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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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The Bandwidth Efficiency Increasing Method and Performance Evaluation of Binary Input MC-CDMA
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 319~328
It is necessary to devise the method for increasing bandwidth efficiency in order to provide the high speed mobile multi-media communication services with CDMA under the limited radio bandwidth resources. In this paper the structure for transmitting the high speed data at the half bandwidth of the required bandwidth using the symmetry property of the IFFT output of the binary input MC-CDMA, which enables the time scaling method utilized, is proposed. The processing gain is increased 4 times than the DS-CDMA and its performance is evaluated as better than DS-CDMA with rake receivers under the Rayleigh fading channel and same bandwidth per one channel.
Analysis and Characteristics of Log-Periodic X Dipole Antennas
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 329~339
LPXDA(Log-Periodic X Dipole Antenna), consisting of X dipole elements, was proposed as a Log-periodic antenna with short boom length and good Performance relative to LPDA(Log-Periodic Dipole Antenna) . LPXDA for operating frequency band of 500 MHz~l,000 MHz was designed and radiation characteristics of the designed antenna was analyzed by moment method, and compared with LPDA characteristics. The proposed LPXDA, in this paper, was found to have shorter boom length by 20% and better radiation characteristics with variations of frequency relative to the LPDA. The calculated results show good agreement with measurements.
Analysis of W-type Reflector Antennas Using the Method of Moments
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 340~350
In this paper, W-type reflector antennas modified from corner reflector antenna structure were proposed and the radiation characteristics were analyzed using the method of moments. The analysis results such as gain, F/B, half power beamwidth, and radiation pattern are presented as functions of dipole height h and back edge spacing d. Also, the proposed antenna was compared with corner reflector antennas in the same size of side reflectors, W-type reflector antenna was found to exhibit somewhat higher gain and larger F/B than corner reflector antennas. To verify the analysis results, W-type reflector antenna was fabricated and the radiation characteristics were measured. The measured results show good agreement with the calculated results.
Mode Identification of Resonant Frequencies for a Dielectric Loaded Circular Cylindrical Cavity
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 351~358
This paper describes the mode identification of resonant frequencies in dielectric loaded circular cylindrical cavity. To identify the mode of resonant frequencies, the calculated resonant frequencies were compared with the simulated ones in the air-filled circular cylindrical cavity by Microstripes EM simulator. With z-oriented magnetic field excitation, we could get only TE mode resonance, while all the modes including TM mode were observed with
-oriented magnetic field excitation. We could identify the modes with the two excitation methods. We applied the identification method to a dielectric loaded circular cylindrical cavity and compared these results with experimental ones. To certify the method, we traced resonance frequencies with varying the dielectric height. We observed that the resonance of
mode was changed dramatically while the variation of the
modes are relatively small.
Analysis of Corugated Surface Wave Antenna Using Hybrid MOM/UTD Method
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 359~367
The analysis of a surface wave antenna with the corrugated ground plane fed by a parallel-plate waveguide is considered. An equivalent theorem Is employed to subdivide the original problem into three regions for the simple analysis : one concerning the geometry inside the shorted parallel-plate(Internal region 1), one concerning the geometry of the corrugation(Internal region 2), and one concerning the geometry of the conducting wedge(External region). The hybrid method of moment(MOM)/uniform geometrical theory of diffraction(UTD) method is applied to analyze a corrugated surface wave antenna with the end-fire radiation. Our numerical results are very well matched with those of the previous experiment, better results are obtained when compared with those of the previous simple equivalent current approach. Also, we can obtain the parameters to design an effective end-fire corrugated surface wave antenna.
Design and Implementation of W-CDMA Transmitter for 2 GHZ Band
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 368~377
In this paper, the wide-band CDMA transmitter for 2 GHz band is designed and implemented. The CC-OQPSK implemented as ASIC has better spectral and power efficiency than the conventional QPSK system because it has constant envelope characteristics. Good harmonics rejection characteristics and gain of 20 dB are shown on the intermediate frequency stage using double-conversion scheme. The output power of two-stage RF amplifier is +2l.14 dBm in 1.9 GHz band. It is confirmed that the electrical characteristics of the transmitter satisfy with required the specification of the wide-band CDMA transmitter for 2 GHz band.
Incoherent Inverse Scattering of 3-Dimensional Underground Cavity in Lossy Medium
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 378~391
When the time-harmonic plane wave is incident upon a high-contrast spherical cavity in a lossy medium, the incoherent shadow intensity pattern is acquired by averaging out the multi-frequency intensities of the co-polarized total electric field calculated at the measurement plane perpendicular to the propagating direction of the incident wave in the forward direction. In the spherical rotational measurement configuration, an incoherent imaging of the spherical cavity is obtained via the back-projections of the incoherent shadow intensity pattern. This imaging method is validated by imaging an air sphere in the lossy medium of
= 2 and
= 0.001, 0.003 S/m and the conditions for obtaining better images are investigated.
A Study on the Effects of Various Portable Wireless Communication Equipments on the Medical Equipments
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 392~400
In this paper, the electromagnetic immunity of electronic medical equipments was tested by employing a standard test method for medical equipments. In addition, the electromagnetic interference to the medical equipments caused by four different types of mobile phones such as portable transceiver, analog, digital, and PCS cellular phones, have been studied. In this study, 16 medical equipments of 11 different types were investigated. There are a patient monitor, an infusion pump, a neonatal incubator and so on. In the case of the EMS test, the interferences were detected for seven medical equipments of four different types(53.3%) such as the patient monitor. For the two portable transceivers, 12 medical equipments of eight different models (75%) were affected. All medical equipments were satisfied with electromagnetic immunity by analog, digital and PCS cellular phones. The experiment results show that the malfunction of the electronic medical equipments is dependent on the frequency range and the electric field strength of the mobile phones.
The Analysis of Interference between IMT-2000 and GMPCS
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 401~411
IMT-2000 will provide worldwide mobile telecommunication services with the extended coverage areas such as polar regions and mountainous district. GMPCS also provides global telephony and paging services via satellite network at the altitude of 500~12,000 km. "Big LEO" which is one of the GMPCS systems using frequency above 1 GHz and IMT-2000 will share the frequency range of 1 to 3 GHz. Therefore, there exists possible interference between the two systems which can cause the performance degradation of both systems. In this paper, the radio-propagation modeling and interference analysis methods are presented and these methods are used to analyse the effect of the interference between IMT-2000 and GMPCS on system performance.rformance.
The Analysis of Scattering Characteristics of a Prime-focus Offset Parabolic Antenna with a Shaped Edge Structure
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 412~418
The scattering characteristics of a prime-focus offset-parabolic antenna are analyzed using UTD. First, ray tracing method is used to locate the shadow boundaries, and then UTD is utilized to evalute the far-zone scattered magnetic field pattern. The field components included in the UTD analysis are the reflected, edge diffracted and creeping waves. The effects of circular caps attached to both edges of a prime-focus offset-parabolic antenna are investigated by comparing the scattered magnetic field patterns with those of a knife edge parabolic reflector.
Microcellular Propagation Loss Prediction Using Neural Networks and 3-D Digital Terrain Maps
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 419~429
Identifying the boundary of the effective receiving power of waves is one of the most important factors for cell optimization. In this paper, we introduce a propagation loss prediction model which yields highly accurate prediction in very complex areas as Seoul where a mixture of many large buildings, small buildings, broad streets, narrow alleys, rivers and forests co-exist in an irregular arrangement. This prediction model is based on neural networks trained on field measurement data collected in the past. Using these data along with 3-D digital elevation maps and vector data for building structures, we extract the parameter values which mainly affect the amount of propagation loss. These parameter values are then used as the inputs to the neural network. Trained neural network becomes the approximated function of the propagation loss model which generalizes very well and can predict accurately in the regions not included in training the neural network. The experimental results show a superior performance over the other models in the cells operating in the city of Seoul.
Estimation and Analysis of Flutter Interference from Flights of an Airplane
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 430~439
In this paper, we have chosen Inchon International Airport as an area for estimating flutter interference to estimate and analyze the flutter Interference. We have proposed a method to overcome flutter interference. The simulation has been performed considering the received power of a direct wave, the height of an antenna, the ERP of a transmitting point, and the reflection coefficients as an estimation function for the flutter. From the simulation results, we have found that the flutter Interference from flights is very serious, and the degree of flutter interference can be changed according to the distance between an airplane and a transmitting point, the profile between transmitting and receiving points, and the reflection coefficients of an airplane.
Full Wave Analysis of EM Absorbers Using 3D Hybrid Finite Element Method
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 440~448
This paper describes a full wave analysis of the scattering from electromagnetic absorbers which can be approximated as infinite periodic structure using hybrid finite element method. By introducing fictitious boundaries, equivalent finite region is defined and proper boundary conditions of each boundary are obtained by Floquet theorem. Since higher-order Floquet modes are employed, the method presented in this paper can be readily applied to the periodic structure haying a relatively long period. To reduce difficulty in evaluating the surface integral, the normal component to the surface were represented with the tangential component to the surface. Comparisons of calculated results with analytical or published ones show the validation of the method.
Application Limits of Transmission Line Approximations for Design of Electromagnetic Absorbers
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 449~459
The scattering problems from electromagnetic absorbers can be greatly simplified using the transmission line approximations (TLA) and effective medium theory. This method has been widely used for the absorber design because of its very simple calculation and intuitional approach, while numerical analysis needs the tremendous computation requirements, This paper examined the accuracy and limitations originated by the intrinsic approximation limits of TLA by comparison with FEM results for various absorber design examples. It was found that the TLA result is valid when λ
2p, where λ is the wavelength of the interested upper frequency and p is the distance between two periodic cone arrays. Therefore, the electromagnetic absorbers having high material properties and big base-area commonly do not meet this condition, and the electromagnetic scattering from those absorbers must be evaluated by the numerical analysis in those cases.
Design of a 4-bit Digital Phase Shifter in Quasimillimeter Wave Band for Satellite Communication
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 10, issue 3, 1999, Pages 461~470
This paper presents the description of a 4-bit digital p-i-n diode phase shifter that was designed for quasimillimeter wave band satellite receiver to use in phased-array systems. 180
cells are designed in reflection type that consists of a 3-dB rat-race hybrid coupler, 45
cells are designed in loaded-line type to reduce the size of circuit and the number of diode to be used. The 4-bit phase shifter uses eight p-i-n diodes mounted in the microstrip circuit. The average insertion loss for the 16 phase states is 6.92dB over the 19.8~20.3 GHz band and maximum phase error is 6.2
at 20 GHz.