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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 8, Issue 6 - Dec 1997
Volume 8, Issue 5 - Oct 1997
Volume 8, Issue 4 - Aug 1997
Volume 8, Issue 3 - Jun 1997
Volume 8, Issue 2 - Apr 1997
Volume 8, Issue 1 - Mar 1997
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Performance Analysis of Hybrid DS/SFH-CDMA MFSK Signal with CCI Canceller and Convolution Code Techniques in Mobile Communication Multipath Interference Channels
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 3, 1997, Pages 221~231
This paper presents an analysis of a hybrid direct-sequence/slow frequency hopped code division multiple access(DS/SFH-CDMA) system employing noncoherent M-ary frequency shift keying(MFSK) modulation in a multiple m-distribution fading environment. Multipath interfer- ence(MPI) and multiuser interference(MUI) is taken into accout and the spectral efficiency is calculated for uncoded as well as simple channel coding systems. The predetection multipath CCI canceller in conjunction with convolution coding is employed for improving the bit error rate(BER) performance. The BER of noncoherent hybrid system is obtained using a Gaussian interference approximation. From the results, we know that the error performance more deteriorates as the depth of fading becomes deeper. The DS part of the modulation combats the multipath interference, whereas the FH part is a predetection against large multiuser interference. It is shown that, for the con- sidered types of a channel coding, the use of a predetection coding is still essential for obtained a satisfactory bit error performance. The results show that the capacity of the DS/SFG-CDMA MFSK communication system increases in proportion to the length of PN code sequence in the presence of AWGN and MUI. In m-distribution fading environment the capacity increases in proportion to the fading index. The capacity is increased and error performance is improved when the CCI Canceller and Convolution code technique are adopted, respectively. From the results, it is known that the error performance of
by adopting Canceller technique. Also convolutional coding technique is the improvement of error performance attains about
in code rate 1/2.
Development of Radio Frequency Identification System by Electromagnetic Induction
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 3, 1997, Pages 232~242
In this paper, we have designed an active radio frequency identification system solving the problems of moving transponder which is identification range expanding and low battery consuming of transponder. Developed radio frequency identification system is a bidirectional data transmission system which is composed of decoder data transmission of 120 kHz and transponder data carrier of 60 kHz which is a subharmonic frequency response with ASK modulation. The experimental results, designed system operating at 9600 bps, show good performances with detecting the 40 km/h moving transponder up to the range of 2 and 15
low consuming current.
The Development of Land Mobile Communication Microstrip Antenna Using Superstrate Effect
Hong-Min Lee ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 3, 1997, Pages 243~253
In land mobile communications, incident waves to mobile antenna com mostly from directions having low elevation angles about
down from the vertical plane. In order to receive this waves effectively, planar type antenna was fabricated and its characteristics were analyzed. This type of antenna is achieved using superstrate effect criteria which are derived for a nonzero radiation field extending down to the substrate layer surface plan. A small planar type microstrip antenna which can receive incident waves having low elevation angle was fabricated. Experimental results show that the band width of the fabricated antenna is 70 MHz at 1.2 GHz and have nonzero field down to the layer surface.
The Evaluation of the Characteristics of Electromagnetic Waves on CFRTP for Multimedia Instrument Applications
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 3, 1997, Pages 254~263
As the communication and electronic industry develops, it is important to study the electromagnetic shielding effectiveness (SE) of carbon fiber (CF) reinforced thermal plastics (CFRTP) against the electromagnetic (EM) radiation. In this paper the shielding effectiveness of CFRTP was measured experimentally in an electromagnetic shielding room. The resin ma- terials used were PC, PP, PEI, PMMA and PA. Experiments were carried out by using a copper box and a monopole antenna with a spectrum analyzer. From the experimental results it was found that CF was a good candidate as an electromagnetic shielding material. The sheilding effectiveness was found to be increased in the composite as the number of laminated layers of CF was increased. As the minor damage increased, the SE increased due to increasing of the plane density, transmitting thickness and reflected angle of the CF. Other characteristics of the SE depended on the material used for the resin matrix, distance of the antennas and the noise frequency band.
Analysis of Forced Resonance Characteristics of Electrically Small Dipole Antennas and Its Application to Measurements of Unknown Frequency
Ki-Chai Kim ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 3, 1997, Pages 264~272
This paper presents the analysis of forced resonance characteristics of electrically small dipole antenna loaded with external element and its application to measuring unknown frequencies. The method of moments with Galerkin's procedure is used to determine the current distribution of the antenna. To derive the determinantal equation of resonance lengths at a given frequency, small antennas with the reactance loaded can be treated as a two-port network. Numerical results show that the forced resonance of the electrically small dipole antenna loaded with reactance can be easily obtained by controlling the reactance for the series resonance as well as for the parallel resonance. It is demonstrated that the forced resonance characteristics can also be applied to the measurement of unknown frequencies.
Polarimetric Analysis of the Electromagnetic Waves Scattered from Random Surfaces-Full Wave Solutions
Lee, Bom-Son ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 3, 1997, Pages 273~288
In this work, the electromagnetic waves scattered from 2-dimensional random rough surfaces are characterized by the
Mueller matrix elements. The full wave solutions are used to compute these elements. The results of the full wave solutions for 1-dimensional random rough surfaces were shown to agree well with those of the experiment and the method of moments. The Mueller matrix elements are related to the like and cross polarized radar cross sections as well as to the relative phase of the vertically and horizontally polarized waves. The
Mueller matrix elements completely characterize electromagnetic scattering from target. The computed results of this paper can be useful to the field of active remote sensing or RCS.
Prediction of Diffraction Loss in Radio Channels
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 3, 1997, Pages 289~296
In this paper, several diffraction formulas are discussed and diffraction losses predicted from each formula for a wedge are compared with each other. Simulation results are also compared with measured ones. It turns out that in real situations, where many scatterers are located around a diffracting wedge, the prediction from the simple knife-edge formula for vertical polarization agrees well with the measured loss.
Design and Manufacture of a Small Inverted F Antenna in 1.9 GHz band
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 3, 1997, Pages 297~309
In this paper, A small inverted F Antenna with 1.9 GHz frequency band is studied theoretically, characterized by numerical analysis with computer and fabricated in order to use in the proximity sensor. Because of small space for antenna in proximity sensor, .lambda. /4 length plate and dielectric material are used to reduce the size of antenna and broaden the bandwidth. Finite ground body's affection is compensated by dielectric top loading effect which strengthen front direction power about 4 dB. Fabricated antenna is measured and the result is that resonant frequency is 1900.05 MHz, VSWR is 1.02, bandwidth is 194 MHz and input impedance is 50.45-j0.108 [ .ohm. ].
Prediction of Transmission Loss Due to Rain Scattering
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 3, 1997, Pages 310~317
Due to the congestion of the radio spectrum, frequency bands are shared among the communication systems. Therefore for the satisfactory operation we have to predict with reasonable accuracy the levels of interference that might exist among them. Inter- ference among the communication systems depends on many factors such as climate, radio frequency, time percentage of interest, distance and path topography. Interference due to rain scattering is the most important factorin Ghz frequencies. ITU-R offers the model related to interference due to rain scattering. In this paper the transmission loss due to rain scattering is predicted and compared with the measured results.