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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 6, Issue 4 - Dec 2006
Volume 6, Issue 3 - Sep 2006
Volume 6, Issue 2 - Jun 2006
Volume 6, Issue 1 - Mar 2006
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Piezo-controlled Dielectric Phase Shifter
Jeong Moon-Gi ; Kim Beom-Jin ; Kazmirenko Victor ; Poplavko Yuriy ; Prokopenko Yuriy ; Baik Sung-Gi ;
Journal of electromagnetic engineering and science, volume 6, issue 1, 2006, Pages 1~9
A sandwich structure of dielectric material and air gap inside a rectangular waveguide is proposed as a fast electrically tunable low-loss phase shifter. As the dielectric material is shifted up and down by piezoelectric actuator and, thereby, the thickness of air gap is changed, the effective dielectric constant of the sandwich structure is varied. Phase shifters based on the sandwich structure with different dielectric materials showed phase shift of
at X-band as the thickness of air gap varied up to
. The idea can be extended toward low-loss millimeter wave phase shifters since modem microwave ceramics have been developed to show very low dielectric loss
RAKE Receiver for Time Division Synchronous CDMA Mobile Terminal
Xiao Yang ; Lee Kwang-Jae ; Lee Moon-Ho ;
Journal of electromagnetic engineering and science, volume 6, issue 1, 2006, Pages 10~17
For the sake of the potential ability of overcoming interference in TD-SCDMA(time division-synchronous code division multiple access) systems, pilot signal is adopted, but the presented TD-SCDMA protocol has not considered the Rake technique for their mobile terminals. This paper developed a RAKE receiver algorithm and an implementation circuit, which make use of the pilot signal in the burst structure of the TD-SCDMA base station to estimate main channel parameter(channel delays) in the downlink of TD-SCDMA wireless network. The algorithm can reduce multipath interference for the mobile units in multiusers' case. Theoretic performance analysis presented in the paper and computer simulations show that there is a range of BER for Rake receiver and confirm that the proposed RAKE receiver algorithm achieved a better performance under multipath fading propagation and multiusers conditions.
An MMIC Broadband Image Rejection Downconverter Using an InGaP/GaAs HBT Process for X-band Application
Lee Jei-Young ; Lee Young-Ho ; Kennedy Gary P. ; Kim Nam-Young ;
Journal of electromagnetic engineering and science, volume 6, issue 1, 2006, Pages 18~23
In this paper, we demonstrate a fully integrated X-band image rejection down converter, which was developed using InGaP/GaAs HBT MMIC technology, consists of two single-balanced mixers, a differential buffer amplifier, a differential YCO, an LO quadratue generator, a three-stage polyphase filter, and a differential intermediate frequency(IF) amplifier. The X-band image rejection downconverter yields an image rejection ratio of over 25 dB, a conversion gain of over 2.5 dB, and an output-referred 1-dB compression power
of - 10 dBm. This downconverter achieves broadband image rejection characteristics over a frequency range of 1.1 GHz with a current consumption of 60 mA from a 3-V supply.
The Circular Polarization Diversity Effect Considering XPD Factor in an Indoor Radio Propagation Environment
Ahn Je-Sung ; Ha Deock-Ho ; Cho Pyung-Dong ;
Journal of electromagnetic engineering and science, volume 6, issue 1, 2006, Pages 24~29
In this paper, we analyzed new two-branch polarization diversity at the receiving end of a mobile link which a transmitter emits circularly polarized wave. To analyze the correlation coefficient considered by XPD(Cross Polarization Discrimination) between the two received signals, a simple theoretical model of circular polarization diversity is adopted and experimental measurements are also conducted. From both theoretical and measurement results, it can be seen that the proposed circular polarization diversity scheme is more effective than that of the conventional linear polarization diversity.
Optimized Phase Noise of LC VCO Using an Asymmetrical Inductance Tank
Yoon Jae-Ho ; Shrestha Bhanu ; Koh Ah-Rah ; Kennedy Gary P. ; Kim Nam-Young ;
Journal of electromagnetic engineering and science, volume 6, issue 1, 2006, Pages 30~35
This paper describes fully integrated low phase noise MMIC voltage controlled oscillators(VCOs). The Asymmetrical Inductance Tank VCO(AIT-VCO), which optimize the shortcoming of the previous tank's inductance optimization approach, has lower phase noise performance due to achieving higher equivalent parallel resistance and Q value of the tank. This VCO features an output power signal in the range of - 11.53 dBm and a tuning range of 261 MHz or 15.2 % of its operating frequency. This VCO exhibits a phase noise of - 117.3 dBc/Hz at a frequency offset of 100 kHz from carrier. A phase noise reduction of 15 dB was achieved relative to only one spiral inductor. The AIT-VCO achieved low very low figure of merit of -184.6 dBc/Hz. The die area, including buffers and bond pads, is
A Two-Element Circularly-Polarized Antenna Array for UHF-Band RFID Reader Applications
Park Joung-Min ; Kim Yun-Mi ; Ahn Bierng-Chearl ; Park Chan-Sik ; Cha Eun-Jong ;
Journal of electromagnetic engineering and science, volume 6, issue 1, 2006, Pages 36~46
In this paper, we present a two-element circularly-polarized antenna array for UHF-band RFID reader applications. The antenna element in the array is a comer-truncated rectangular patch placed on a thick plastic-foam dielectric. The patch is fed on one of its edges by a microstrip line printed on a separate thin substrate. The array antenna is fed by a microstrip power divider. Parametric studies on the patch are carried out, from which an optimum design of a single antenna element is derived. The element spacing and the feed network of the array are investigated. A commercial electromagnetic software is employed in the analysis and design of the antenna. The designed array is fabricated and tested. Measurements show good performance characteristics of the fabricated antenna: a 11.2-dBi gain, a reflection coefficient of - 14 dB, an axial ratio less than 3 dB over 3-dB beamwidths of 40 and 60 degrees on two principal planes.
Effects of Size and Permittivity of Rat Brain on SAR Values at 900 MHz and 1,800 MHz
Hyun Jong-Chul ; Oh Yi-Sok ;
Journal of electromagnetic engineering and science, volume 6, issue 1, 2006, Pages 47~52
The objective of this study is to evaluate the effects of size and permittivity on the specific absorption rate(SAR) values of rat brains during microwave exposure at mobile phone frequency bands. A finite difference time domain (FDTD) technique with perfect matching layer(PML) absorbing boundaries is used for this evaluation process. A color coded digital image of the Sprague Dawley(SD) rat based on magnetic resonance imaging(MRI) is used in FDTD calculation with appropriate permittivity values corresponding to different tissues for 3, 4, 7, and 10 week old rats. This study is comprised of three major parts. First, the rat model structure is scaled uniformly, i.e., the rat size is increased without change in permittivity. The simulated SAR values are compared with other experimental and numerical results. Second, the effect of permittivity on SAR values is examined by simulating the microwave exposure on rat brains with various permittivity values for a fixed rat size. Finally, the SAR distributions in depth, and the brain-averaged SAR and brain 1 voxel peak SAR values are computed during the microwave exposure on a rat model structure when both size and permittivity have varied corresponding to different ages ranging from 3 to 10 weeks. At 900 MHz, the simulation results show that the brain-averaged SAR values decreased by about 54 % for size variation from the 3 week to the 10 week-old rat model, while the SAR values decreased only by about 16 % for permittivity variation. It is found that the brain averaged SAR values decreased by about 63 % when the variations in size and permittivity are taken together. At 1,800 MHz, the brain-averaged SAR value is decreased by 200 % for size variation, 9.7 % for permittivity variation, and 207 % for both size and permittivity variations.
Parametric Studies for the Optimum Design of a Hexagonal Plate Monopole Antenna
Park Seong-Bae ; Park Joung-Min ; Ahn Bierng-Chearl ; Kim Kyung-Seok ;
Journal of electromagnetic engineering and science, volume 6, issue 1, 2006, Pages 53~61
In this paper, we present parametric studies for the optimum design of a hexagonal plate monopole antenna. The dependence of the antenna performance on various geometric parameters is investigated using a commercial electromagnetic software, from which an optimum design of a hexagonal plate monopole antenna is derived. Guidelines for determining initial parameter values are given. The diameter of the circular ground plane is minimized tlo 1/5 wavelength at the lowest operating frequency. The antenna impedance matching is controlled by adjusting the gap between the plate and the ground plane, the plate base width, and the base bevel angle. The antenna proposed in. this paper shows a reflection coefficient less than -10 dB and a
dBi gain over
Design of Power Plane for Suppressing Spurious Resonances in High Speed PCBs
Oh Seung-Seok ; Kim Jung-Min ; Yook Jong-Gwan ;
Journal of electromagnetic engineering and science, volume 6, issue 1, 2006, Pages 62~70
This paper presents a new power plane design method incorporating a single geometry derived from a unit cell of photonic bandgap(PBG) structure. This method yields constantly wide suppression of parallel plate resonances from 0.9 GHz to 4.2 GHz and is very efficient to eliminate PCB resonances in a specified frequency region to provide effective suppression of simultaneous switching noise(SSN). It is shown that with only two cells the propagation of unwanted high frequency signals is effectively suppressed, while it could provide continuous return signal path. The measured results agree very well with theoretically predicted ones, and confirm that proposed method is effective for reducing EMI, with measured near-field distribution. The proposed topology is suitable for design of high speed digital system.
EM Wave Absorbers with Au Coated Conductive Sheets
Song Jae-Man ; O Kyeung-Jin ; Kim Dong-Il ;
Journal of electromagnetic engineering and science, volume 6, issue 1, 2006, Pages 71~75
In this study, EM wave absorbers based on Au coated conductive sheets were prepared, and their reflection and transmission coefficients were investigated. An Au coated conductive sheet showed the transmission loss higher than 40 dB in
GHz. Ba ferrite EM wave absorbers with an Au coated conductive sheet showed enhanced EM wave absorption and shield to compare with Ba ferrite EM wave absorbers without conductive sheets. Proposed EM wave absorbers with conductive sheets are useful to protect EM machines from EM interference by strayfields.
The Interference Measurement Analysis between 3.412 GHz Band Broadcasting System and UWB Wireless Communication System
Song Hong-Jong ; Kim Dong-Ku ;
Journal of electromagnetic engineering and science, volume 6, issue 1, 2006, Pages 76~81
Ultra wideband(UWB) technologies have been developed to exploit a new spectrum resource in substances and to realize ultra-high-speed communication, high precision geo-location, and other applications. The energy of UWB signal is extremely spread from near DC to a few GHz. This means that the interference between conventional narrowband systems and UWB systems is inevitable. However, the interference effects had not previously been studied from UWB wireless systems to conventional wireless systems sharing the frequency bands such as Broadcasting system. This paper experimentally evaluates the interference from two kinds of UWB sources, namely a orthogonal frequency division Multiplex UWB source and an impulse radio UWB source, to a Broadcasting transmission system. The receive power degradations of broadcasting system are presented. From these experimental results, we show that in all practical cases UWB system can coexist 35 m distance in-band broadcasting network.