size 20W quasi class-E Power Amplifier(PA) with defected ground structure load-network is presented for WCDMA base station application. Harmonic impedances required for the class E operation are satisfied by applying the dumbbell and the asymmetric spiral DGS. Open impedance for 2nd harmonic frequency which has the highest power and nearly short impedances for other higher order harmonics are provided by the proposed DGS load-network. The maximum Power Added Efficiency(PAE) of 70.2 % at the output power of 43.1 dBm with the saturated power gain of 12.7 dB is achieved by the proposed quasi class-E PA, which is comparable to the performance of the reference class-E PA. Total size of the proposed class-E PA is only
and much smaller than the conventional class-E PA that is loaded with a number of open stubs.
Design of a Wideband Frequency Synthesizer with Low Varactor Control Voltage
Won, Duck-Ho ; Choi, Kwang-Seok ; Yun, Sang-Won ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 21, issue 1, 2010, Pages 69~75
DOI : 10.5515/KJKIEES.2010.21.1.069
In this paper, with using the clapp type VCO(Voltage Controlled Osillator) configuration a wideband frequency synthesizer in UHF band is proposed. In order to design a wideband frequency synthesizer, the variation of phase in the negative resistance circuit as well as the load circuit was analyzed. Based on this result we propose a method to widen the operation range of the VCO. A frequency synthesizer using the proposed wideband VCO was designed and fabricated. It is shown that the synthesizer has the operating frequency range of 740~1,530 MHz by 0~5 V varactor tuning voltage, and it had the output power of 2~-6 dBm. Moreover, the phase noise measured as -77 dBc/Hz at 10 kHz offset, and as -108 dBc/Hz at 100 kHz offset from the oscillation frequency.
Performance Analysis of Block Linear MMSE Equalization for OFDM Systems in Doubly Selective Channels
Lim, Dong-Min ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 21, issue 1, 2010, Pages 76~82
DOI : 10.5515/KJKIEES.2010.21.1.076
In this paper, we analyze the performance of the block linear MMSE equalization for OFDM systems in doubly selective channels by computer simulations. The block linear MMSE equalization shows somewhat unusual BER characteristics in that the BER curve drops at first as SNR increases but then rises up as SNR increases further beyond some point. In this paper, we investigate the BER characteristics of the block linear MMSE equalization by analyzing the condition number of the coefficient matrix in the linear system involved in the equalization process, and propose a new method to avoid the BER performance degradation at high SNR.
A Ku-Band Hair-Pin Resonator Oscillator with a New Varactor Coupled Line Structure
Choi, Kwang-Seok ; Won, Duck-Ho ; Yun, Sang-Won ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 21, issue 1, 2010, Pages 83~89
DOI : 10.5515/KJKIEES.2010.21.1.083
In this paper, we propose a new varactor coupled line structure and design the VCO using the proposed structure. The proposed coupled line structure removes the reflected signals from the varactor diode using an added
/4 transmission line. The frequency synthesizers are designed using the PLL technique at Ku-band. The synthesizer using the proposed coupled structure has 38 MHz frequency tuning range and -97 dBc/Hz phase noise characteristic at 100 KHz offset frequency. The measured results show improved tuning range as well as the improved phase noise characteristics compared to the conventional designs.
Improvement of Radiation Performance of Mobile Phone Antenna Using PIFA on U-Shaped Ground Plane
Lee, Jeong-Ho ; Song, Jae-Kwan ; Yook, Jong-Gwan ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 21, issue 1, 2010, Pages 90~97
DOI : 10.5515/KJKIEES.2010.21.1.090
In this paper, we propose antenna topology and ground plane shape to improve the performance of PIFA (Planar Inverted F Antenna) which is built-in mobile phone. First, we designed the PIFA antenna consists of multiple radiators to provide multi-current paths. Then we designed U-shaped ground plane on the PCB under the antenna. The proposed antenna structure shows TRP/TIS improvement of 2.0 dB/3.7 dB for GSM and 2.2 dB/ 2.0 dB for DCS and 0.8 dB/1.5 dB for PCS and 1.3 dB/0.7 dB for WCDMA at the free space.