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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 10, Issue 7 - Dec 1999
Volume 10, Issue 6 - Oct 1999
Volume 10, Issue 5 - Sep 1999
Volume 10, Issue 4 - Aug 1999
Volume 10, Issue 3 - Jun 1999
Volume 10, Issue 2 - Apr 1999
Volume 10, Issue 1 - Feb 1999
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Performance of DS-CDMA forward Link Due to Nonlinear Power Amplifier in Multiuser Environment
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 479~486
In this paper the system performance degradation resulting from nonlinear transmitter power amplifier which is essential to increase the efficiency is analyzed in a forward link CDMA system. The power amplifier is modeled by power series model which includes only odd-order terms. The effects of power amplifier's nonlinearity such as intersymbol interference, phase distortion on the RF system performance were visualized by examining the distorted time domain waveforms, signal vector constellation. And through the investigation of the power spectrum density of the transmitted signal, spectral regrowth or sideband regrowth which is result from amplitude distortion can be seen. All these characteristics result in BER performance degradation due to other user interferences and intersymbol interference. The analysis technique described here applies not only to power amplifier but also to any other nonlinear components such as mixers and switches. Also the effects of adjacent channel interference and supurious emission can be analysed between different systems.
Performance Analysis of MC-CDMA Systmes for Wireless ATM
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 487~497
In this paper, the performances of MC-CDMA systems for wireless ATM(WATM) is analyzed through computer simulations. The proposed MC-CDMA systems can support the 25 Mbps data rate with about 18.2 MHz bandwidth at 5 GHz carrier frequency, satisfying the specifications of wireless physical layer proposed by Wireless ATM Working Group(WATM WG). For the channel coding strategies, convolutional code, TCM and Turbo TCM(T-TCM) are explored and their performances are compared. From the simulation results, T-TCM becomes superior to the other coding schemes as interative decoding is performed.
Analysis of Characteristics for Strip Line with a Ferrite Material using Spectral-Domain Method
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 498~505
The ferrite device that has nonreciprocal characteristics has been used as various microwave components. In this paper, the spectral-domain method was used to analyze the characteristics of structure(strip line on multilayer structure with ferrite material) for which no paper has been published yet. It is assumed that an external dc magnetic field is applied perpendicular to the ground conductor. The propagation constant is calculated for each parameter and frequency. Also we considered convergence by increasing the number of basis functions and verified the numerical analysis results. From the results, we could confirm that as the thicknesses of YIG is increased, the cutoff region is widened and the propagation constant is decreased at the frequency of upper cutoff region. For a larger applied dc magnetic field, the frequency of cutoff region is found to be increased. Also the simulation results for strip line show that the cutoff region is widened and the propagation constant is larger than that of microstrip line.
Performance Improvement of DS-CDMA System by Multi-User Interference Cancellation Techniques
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 506~519
An adaptive array antennal and a CCI canceller have been considered as techniques for cancelling Multi-User Interference(MUI) in Direct Sequence Code Division Multiple Access(DS-CDMA) system. These techniques have different problems respectively in the process of cancelling MUI as the number of users increases. For that reason, the scheme which can cancel MUI effectively by compensating for the problems of each of the techniques has been required. For the scheme, the technique to connect an adaptive array antenna and a CoChannel Interference(CCI) canceller in cascade form has been studied. In the existing study about the cascade connection method, the effect of cancelling MUI about two interference signals is analyzed, but the analysis for the quantitative BER(Bit Error Rate) improvement according to the number of users is not considered. Therefore, in this paper, we have analyzed the degree of BER performance improvement quantitatively according to the number of users by introducing the receiving system, which connects an adaptive array antenna and a CCI canceller to a DS-CDMA system in cascade form. For the method of analyzing the performance, we have performed the theoretical analysis and the simulation, considering the case of adopting only an adaptive array antenna and of cascade connection respectively, and having compared and analyzed the results. From the results, it is confirmed that in the case of adopting only an adaptive array antenna, the problems occur in the process of cancelling MUI according to the number of users and the receiving direction of interference signals, and can be compensated by the cascade connection method. In conclusion, we have known that MUI is cancelled effectively by using the cascade connection method, and the much better BER performance improvement is obtained.
Investigation of Validity of Exposure Limits for Electromagnetic Field in RF Band
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 520~529
Exposure limits for human protection are determined by converting basic limits for induced current, SAR(specific absorption rate), or power density, which are based upon biological effects, to measurable electric and magnetic field intensities. As a part of studies for the establishment of a domestic guideline for exposure limits, the validity of the exposure limits of five representative guidelines or standards, which are derived from basic limits, are investigated in this paper, using the published results for coupling mechanisms of electromagnetic field into a human body, and problems in each standard are analyzed and compared with each other.
Design and Fabrication of Rectangular Iris Waveguide Filter for Microwave Broadcasting Transponder
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 530~538
In this paper, design of rectangular iris waveguide filter for the microwave broadcasting transponder using WR137 is applied to the modified
mode theory in order to exactly analyze the characteristic of the waveguide discontinuity. We designed and fabricated the rectangular iris waveguide filter with the bandwidth 47 MHz for the microwave broadcasting transponder applied the conjugate gradient method to the modified
mode theory. The results show a good characteristics that the
are -23 ㏈, -0.56 ㏈ and the maximum VSWR is below 1.02 in the passband.
Performance of Radio Communication DS/CDMA System with Diversity Technique and BCH Coding under Impulsive Noise and Nakagami Fading
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 539~549
In this paper, the bit error rare (BER) performance of DS/CDMA DQPSK communication system in the presence of multi access interference, impulsive noise and Nakagami fading is investigated. The DS/CDMA DQPSK communication system adopts Maximum Ratio Combining (MRC) diversity reception and error correcting BCH code technique to enhance system performance. Using the derived error probability equation, the error rate performance of DS/CDMA DQPSK communication system has been evaluated and shown in figures to discuss as a function of impulsive index(A), Gaussian noise to impulsive noise power ratio(
'), multi access interference(Κ), Nakagami fading parameter(m), the number of diversity branch (Ｌ), the number of error correction symbol (t), PN code sequence length(N) and
. The error performance of DS/CDMA-MDPSK signals improve by adopting MRC diversity and BCH(15,7) coding technique in the environment of impulsive noise plus Nagakami fading. From the results, we known that proposed system is affected by multi access interference, impulsive noise and Nakagami fading in radio communication system environment. Also, BER performance of DS/CDMA DQPSK communication system cam be improved increasing either the power of desired signal or the value of Gaussian noise to impulsive noise power ratio. And BCH(15,7) code technique is more effective to restrain the affection of multi access, interference, impulsive noise and Nakagami fading in DS/CDMA DQPSK communication system than MRC diversity reception technique.
Wavelet-Galerkin Scheme of Inhomogeneous Electromagnetic Problems in the time Domain
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 550~563
A wavelet-Galerkin scheme based on the time-dependent Maxwell's equations is presented. Daubechies wavelet with two vanishing wavelet moments is expanded for basis function in spatial domain and Yee's leap-frog approach is applied. The shifted interpolation property of Daubechies wavelet family leads to the simplified formulations for inhomogeneous media without the additional matrices for the integral or material operator. The stability condition is formulated. The dispersion characteristics are analyzed and compared with those of finite difference time domain and multiresolution time domain methods. The analyses show the excellent trade-off between the regularity and the support width of the basis function. Although the basis function has only two vanishing wavelet moments, it is enough to provide negligible dispersive error in the numerical analysis and its compact support enables only several involved terms per nodes. The storage effectiveness, execution time reduction and accuracy of this scheme are demonstrated by calculating the resonant frequencies of the homogeneous and inhomogeneous cavities.
Development of a New Vehicle Detector Combining CW Radar and Magnetometer Techniques
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 564~581
This paper introduces a new, small, low cost, robust and quick replaceable pavement-based vehicle detector using CW radar, magnetometer, and UHF small antennal techniques. The detector has been developed for a replacement of loop detectors having wide surface areas, for a more accurate operation under all weather conditions, and for no algorithmic change of the existing traffic information system. The detected vehicle information is sent by a small helical antenna embedded in a plastic material and received by a 5/8
long GP antenna for signal processing. In a relatively good weather condition, the detector operates at 24 GHz. But in a heavy rain condition, magnetometer is activated by automatic switching.
A Study on the Design and Fabrication of Diplexer Using H-plane T-junction for KOREASAT-III Transponder
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 582~593
This paper presents the design and fabrication of the diplexer for a KOREASAT-III Ka-band satellite transponder. The transmission characteristics of the diplexer is analyzed by calculating the generalized scattering matrix using mode matching method. It is composed of 2 bandpass filters, coupled with H-plane T-junction having symmetrical inductive iris and E-plane metal insert structures. Compared with the size and weight of the Rx and Tx filter loaded with a transponders respectively, those of the diplexer can be effectively reduced. In a high power transmission, the variation of the filter characteristics is minimized by the scheme that irises are extended to the exterior of H-plane of the waveguide. This scheme needs no extra heat sinks for dissipating high power. The diplexer is designed to improve the simplification, durability and reliability by eliminating tuning screws, which have been used to compensate for the characteristics of fabricated filters. The bandpass filters of the diplexer show the insertion loss of less than 1.2 dB and the return loss in excess of 15 dB. The isolations of more than 65 dB have been achieved between Rx and Tx filter.
Electromagnetic Scattering Resonances on a Periodic Strip Grating on a Grounded Dielectric Slab: Bragg Blazing Phenomena of TE Polarization Case
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 594~606
The electromagnetic scattering characteristics by a periodic strip grating on a grounded dielectric slab for TE polarization case is examined from the viewpoints of both the reflection grating and the leaky wave antenna problems. Numerical results for two kinds of Bragg blazing (resonance type and non-resonance type) phenomena are given and some discussions on the properties such as complex propagation constants, scattering characteristics, and distributions of strip current density are presented.
A Study on the Diversity Scheme with Directional Antennas for Indoor Environments
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 607~617
In this paper, we fabricated dual polarization microstrip array antenna to analyze the performance of polarization diversity of each antennas beamwidth and recommend suitable polarizations diversity antenna under indoor environments. The proposed antennas which have directional beam patterns are small, light and thin. Also they are
array antenna with
beamwidth, respectively. The center frequency is 1890 MHz, IMT-2000's frequency. We also measured the antennas characteristics of each beamwidth in various waveguide structured corridor and compared then with the case of space diversity using the dipole antenna. The measurement shows that the polarization diversity using directional dual polarization microstrip array antennas has more 1~7 dB diversity gain than the space diversity using the dipole antenna. Therefore, the proposed antennas are expected to be efficiently used for the design of optimal directional beam pattern antenna and diversity system for indoor environments.
Design of Stacked Microstrip Antennal for DBS Reception
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 618~627
In this paper, we have researched designing a microstrip antenna, which will be replaced for a parabolic antenna. A microstrip antenna has been used in extremely limited field, but if it is applied to practical life like a DBS receiving antenna, we expect that it will be used in various way. First of all, if we use a microstrip antenna for a DBS receiving antenna, it should be guaranteed characteristics of broadband frequency. Therefore, the goal of this paper is designing an antenna which guarantees broadband frequency band for a DBS reception. Also, experiment with Koreasat, we have researched the propriety of this antenna for the DBS receiving antenna.
Wideband Circularly Polarized Microstrip Array Antennal Adopting Sequential Rotation Method Using Shortened Phase Delay
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 628~635
At center frequency of 11.85 GHz, wideband left-handed circularly polarized microstrip array antenna is designed with the method of sequential ratation based on
phase delay). Its return loss, axial ratio bandwidth, radration pattern, and gain are compared with those adopting sequential rotation based on
phase delay). The
array is manufactured and measured. The results show that 10 dB return loss bandwidth is 10.51~12.74GHz(18.82%) which is 1.57 times wider than the case using
sequential rotation method, 3 dB axial ratio bandwidth is 11.43~12.5 GHz(9.03%) which is 1.25 times as wide as that using
sequential rotation method and the antennal gain is 25.4 dB. The results of mesurements are almost similar to those of simulation.
Aperture-Coupled Wideband U-slot Microstrip Patch Antenna at Ku Band
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 4, 1999, Pages 636~644
Experimental and simulation results are presented on the Aperture-Coupled microstrip patch antennal with U-shaped slot. Experiment and simulation results include impedance bandwidth, copolar and crosspolar-pattern characteristics and gain measurements. Simulation results show the advantages of U-slotted patch antenna comparing with the normal patch antenna. More than 35% impedance bandwidth is obtained with reasonably restricted cross-polar radiation pattern. The U-slotted radiation element fed by aperture-coupling method can be more easily extended to array structure, compared with that fed by coaxial cable.