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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 11, Issue 8 - Dec 2000
Volume 11, Issue 7 - Oct 2000
Volume 11, Issue 6 - Sep 2000
Volume 11, Issue 5 - Aug 2000
Volume 11, Issue 4 - Jun 2000
Volume 11, Issue 3 - Apr 2000
Volume 11, Issue 2 - Feb 2000
Volume 11, Issue 1 - Jan 2000
Selecting the target year
Analysis of a Circular Microstrip Patch Antenna with Dielectric Superstrate using the Rigorous Probe Feed Model
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 859~867
In order to analyze the effect of a cover layer or radome for an antenna, the moment method is applied to the analysis of the circular microstrip patch antenna with dielectric superstrate fed by coaxial probe. The probe feed is modeled as a attachment mode method which can solve more exact analysis. In case of a ideal probe feed modeling, the probe self-impedance as well as the rapidly-varying patch current at the vicinity of the feed point was neglected. But a rigorous probe feed model which overcomes these deficiencies are developed, and used in the analysis of isolated circular patches. Measurements were performed to validate the numerical results. These are good agreement with each other.
A Wideband Circularily Polarized Antenna for GPS/GLONASS Comboned Receiver
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 868~875
GPS(Global Positioning System) is widely used in the navigation system, ITS(Intelligence Transportation System), and mobile communications. Recently, it is considered to combine the GPS receiver with the CLONASS for the improvement of performance and accuracy. In this paper, a wideband aperture-coupled patch antenna with circular polarization is designed and implemented for the use of CPS/GLONASS combined receiver. The measured characteristics of the manufactured antenna shows the - l5 dB bandwidth of 220 MHz and the axial ratio less than 2.1 dB, and it satisfies the requirements of the GPS/GLONASS antenna.
A New Method for Determination the Parasitic Extrinsic Resistances of MESFETs and HEMTs from the Meaured S-parameters under Active Bias
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 876~885
A new and simple method is presented for determining the parasitic resistances of MESFET and HEMT from the measured S-parameters under normal active bias without depending on additional DC measurements or iteration or optimization process. The presented method is based on the fact that the difference between source resistance(Rs) and drain resistance(Rd) can be obtained from the measured Z-parameters under zero bias condition. It is possible to define the new internal device including intrinsic device and 3 parasitic resistances by elimination the parasitic inductances and capacitances from the measured S-parameters. Three parasitic resistances are calculated easily from the fact that the real parts of Yint,11 and Yint,12 of intrinsic Y-parameters are zero theoretically and the relations between S-,Z-, Y-matrices. The calculated parasitic resistances using the presented method and successively calculated equivalent circuit parameters give modeled S-parameters which are in good agreement with the measured S-parameters up to 400Hz.
Surface Transfer Impedance Measurement of RF Cable according to IEC Standard 96-1
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 886~892
In this paper, surface transfer impedance measurement of RF cables according to IEC(International Electrotechnical Commission) Standard 96-1 is described and surface transfer impedance of a commercial RF cable is obtained from the measured voltage and scattering parameter with a triaxial fixture fabricated in the operating frequency range from 1 MHz to 30 MHz.
Design of 900 MHz CMOS Low Noie Amplifier
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 893~899
A 900 MHz low-noise amplifier(LNA) with a measured noise figure of 4.8 dB and an associated gain of 13.2 dB was fabricated in a 0.65
m CMOS. The inductive source architecture of offers the possibility of achieving the best noise performance. At 900 MHz, the fabricated LNA dissipates 39 mW from a single 3 V power supply including the bias circuitry and provides -26dB input return loss, -17 dB output return loss, and an input 1-dB compression level of -12 dBm.
Development of Broad-band Electromagnetic Wave Aborbers in Cut Corn and Cylinder Types
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 900~906
The remarkable progress of electronics and radio communications technology has made our life abundant. On the other hand, the countermeasure of EMl/EMC becomes more important socially according to the increased use of electromagnetic waves. It had been required that the absorbing ability of an electromagnetic wave absorber is more than 20 dB, the bandwidth of which is required through 30 MHz to 1,000 MHz for satisfying the international standard about an anechoic chamber for EMl/EMS measurement. From November of 1998, however, the CISPR11 has accepted the extended frequency band to 18 GHz in the bandwidth of EMI measurement. In this paper, we proposed the cut corn type and cylinder type absorbers satisfying the above requirments and carried out broadband design using the equivalent material constants method.
Wave Attenuator for Human Brain Protection to be et Wireles Phone Hand Set by Corrugate Ceramic Chip
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 907~913
Design and Fabrication of a Simple Orthogonal Mode Transduce with Good Iolation
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 914~919
A simple orthogonal mode transducer(OMT) for X-band has been proposed in this paper. This OMT is designed such that a polarized wave can be guided in a direction using several thin guiding posts, and the other orthogonally polarized wave can be guided in the other direction using other thin guiding posts. The OMT consists of a T-shaped waveguide section with guiding posts, two tapering waveguide arms, and has three flanges for connection with two adapters and an antenna. The optimum numbers and the optimum positions of the guiding posts were obtained numerically using the HFSS CAD tool. The isolation between two polarizations in a manufactured OMT is higher than 42.8 dB and the reflection from the OMT is lower than -17.5 dB at the frequency band of 9.5 GHz
Simple Miniaturization Method of a Microstrip Patch Antenna
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 920~928
In this paper, using newly proposed size reduction technique, the aperture coupled microstrip patch antenna for a repeater system in a mobile communication cellular band (824~849 MHz) is developed with a wide bandwidth, small size, light weight, and low cost. The resonant frequency of microstrip antennas is related to the electric field distribution of the radiating patch. The field strength of
mode of a rectangular patch antenna is strongest at each of the extremities of the radiating patch, but negligible at center. Therefore, the size of a patch antenna can be effectively minimized by inserting the narrow rectangular dielectric into just under the edges of the resonant Patch. This Paper also proposes the bandwidth improvement technique by using under-coupling technique with a tuning stub. The VSWR is less than 1.5 : 1 for the whole cellular band. The simulation tool was HFSS, Agilent Technologies, Inc.
RCS Prediction of Complex Targets
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 929~938
A summary of the development and verifications of a computer code being developed at Pohang University of Science and Technology (POSTECH) for calculating the radar cross section(RCS) of complex targets is presented. The complex targets are modeled in terms of patches and wedges. This code utilizes physical optics, physical theory of diffraction and shooting and bouncing rays method to calculate the RCS of complex targets. For the verification of the RCS prediction code, a simple-shaped scale-model was manufactured and the RCS was measured at the POSTECH compact range. The obtained RCS was processed to give frequency-domain RCS patterns and ISAR images. The predicted RCS shows good agreement with measured one. The RCS prediction methods presented here are applicable to stealth design and target recognition.
Iterative Teconstruction of a Cylinder Buried in the Lossy Half Space
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 939~945
A cylindrical object buried in the lossy half space is reconstructed from the measured scattered fields above the lossy half space. The position, the size and the medium parameters i.e. relative dielectric constants and conductivity of the buried object as well as the medium parameters of the background lossy half space are obtained from the scattered fields by using the iterative inversion method and the optimization hybrid algorithm combining the genetic algorithm and the Levenberg-Marquardt algorithm. Illposedness of the inversion due to the measurement errors in the scattered fields are regularized by filtering out the evanescent modes in the spatial frequency spectrum domain.
Characteristics of DGS Transmission Line and Influence of Lumped Elements on DGS
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 946~951
In this paper, we showed the characteristic of transmission line with DCS (Defected Ground Structure), which is etched on the metallic ground plane. And we extracted the equivalent element value of DGS section. Effects of a lumped element placed on DGS section were investigated by employing DGS of dumbbell shape and parallel resonator with DGS. Chip type resistor, inductor, and capacitor were chosen as lumped elements for experiments. Experimental results show that the Q-factor and resonant frequency of the proposed DGS section can be controlled directly by using the external lumped element.
Integrated Micro-Mechanical Switches for RF Applications
Park, Jae Y. ; Kim, Geun H. ; Chung, Ki W . ; Jong U. Bu ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 952~958
Design of Low Noise Frequency Synthesizer for B-WLL RF Tranceiver
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 959~968
In this paper, a low phase noise frequency synthesizer used to TX local oscillator in BWLL RF tranceiver is presented. The phase-locked stable 25GHz-band frequencies in BWLL TX LO are obtained by using 2 GHz baseband frequency synthesizer, sixth-harmonic frequency multiplier and frequency doubler at 12 GHz band frequency input. The 25 GHz band frequency synthesizer presented in this paper has 3-output frequencies at 24.92 GHz, 25.10 GHz, 25.26 GHz. At 24.92 GHz frequency the synthesizer has 0.44 dBm output power and shows -87.93 dBc/Hz(a 10 KHz), -109.54 dBc/Hz (a100 KHz) phase noise characteristics .
Novel K/Ka Bandpass Filters using LIGA Micromachined Process
Park, K. Y. ; Park, J. Y. ; Choi, H. K. ; Lee, J.C. ; Lee, B. ; Kim, J. H. ; Kim, N. Y. ; Park, J. Y. ; Kim, G. H. ; Kim, D. W. ; Bu, J. U. ; Chung, K. W. ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 969~975
New class of three dimensional (3-D) micromachined microwave planar filters at K and Ka-band are presented using LIGA micro-machined process. The K-and Ka-band filters show wide bandpass characteristics of~36% and ~39% with the insertion loss 1.26dB at 19.11GHz and 1.7dB at GHz, respectively. These filters can be applicable in high power MMIC of MIMIC.
FDTD 방법을 이용한 3T MRI용 RF 코일의 해석
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 976~983
In this paper, Bridcage type RF coils used widely as RF coils for MRI and its applicable type, spiral type RF coil are analyzed and designed using FDTD method. In low tesla (IT, 1.5T) MRI system, several tools have been used for the analysis and design of the RF coils for MRI. This includes, so-called, LC equivalent circuit method for predicting the resonance frequency of the coil and the Biot-Savart law to determine the field distribution within the coil. Both of the circuit analysis and Biot-Savart law are low frequency techniques. Therefore, at high frequency applications, the circuit model approximation breaks down because the coil geometry is a significant fraction of the wavelength. In this paper, we analyzed and designed RF coils for 3T MRI using FDTD method. This method is a full wave analysis and very accurate at low and high frequencies. Also, this RF coils are actually fabricated and FDTD models of RF coils for MRI are proven.
Microstrip 3-dB Tapered Array Antenna with Wide Detection Range at 35 GHz
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 984~989
A microstrip patch array designed at 35 GHz is described for use in the detection of the position of moving targets. To obtain wide detection range, the array is arranged to give a narrow beamwidth in the elevation plane and a wide beamwidth on the azimuth plane. This can be achieved by aligning the electric field plane of each element to the array axis. Employing a 3 dB-tapered feed network, the array has a side lobe level of less than -20 dB and wider azimuth beam width of 12.8
A Gap Coupled NRD-Guide Filter Designed with an Equivalent Circuir Model of Evanescent Waveguide
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 990~995
As the interest in the millimeter wave frequency (30 ~300 GHz) increases, Nonradiative Dielectric (NRD) guide is being more attractive due to its low loss characteristics. Most of millimeter wave components, which can be realized with waveguide, can also be realized with NRD guide since NRD guide has similar dispersion characteristics and field patterns to waveguide. Previously, Variational Method was applied to the gap discontinuity problem to design a gap-coupled NRD bandpass filter. In this paper, the design procedure was simplified by replacing the air gap region with an equivalent circuit model of an evanescent waveguide using the fact that the NRD guide has a similar structure with a dielectric-filled metal waveguide. Prior to applying this design method to the bandpass filter of millimeter wave frequency range, a bandpass filter of which center frequency is 10 GHz(3-Pole, 0.1 dB ripple, 2% fractional bandwidth) was designed and fabricated. The measured result agrees with one simulated with HFSS within an error range of a fabrication.
The Design of the Broadband ceramic Dielectric Sntenna for PCS and IMT-2000 Dual Band Application
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 996~1005
This paper proposed a novel broadband ceramic dielectric antenna by improving the conventional broadband technique that very high permittivity material is attaching to one side of low permittivity material. The broadband ceramic dielectric antenna can be designed by using our proposed method, and it overcomes the disadvantage of narrow bandwidth problem. For the proposed ceramic dielectric antenna, a 10 dB return-loss bandwidth of 33.9% has been achieved. The measurement and numerical results(Finite Element Method) are performed and confirmed to a good agreement with each other. The proposed ceramic dielectric antenna is designed and implemented to extend enough the coverage of dual band (PCS+IMT-2000).
Hemisphere Type Lunegerg Lens Antenna with a Reflector
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 11, issue 6, 2000, Pages 1006~1014
Hemisphere type Luneberg lens antenna with a reflector(frequency : 9.375 GHz, -3 dB beam width 6
, diameter 30.3 cm(about 10 A), which is miniaturized and lightweightized by attaching a reflector on a section of half the Luneberg lens antenna, is designed and fabricated on the basis of Luneberg lens antenna from which easy beam pointing is acquired only by movement of 1st radiator. Measurement shows -3dB beamwidth is 6.1
in case of E-plane and 5.5
in case of H-plane. These are good agreements with expected value. Gain of this antenna is 26dBi(Aperture efficiency for uniform distribution :
= 44.97%) which is greater than that of 1st radiator(Rectangular microstrip antenna) by 20.4 dB. And, after calculating the approximated pattern of the 1st radiator, far-field pattern, whose source is the second aperture source farmed from the approximated pattern of the 1st radiator is computed. Comparing this far-field pattern with the expected pattern, a (relatively) good agreement is observed. Circular polarization Luneberg lens antenna is also manufactured by making 1st radiator so that it has the characteristics of LHCP and RHCP radiation. The results are as followings : -3 dB beamwidth 5.8
, side lobe level -15.3 dB, isolation between LHCP and RHCP radiation 2543, axial ratio 2 dB bandwidth about 1.4 GHz(14.9%).