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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal 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 16, Issue 3 - Jul 2016
Volume 16, Issue 2 - Apr 2016
Volume 16, Issue 1 - Jan 2016
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Synthesis of Bulk Medium with Negative Permeability Using Ring Resonators
Kim, Gunyoung ; Lee, Bomson ;
Journal of electromagnetic engineering and science, volume 16, issue 2, 2016, Pages 67~73
DOI : 10.5515/JKIEES.2016.16.2.67
This paper presents simple expressions for the effective permeability of bulk metamaterial consisting of ring resonators (RRs) or split ring resonators (SRRs) based on the convenient geometrical factors of the structure compared with wavelength. The resonant frequency dependence of the medium permeability, including loss effects, is analyzed in detail. Inverting the analysis equations, useful design (or synthesis) equations are derived for a systematic design process with some examples. This paper may particularly be useful for the design of a bulk metamaterial with a specific negative relative permeability at a desired frequency. The loss of metamaterials consisting of RRs (or SRRs) is also analyzed over a wide frequency band from 10 MHz to 10 THz.
Optimum Array Configuration to Improve Null Steering Time for Mobile CRPA Systems
Byun, Gangil ; Hyun, Jong-Chul ; Seo, Seung Mo ; Choo, Hosung ;
Journal of electromagnetic engineering and science, volume 16, issue 2, 2016, Pages 74~79
DOI : 10.5515/JKIEES.2016.16.2.74
This paper proposes an optimum array configuration to improve null steering time for mobile controlled reception pattern antenna (CRPA) systems. The proposed array consists of a single reference element at the center and nine auxiliary elements arranged in a circular array. The array radius and the vertical positions of the center element are optimized using a genetic algorithm in conjunction with a constrained least-mean-square algorithm. The results demonstrate that the proposed array is suitable for mobile CRPA systems without significant side nulls in satellite directions.
Proposal of an Algorithm for an Efficient Forward Link Adaptive Coding and Modulation System for Satellite Communication
Ryu, Joon-Gyu ; Oh, Deock-Gil ; Kim, Hyun-Ho ; Hong, Sung-Yong ;
Journal of electromagnetic engineering and science, volume 16, issue 2, 2016, Pages 80~86
DOI : 10.5515/JKIEES.2016.16.2.80
This paper proposes the algorithm for forward link adaptive coding and modulation (ACM) and the detailed design for a satellite communication system to improve network reliability and system throughput. In the ACM scheme, the coding and modulation schemes are changed by as much as the channel can provide depending on the quality of the communication link. To implement the forward link ACM system in the Ka-band, channel prediction and modulation/coding decision methods are proposed and simulated. The parameters of the adaptive filter predictor based on the least mean square are optimized, the minimum mean square error of the channel predictor is 0.0608 when step size and the number of filter tap are 0.0001 and 4, respectively. A test-bed is set up to verify the forward link ACM system, and a test is performed using a Ka-band satellite (i.e., Communication, Ocean, and Meteorological Satellite [COMS]). This test verifies that the ACM scheme can increase the system throughput.
Numerical Implementation of Representative Mobile Phone Models for Epidemiological Studies
Lee, Ae-Kyoung ; Yoon, Yonghyun ; Lee, Sooyung ; Lee, Byungje ; Hong, Seon-Eui ; Choi, Hyung-Do ; Cardis, Elisabeth ;
Journal of electromagnetic engineering and science, volume 16, issue 2, 2016, Pages 87~99
DOI : 10.5515/JKIEES.2016.16.2.87
This paper describes an implementation method and the results of numerical mobile phone models representing real phone models that have been released on the Korean market since 2002. The aim is to estimate the electromagnetic absorption in the human brain for case-control studies to investigate health risks related to mobile phone use. Specific absorption rate (SAR) compliance test reports about commercial phone models were collected and classified in terms of elements such as the external body shape, the antenna, and the frequency band. The design criteria of a numerical phone model representing each type of phone group are as follows. The outer dimensions of the phone body are equal to the average dimensions of all commercial models with the same shape. The distance and direction of the maximum SAR from the earpiece and the area above -3 dB of the maximum SAR are fitted to achieve the average obtained by measuring the SAR distributions of the corresponding commercial models in a flat phantom. Spatial peak 1-g SAR values in the cheek and tilt positions against the specific anthropomorphic mannequin phantom agree with average data on all of the same type of commercial models. Second criterion was applied to only a few types of models because not many commercial models were available. The results show that, with the exception of one model, the implemented numerical phone models meet criteria within 30%.
Three-Channel Output Multiplexer Design Using Band-Pass Filter and Ultra-Wideband Antenna
Lee, Jung Nam ; Park, Jong Kweon ;
Journal of electromagnetic engineering and science, volume 16, issue 2, 2016, Pages 100~105
DOI : 10.5515/JKIEES.2016.16.2.100
We have designed a three-channel output multiplexer (OMUX) using a band-pass filter and an ultra-wideband (UWB) antenna. The proposed band-pass filter is composed of an inner rectangular loop, an outer open stub, and a defected ground structure. The outer open stub can be used to control the pass band, and the inner rectangular loop can improve the insertion loss characteristics of the band-pass filter. The proposed band-pass filter, UWB antenna, and OMUX are fabricated and measured. The designed OMUX can cover the band group 1 (3,168-4,752 MHz) of WiX system. The measured radiation patterns are close to those of a conventional dipole antenna and the measured antenna gain varies from 1.8 dBi to 3 dBi over the operating frequency range.
Design of Thin RC Absorbers Using a Silver Nanowire Resistive Screen
Lee, Junho ; Lee, Bomson ;
Journal of electromagnetic engineering and science, volume 16, issue 2, 2016, Pages 106~111
DOI : 10.5515/JKIEES.2016.16.2.106
A resistive and capacitive (RC) microwave absorber with a layer thickness less than a quarter of a wavelength is investigated based on closed-form design equations, which are derived from the equivalent circuit of the RC absorber. The RC absorber is shown to have a theoretical 90% absorption bandwidth of 93% when the electrical layer thickness is
). The trade-offs between the layer thickness and the absorption bandwidth are also elucidated. The presented formulation is validated by a design example at 3 GHz. The RC absorber is realized using a silver nanowire resistive rectangular structure with surrounding gaps. The measured 90% absorption bandwidth with a layer thickness of
is 76% from 2.3 GHz to 5.1 GHz in accordance with the theory and EM simulations. The presented design methodology is scalable to other frequencies.
Alternative Expressions for Mutual Inductance and Coupling Coefficient Applied in Wireless Power Transfer
Kim, Gunyoung ; Lee, Bomson ;
Journal of electromagnetic engineering and science, volume 16, issue 2, 2016, Pages 112~118
DOI : 10.5515/JKIEES.2016.16.2.112
Alternative analytic expressions for the mutual inductance (
) and coupling coefficient (k) between circular loops are presented using more familiar and convenient expressions that represent the property of reciprocity clearly. In particular, the coupling coefficients are expressed in terms of structural dimensions normalized to a geometric mean of radii of two loops. Based on the presented expressions, various aspects of the mutual inductances and coupling coefficients, including the regions of positive, zero, and negative value, are examined with respect to their impacts on the efficiency of wireless power transmission.
Identifying the Appropriate Position on the Ground Plane for MIMO Antennas Using Characteristic Mode Analysis
Won, Jusun ; Jeon, Sinhyung ; Nam, Sangwook ;
Journal of electromagnetic engineering and science, volume 16, issue 2, 2016, Pages 119~125
DOI : 10.5515/JKIEES.2016.16.2.119
In this paper, a method for identifying the appropriate position on the ground plane for antennas is proposed based on the current correlation coefficient (
). This method explains that the mutual coupling between antennas when locating several antennas on the same ground plane is necessary. Given the current distribution on the ground plane induced by each antenna, easily estimating the coupling between antennas is possible. This paper also demonstrates that the proposed method can be used in the design of a multi-input multi-output system. The measured data are in good agreement with the simulation results.
Analysis of Efficiencies for Multiple-Input Multiple-Output Wireless Power Transfer Systems
Kim, Sejin ; Lee, Bomson ;
Journal of electromagnetic engineering and science, volume 16, issue 2, 2016, Pages 126~133
DOI : 10.5515/JKIEES.2016.16.2.126
Wireless power transfer (WPT) efficiencies for multiple-input multiple-output (MIMO) systems are formulated with a goal of achieving their maximums using Z matrices. The maximum efficiencies for any arbitrarily given configurations are obtained using optimum loads, which can be determined numerically through adequate optimization procedures in general. For some simpler special cases (single-input single-output, single-input multiple-output, and multiple-input single-output) of the MIMO systems, the efficiencies and optimum loads to maximize them can be obtained using closed-form expressions. These closed-form solutions give us more physical insight into the given WPT problem. These efficiencies are evaluated theoretically based on the presented formulation and also verified with comparisons with circuit- and EM-simulation results. They are shown to lead to a good agreement. This work may be useful for construction of the wireless Internet of Things, especially employed with energy autonomy.
Creating a Gain Enhancement Technique for a Conical Horn Antenna by Adding a Wire Medium Structure at the Aperture
Duangtang, Pumipong ; Mesawad, Piyaporn ; Wongsan, Rangsan ;
Journal of electromagnetic engineering and science, volume 16, issue 2, 2016, Pages 134~142
DOI : 10.5515/JKIEES.2016.16.2.134
This paper proposes a technique for improving the conventional conical horn antenna for the X-band frequency using metamaterial on a wire medium structure. The main idea of this research is the application of the wire medium metamaterial to the conical horn's aperture for the enhancement of the horn's gain; this is done without changing the antenna's dimensions. The results show that the wire medium structure can increase the gain of a conventional conical horn antenna from approximately 17.7 dB to 20.9 dB (an increase of approximately 3.2 dB). A prototype antenna was fabricated, and its fundamental parameters including its reflection coefficient (
), radiation patterns, and directive gain were measured. The simulated and measured results were very good. The wire medium structure of the proposed antenna improved the radiation pattern, enhanced the directivity, increased the gain, and reduced the side lobe level using a simple integrated wire medium structure.