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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 14, Issue 12 - Dec 2003
Volume 14, Issue 11 - Nov 2003
Volume 14, Issue 10 - Oct 2003
Volume 14, Issue 9 - Sep 2003
Volume 14, Issue 8 - Aug 2003
Volume 14, Issue 7 - Jul 2003
Volume 14, Issue 6 - Jun 2003
Volume 14, Issue 5 - May 2003
Volume 14, Issue 4 - Apr 2003
Volume 14, Issue 3 - Mar 2003
Volume 14, Issue 2 - Feb 2003
Volume 14, Issue 1 - Jan 2003
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Performance Improvement of DS-CDMA Signal through MZ Modulator in Optical SCM Signal Transmission with Rake Receiver
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1113~1120
It is expected in the future that the demand of optical subcarrier multiplexing system, in which a number of small size base stations with only antenna and RF transmission are connected to central station using optical fiber, will be increased in the CDMA digital cellular mobile communication network. In this paper, in order to analysis the performance of optical SCM system fur CDMA RF signal transmission, MZ modulator is modelled as a non-linear transfer function with cubic operation. The performance degradation due to multipath signals and other user signals through MB modulator is analyzed and the performance is improved using the Rake receiver.
Design of Impulse Generator using Transistor
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1121~1126
In this paper we show impulse generator which is important component in UWB communication. There is two steps to generate monocycle impulse. In first step, Gaussian pulse was made by operation of transistor switching and operation time of transistor switching. The second step the high pass filter change from Gaussian to Monocycle impulse. The result of this impulse generator is impulse whose pulse width is 0,9 ns in time domain and amplitude is +/-250 ㎷.
Folded Multi-Strip Monopole Antenna
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1127~1133
In this paper, we proposed a novel folded multi-strip monopole antenna whose height is reduced using folded strip structure. It has a broadband characteristic and its measured impedance bandwidth ratio is approximately 1.85 : 1, from 4.55 GHz to 8.4 GHz, for VSWR
2. Proposed antenna has vertically polarized omni-directional conical beam radiation pattern. It maintains about the same radiation pattern over entire bandwidth.
A Hardware Implementation and Performance Analysis of STS Diversity System for CDMA2000 1x Environment
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1134~1142
This paper presents a hardware implementation of the STS diversity system, utilizing FPGAs and introduces the function and the design method of each of the modules of the system. In order to improve the performance of the implemented STS system which is an open loop transmit diversity system under fading environment, the exact estimation of the communication channel is essential. Therefore, we propose the optimal forgetting factor to estimate pilot channel in this paper, It is shown in this paper that the pilot channel is estimated using the forgetting factor of 0.7 without increasing the integration range of the pilot channel even when the power of pilot channel is not sufficiently large in CDMA 2000 1x signal environment.
Propagation Characteristics of Picosecond Gaussian Pulses in Coplanar Waveguides using Time Domain Measurement
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1143~1148
The distortion of picosecond pulses caused by dispersion as it propagates along microstripline and CPW(Coplanar waveguide) is investigated and measured using time domain measurement. Especially, this study presents that the distortion of these lines is analyzed and compared considering the relation between the dispersion effect and cut-off frequency(f
TE/) of fundamental TE mode for the substrate of line. To verify theoretical results, several samples of 50
lines are fabricated on the two kind of substrates with the different values of f
TE/. The propagation characteristics of picosecond Gaussian pulse on thess lines are simply measured using VNA(Vector Network Analyzer) with the time-domain analysis function.
Performance Comparison of the OFDM/SFH and OFDM/DS Systems in the Jamming Channel
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1149~1155
OFDM/SFH(orthogonal frequency division multiplexing/slow frequency hopping) system is the combination of OFDM communication system with frequency hopping(FH) method and OFDM/DS(orthogonal frequency division multiplexing/direct sequence) system combines the OFDM communication system with direct sequence(DS) method in terms of PN(pseudo noise) sequence. These two systems are also can be used for anti-jamming. In this study we analyze performances of OFDM/SFH system and OFDM/DS system with the equal information rate in partial band jamming and tone jamming channel. We find BER(bit error rate) in the variation of JFR(jamming fractional ratio) and JSR(jamming to signal power ratio) of the partial band jamming. Also, BER is found in the several JSR of the single tone or multi tone jamming. OFDM/DS system shows better performance than OFDM/SFH system in partial band jamming environment. OFDM/DS system has about 2.5 ㏈ SNR(signal to noise power ratio) gains than OFDM/SFH system when JFR=4/16 and JSR=0 ㏈ to meet BER=10
-3/. However, OFDM/SFH system has about 3 ㏈ SNR gains than OFDM/DS system at single tone jamming of JSR=5 ㏈. In multi tone jamming, performance of OFDM/SFH system is considerably degraded than OFDM/DS system.
ISAR Motion Compensation using Evolutionary Programming-Based Time-Frequency Analysis
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1156~1160
Many time-frequency analysis techniques have been used for motion compensated ISAR(Inverse Synthetic Aperture Radar) imaging. In this work, a novel time-frequency(T-F) analysis called evolutionary adaptive wavelet transform (EAWT) and evolutionary adaptive joint time-frequency(EAJTF) procedure are used for the motion compensated ISAR image. To show the validity of our algorism, we use simulated MIG-25 and Boeing 727(B-727) ISAR data. From the constructed ISAR image using EAWT and EAJTF, we show that our algorithm can obtain a clear motion compensated ISAR image such as other time-frequency analysis techniques.
Analysis of Axially Displaced Ellipse Gregorian Dual Reflector Antennas
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1161~1169
In this paper, ADE(Axially Displaced Ellipse) Gregorian dual reflector antennas, which are the special form of Gregorian dual reflector antennas, were analyzed. In the procedure of antenna analysis, the aperture field distribution was obtained by using the geometrical optics and their far-field radiation characteristics were analyzed by using the aperture field method. The analysis results such as antenna efficiency, HPBW(Half Power Beam Width), FNBW(First Null Beam Width), and FSL(First Sidelobe Level) were presented as functions of edge taper and size of main reflector and subreflector. From the results in this paper, we could confirm that ADE reflector antennas have the different radiation characteristics from the classical dual reflector antennas.
Investigation on the Output Power Improvement of Push-Push FET DRO with an Additional DR
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1170~1175
In this paper, the output power improvement of Push-Push FET DRO by adding the identical DR at the drain port as one used in the gate port, has been theoretically investigated. The investigation shows that the DR located between two microstrip lines locks the phase difference of two FET's outputs at 180 degree and improves the output power of Push-Push FET DRO. Since this effect can be used for correcting the impedance difference between two FETs output circuits and the electrical length error of the power combiner at the output circuit of Push-Push DRO, which may occur when fabricate the oscillator, the oscillator with an additional DR can be useful structure for fabricating oscillator.
Design and Implementation of Miniature VCO using LTCC Technique
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1176~1183
In this paper, miniature voltage-controlled oscillator(VCO) for 1.6 ㎓ PCS band is designed and implemented using the LTCC technique. Circuit level design using commercial components is performed, and passive L, C elements embedded in LTCC substrate is optimized by simulation tools. Embedded passive components are modeled into equivalent circuits and their circuit parameters are extracted for circuit simulation. Utilizing the designed embedded passive elements and 21 layers LTCC substrate, VCO with 4.0
1.6 ㎣ dimensions is designed and fabricated. Developed VCO operates in 2.7 V with 8.5 ㎃ current consumption. The phase noise performance of VCO is below -112.61 ㏈c/㎐ at 100 ㎑ offset and harmonic suppression characteristics is measured above -30 ㏈.
The Compensation Characteristics of WDM Channel Distortion Dependence on NRZ format and RZ Format
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1184~1190
In this paper, we investigated the characteristics of compensation for distorted NRZ signal and RZ signal in 320 Gbps WDM system as a function of channel input power, fiber dispersion coefficient and transmission length, respectively. The considered WDM transmission system is based on mid-span spectral inversion(MSSI) compensation method having highly nonlinear dispersion shifted fiber(HNL-DSF) optical phase conjugator(OPC) in the mid-way of total transmission line. We confirmed that the signal input power range compensated by MSSI is broadened by using RZ as a signal format in WDM system with small fiber dispersion coefficient, The range of fiber dispersion coefficient compensating overall distorted WDM channels is limited, because degree of compensation for distorted channel with low conjugated-wave power becomes gradually degrade as fiber dispersion coefficient becomes gradually higher. It is showed that RZ format and NRZ format is suited for long-haul transmission in WDM system with small fiber dispersion coefficient and with large fiber dispersion coefficient, respectively.
Performance Analysis of OFDM Communication System Cancelling the ICI by Data Conversion Method
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1191~1197
In the multi-carrier OFDM communication system, the inter-carrier-interference(ICI) produced by phase noise in the transceiver local oscillator makes a severe influence on the system performance. In this paper, a new ICI self-cancellation scheme in the data-conversion type is proposed to reduce effectively the ICI. Also, the common phase error(CPE), ICI and carrier to interference power ratio(CIR) are found by the linear approximation of the phase noise. Then, the proposed method is compared with the conventional OFDM to analyze the efficiency of system performance improvement. When the number of subcarriers is 64, there are respectively the SNR gain of 0.6 ㏈ in the phase noise variance of 0.3 with QPSK and 1.5 ㏈ in the phase noise variance of 0.1 with 16 QAM at BER=10
-3/. As a result, the performance degradation by ICI can be effectively lowered in the proposed system with ICI self. cancellation scheme, compared with the conventional OFDM system.
Design of Q-band Mode Converter with the Discontinuity Compensation and Its Application to Waveguide Mixer Module
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1198~1206
In this paper, a MMIC waveguide mixer module based upon the novel suggested mode converter for wave-guide-to-microstrip transition was fabricated and measured. The insertion and return losses of the mode converter was optimized by compensating the discontinuity effect between ridge and microstrip with the modification of 50
microstrip line pattern. Due to the low loss nature of the mode converter, a millimeter wave MMIC mixer chip can be successfully applied as a waveguide module for mmW waveguide communication system. The measured results of the module showed the successful MMIC chip application in waveguide and the negligible degradation of the supplied chip specification.
Radiation Characteristics of Log-Periodic Bent Dipole Antennas
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1207~1215
In this paper Log-Periodic Bent Dipole Antenna(LPBDA), which is composed of bent dipole elements instead of dipole elements, is proposed to reduce the size of Log-Periodic Dipole Antenna(LPDA). LPBDA for the operating frequency band of 1 ㎓∼3 ㎓ is designed and its radiation characteristics are analyzed by the moment method, and compared with radiation characteristics of LPDA. It is shown that although LPBDA decreases in size by about 20 %, radiation characteristics of LPBDA are similar to radiation characteristics of LPDA. Calculated results show good agreement with measured results.
Design of Dual Band Log-Periodic Dipole Antennas for the Cellular/IMT-2000 Band
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1216~1224
In this paper Dual Band Log-Periodic Dipole Antenna(DLPDA), which can be used at the Cellular/IMT-2000 band, is proposed. The proposed antenna is composed of 2 of Log-Periodic Dipole Antenna(LPDA) and parasitic elements. To investigate the reliability of the proposed antenna, DLPDA is designed at the cellular/IMT-2000 band and analyzed by using the method of moment, Numerical results are compared with measured results. It is shown that although the antenna length is 70 cm, its radiation characteristics satisfied the design goals of gain, VSWR and beamwidth at the Cellular/IMT-2000 band. From these results, the proposed DLPDA is confirmed as the dual band antenna which can be used at the cellular/IMT-2000 band.
Stable Analysis of Electromagnetic Scattering from Arbitrarily Shaped Conductors Coated with a Dielectric Material
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 14, issue 11, 2003, Pages 1225~1231
In this paper, we present the analysis of electromagnetic scattering from arbitrarily shaped three-dimensional conducting objects coated with dielectric materials. The integral equation treated here is the combined field integral equation(CFIE). The objectives of this paper is to illustrate that only the CFIE formulation is a valid methodology in removing the interior resonance problem, which occurs at a frequency corresponding to an internal resonance of the structure. Numerical results of radar cross section for coated conducting structures are presented and compared with other available solutions.