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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of electromagnetic engineering and science
Journal Basic Information
Journal DOI :
The Korean Institute of Electromagnetic Engineering and Science
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Volume & Issues
Volume 4, Issue 4 - Dec 2004
Volume 4, Issue 3 - Sep 2004
Volume 4, Issue 2 - Jun 2004
Volume 4, Issue 1 - Mar 2004
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Complex Permittivity Measurement of Reference Liquids using the Slotted Coaxial Line at Mobile Communication Frequencies
Kim, Jeong-Ho ; Gimm, Youn-Myoung ;
Journal of electromagnetic engineering and science, volume 4, issue 3, 2004, Pages 97~101
Complex permittivities of reference liquids were measured by a liquid holder of slotted coaxial line with a movable probe at mobile communication frequencies. The validity of the liquid measurement system was checked by experimental tests with the reference liquids proposed in IEEE Std. 1528-200X or IEC 106/61/CDV.
Rotation-Free Transformation of the Coupling Matrix with Genetic Algorithm-Error Minimizing Pertaining Transfer Functions
Kahng, Sungtek ;
Journal of electromagnetic engineering and science, volume 4, issue 3, 2004, Pages 102~106
A novel Genetic Algorithm(GA)-based method is suggested to transform a coupling matrix to another, without the procedure of Matrix Rotation. This can remove tedious work like pivoting and deciding rotation angles needed for each of the iterations. The error function for the GA is simply formed and used as part of error minimization for obtaining the solution. An 8th order dual-mode elliptic integral function response filter is taken as an example to validate the present method.
A 900 MHz VCO Having 7-dB Phase Noise Improvement at 100 kHz Offset
Lee, Ja-Yol ; Kang, Jin-Young ; Oh, Seung-Hyeub ;
Journal of electromagnetic engineering and science, volume 4, issue 3, 2004, Pages 107~112
In this paper, the phase noise of 900 MHz VCO is improved using modified strip line square ring resonator. In order to demonstrate the phase noise improvement of the proposed VCO, the same circuit was manufactured using shorted-circuit resonator. In condition of the same bias current, the phase noise of the proposed VCO with modified square ring resonator is suppressed by 7 dB as - 103 dBc/Hz at 100 kHz offset compared to the conventional VCO with short-circuit resonator. From the proposed VCO, we achieved output power of - 4.8 dBm, harmonics suppression of 16 dB, and tuning bandwidth of 100 MHz. The proposed VCO consumed 5 mA at 3 V, and its size is 1.2 cm
A New Measurement Technique on Inherent-Ring-Resonance Frequency and Effective Loss-Tangent using Ring Filters
Ahn, Hee-Ran ; Lee, Kwyro ;
Journal of electromagnetic engineering and science, volume 4, issue 3, 2004, Pages 113~118
As an application of ring filters, a new and simple method to determine an inherent-ring-resonance frequency is introduced. The ring filter consists of a ring and two short stubs. They are connected at 90
points of the ring and the ring filter may be seen in such way that two filters are connected in parallel. Therefore, if the two powers of the two filters are out-of-phase at the output, the power excited at the input can not be delivered. That can be done by making difference in length of the two short stubs, and when a certain condition is satisfied, a frequency exists where all the excited power is reflected. That is the very inherent-ring-resonance frequency. In the lossless case, the return loss with the condition reaches 0 dB at the inherent-ring-resonance frequency but does not with conductor, dielectric losses and so on. Therefore, the effective loss tangent at a frequency of interest may be obtained correctly. To verify the method, two ring filters have been fabricated in microstrip lines and the measured results show good agreement with the predicted ones.
Measurement of Rain Induced Attenuation using the Beacon Signal of Koreasat-3
Choi, Dong-You ; Park, Chang-Gyun ;
Journal of electromagnetic engineering and science, volume 4, issue 3, 2004, Pages 119~123
This paper presents here the results of the measurements of rain-induced attenuation in the vertically polarized signal propagating at 12.2525 GHz during some rain events, which occurred in the rainy wet season of the year 2001 at Yong-in, Korea(temperate climate). The attenuation measured experimentally was compared with that obtained using the International Telecommunication Union Radio Communication Sector(ITU-R) model, the SAM model and the Global model. In this paper, measured results are in good agreement with the ITU-R prediction.
Printed Folded Antenna for Dual-Band WLAN Operations
Chae, Gyoo-Soo ; Cho, Young-Ki ;
Journal of electromagnetic engineering and science, volume 4, issue 3, 2004, Pages 124~127
A novel printed inverted-F antenna for dual-band WLAN is presented. The proposed design is based on the folded quarter-wave antennas, which have a conductor plate having two arms. An extremely thin prototype antenna is fabricated according to the simulation result. The obtained antenna can perform in IEEE802.11a, b(2.4～2.484 GHz and 5.15～5.35 GHz bands) and be adopted for laptop applications. All the measurements are performed in the actual test fixture.
Circular Polarization Diversity in Indoor Wireless Mobile Environments
Ha, Deock-Ho ; Ko, Yeon-Hwa ; An, Jae-Sung ; Kim, Tai-Hong ;
Journal of electromagnetic engineering and science, volume 4, issue 3, 2004, Pages 128~136
In this paper,. with the aim of achieving the expected performance improvement for a polarization diversity system, we analyzed two-branch polarization diversity at the receiving end of a mobile link which a transmitter emits circularly polarized wave. In this analysis, to calculate the correlation coefficient considered by XPD(cross polarization discrimination) between the two received signals, a simple theoretical model of circular polarization diversity is adopted. From the analysis results, it is clearly seen that the correlation coefficient of circular polarization diversity evaluated by the XPD is less than that of conventional linear polarization diversity. And also, we designed and implemented a circular polarization diversity system with micro-strip antenna. By using the circular polarization diversity system, we analyzed the measured data in indoor NLOS(Non-Line-Of-Sight) environments. From this analysis results, it is also clearly seen that the diversity effect of circular polarization diversity system shows better performance compared to the conventional linear diversity system by about 3 dB high.
A 5-GHz Band CCNF VCO Having Phase Noise of -87 dBc/Hz at 10 kHz Offset
Lee, Ja-Yol ; Lee, Sang-Heung ; Kang, Jin-Young ; Kim, Bo-Woo ; Oh, Seung-Hyeub ;
Journal of electromagnetic engineering and science, volume 4, issue 3, 2004, Pages 137~142
In this paper, we present a new current-current negative feedback(CCNF) differential voltage-controlled oscillator (VCO) with 1/f induced low-frequency noise suppressed. By means of the CCNF, the 1/f induced low-frequency noise is removed from the proposed CCNF VCO. Also, high-frequency noise is stopped from being down-converted into phase noise by means of the increased output impedance through the CCNF and the feedback capacitor
. The proposed CCNF VCO represents 11-dB reduction in phase noise at 10 kHz offset, compared with the conventional differential VCO. The phase noise of the proposed CCNF VCO is measured as - 87 dBc/Hz at 10 kHz offset frequency from 5.5-GHz carrier. The proposed CCNF VCO consumes 14.0 mA at 2.0 V supply voltage, and shows single-ended output power of - 12 dBm.