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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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The K-band Oscillator using Split Ring Resonator
Han-Kee Joo ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 2, 1997, Pages 107~115
In this paper, a 23 GHz push-push oscillator was designed and fabricated for 23 GHz point-to-point communication using split ring resonator. The split ring resonator was equivalent circuit and numerical method of MPIE(Mixed Potential Integral Equation). The analysis of split ring resonator which coupled between microstrip lines was carried out with transmission-mode using this results. The fabricated oscillator showed the output power of 4 dBm, the 1'st harmonic suppression of -20 dBc, the 3rd harmonic suppression of -34 dBc, a SSB phase noise of -109 dBc / Hz at 1MHz offset frequency from the carrier was achieved and 1.4 percents efficiency at 23 GHz. The experimental outputs were in good results with the theoretical and simulated results.
Adaptive Antenna Array for DOA Estimation Utilizing Orthogonal Weight Searching
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 2, 1997, Pages 116~125
This paper presents a novel method, entitled Orthogonal Weights Searching(OWS), for the Direction-Of-Arrival(DOA) estimation. Utilizing the modified Conjugate Gradient Method(MCGM), the weight vector which is orthogonal to the signal subspace is directly computed from the signal matrix. The proposed method does not require the computation of the eigenvalues and eigenvectors. In addition, the new technique excludes the procedure for the detection of the number of signals under the assumption that the number of weights in the array is greater than the number of input signals. Since the proposed technique can be performed independently of the detection procedure, it shows a good performance in adverse signal environments in which the detection of the number of array inputs cannot be obtained successfully. The performance of the proposed technique is compared with that of the convectional eigen-decomposition method in terms of angle resolution for a given signal-to-noise ratio(SNR) and a required amount of computations.
A New Fading Estimation Method for PSAM in Digital Land Mobile Radio Channels
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 2, 1997, Pages 126~136
When we apply the spectrally efficient quadrature amplitude modulation(QAM) to mobile communications, it is necessary to estimate and compensate the channel charac- teristics. In this paper, a new type fading estimation method for PSAM using sinc function is presented. Gaussian interpolation method has a drawback that the performance degrades rapidly if pilot symbol period increases even though pilot sysbol period is less than Nyquist sampling rate. The Wiener filter method does not degrade until pilot symbol period is equal to the Nyquist sampling rate. It is difficult for Wiener filter method to be applied to real system because autocorrelation function of channel gain, Doppler frequency and SNR(signal to noise ratio) must be known to optimize the filter coefficients. But proposed method has a similar performance to the Wiener filter method, and does not need to know the autocorrelation function of channel gain, the doppler frequency and SNR. Therefore the proposed method cna be applied to real system easily.
Analysis of Electromagnetic Coupling to an Infinitly Long Wire through a Slot in an Infinite Conducting Plate
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 2, 1997, Pages 137~150
The problem of electromagnetic coupling into a thin conducting wire through a slot in an infinite conducting is analyzed by use of MPIE(mixed potential integral equation) and two- dimensional moment method using subsectional(rooftop) basis functions. The equivalent circuit is derived using a center-repesentation method which is valid in a narrow slot case. The equi- valent magnetic currents on the slot and the induced currents on the wire are caculated respec- tively, for the TM wave is incident upon the slot with arbitrary angle of incidence. The theoretical transmission coefficients of transmission line which is composed of thin-wire and infinite conducting plate with a narrow slot are compared and found to be in good agreement with experimental results.
The Study on the Performance of DS/CDMA with a Suppressed Pilot Channel in Mobile Satellite Communication System
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 2, 1997, Pages 151~160
In this paper, we have carried out the DS/CDMA with a suppressed pilot channel, which is used in receiving coherently with Rake diversity and in synchronizing the chip timing, in the mobile satellite communication. Also, we have investigated the envelope variation of a shadowed Rician fading simulator, and analyzed the error performences of DS/CDMA in the mobile satellite communication. The results showed that the error performance in the Heavy shadowing environment might be degraded more than in the Rayleigh fading environment since the fading envelopes in the former environment are varied randomly compared with those in the latter environment. And the performence of DS/CDMA system could be improved about 10 dB compared with that of narrowband QPSK system. In conclusion, DS/CDMA with a suppressed pilot channel had the best performance in the case of the suppressed pilot channel to transmission power ratio
=-8 dB, the number of complex delay profiles
=32, and using these values, the error performance of DS/CDMA in Light shadowing environment was identical to the ideal QPSK error performance.
Analysis of Electromagnetic Scattering by a Perfectly Conducting Strip Grating on Dielectric Multilayers
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 2, 1997, Pages 161~172
In this paper, electromagnetic scattering by a perfectly conducting strip grating on dielectric multilayers is analyzed for the normalized reflected and transmitted power by applying the Fourier-Galeakin moment method. The induced current density is expanded in a series of multiplication of chebyshev polynomials of the first kind and functions with appropriate edge boundary condition, the continuous condition of electromagnetic field is applied in the boundary planes. The confirm the validity of the proposed method, the nor- malized reflected and transmitted power obtained by varying the relative permittivity and thickness of each dielectric layers are evaluated and compared with those of the existing numerical method and a paper, and then the numerical results in this paper are in good agreement with those of the existing numerical method and the paper. The sharp variation position in the geometrically normalized reflected and transmitted power can be moved by the incident angle, grating period, and the relative permittivity and thickness of the dielectric multilayers, these sharp variation points which are called the Wood's anomaly of the Geome- trically normalized reflected power are observed as a main factor when the reflected powers of the higher order mode are transitted between propagating and evanescent modes, and the local minimum positions are slightly moved to the left hand direction in which grating period is getting small according to the increase of the relative permittivity of dielectric layers.
Performance Improvement of MFSK-MDPSK/DS-CDMA System Employing MRC Diversity Techniques and Convolution Coding Techniques in Nakagami Fading Environment
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 2, 1997, Pages 173~184
In most DS-CDMA systems, the modulation scheme used is a simple one. In this paper, the error performance of DS-CDMA system employing a MFSK-MDPSK combined moulation techniques in adopting MRC diversity reception and convolution coding technique are evaluated. The obtained result show that the error performance of MFSK-MDPSK/DS-CDMA system in Nakagami fading environments is improved by increasing the number of diversity branch and coding gain. Also the power efficiency and bandwidth efficiency combined system in MFSK/ DS-CDMA, MDPSK/DS-CDMA are better than conventional MFSK-MDPSK/DS-CDMA systems.
Comparison and Analysis of Techniques for Achieving Azimuth Resolution of Imaging Radar
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 2, 1997, Pages 185~196
By considering the definition and application of resolution as well as the concept and theory of SAR, the essential contents of the SAR design and analysis are described. This paper is to compare and analyze the resolution performance capability of three techniques for achieving azimuth resolution such as the real aperture, the unfocused and the focused techniques, through the simulation. Simulation is performed to make the restricted conditions for the unfocused technique that can be implemented by the less commputing load of signal processingand the lower cost. Through the mission analysis, the use of SAR image can be applied for estimation of whole situation at the regional area in the field of military demands for tactical purpose as well as civilian demands for the damage of disaster. RPV and sall or medium aircraft are selected to carry the SAR for these purposes and the proper resolution turns ou 5~15 m. The trade-off study of variables through the simulations results in the proper conditions such that range is less 3, 000 m, Wavelength is 1~10 m, and the raw signals and results processed by three techniques for two point targets are exhibited undr such conditions. Therefore, at some points, the result of this paper si proposed for useful applications of unforcused technique in the restricted conditions except the identification of the small target at a long range re- quired for high resolution.
An Improvement of BER Performance for Coded 16-QAM over Mobile Communication Channel by Asymmetric Signal Constellation
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 2, 1997, Pages 197~206
The purpose of this paper is to propose an improvement method of BER for coded 16QAM over Rayleigh fading channel. To overcome the BER degradation due to the fading under mobile communication, we apply trellis coded modulation technique which is efficient to get a coding gain without the expansion of bandwidth. Especially, to minimize the burst error which are the main factor of the BER degradation for mobile communication systems, we apply interleaving/deinterleaving method to the studying system. Also we apply asymmetric signal mapping methods to this TCM scheme. From the computer simulation, BER performance of asymmetric case has achieved about 1 dB improvement of about
, compared to the traditional symmetric case.
Statistical Analysis of Radio Frequency Noise Spectrum in Urban Areas
Joong-Geun Rhee ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 8, issue 2, 1997, Pages 207~213
Measurements of the RF(Radio Frequency) noise spectrum from 30 MHz to 18 GHz have been conducted at 21 urban areas in Korea in 1994 and 1995. Statistical analysis of the data measured seasonally, day and night, at each different point has been performed. The results of the computer analysis on APD, NAD, and ACR using GUI(Graphical User Interface) program show that the radio noise environments vary little in spring, summer, and winter, while the noise level increases a little in fall. In addition, the noise level of the night time shows a little higher than that of the day time.