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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 12, Issue 4 - Dec 2012
Volume 12, Issue 3 - Sep 2012
Volume 12, Issue 2 - Jun 2012
Volume 12, Issue 1 - Mar 2012
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Optimal Throughput of Secondary Users over Two Primary Channels in Cooperative Cognitive Radio Networks
Vu, Ha Nguyen ; Kong, Hyung-Yun ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 1~7
DOI : 10.5515/JKIEES.2012.12.1.1
In this paper, we investigated the throughput of a cognitive radio network where two primary frequency channels (PCs) are sensed and opportunistically accessed by N secondary users. The sharing sensing member (SSM) protocol is introduced to sense both PCs simultaneously. According to the SSM protocol, N SUs (Secondary User) are divided into two groups, which allows for the simultaneous sensing of two PCs. With a frame structure, after determining whether the PCs are idle or active during a sensing slot, the SUs may use the remaining time to transmit their own data. The throughput of the network is formulated as a convex optimization problem. We then evaluated an iterative algorithm to allocate the optimal sensing time, fusion rule and the number of members in each group. The computer simulation and numerical results show that the proposed optimal allocation improves the throughput of the SU under a misdetection constraint to protect the PCs. If not, its initial date of receipt shall be nullified.
Decode-and-Forward Relaying Systems with N
Best-Relay Selection over Rayleigh Fading Channels
Duy, Tran Trung ; Kong, Hyung-Yun ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 8~12
DOI : 10.5515/JKIEES.2012.12.1.8
In this paper, we evaluate performances of dual-hop decode-and-forward relaying systems with the
best-relay selection scheme. In some schemes, such as scheduling or load balancing schemes, the best relay is unavailable and hence the system must resort the second best, third best, or generally the
best relay. We derive the expressions of the outage probability and symbol error rate (SER) for this scenario over Rayleigh fading channels. Monte-Carlo simulations are presented to verify the analytical results.
Cooperative Communication with Different Combining Techniques in One-Dimensional Random Networks
Duy, Tran Trung ; Kong, Hyung-Yun ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 13~19
DOI : 10.5515/JKIEES.2012.12.1.13
In this paper, we investigate cooperative transmission in one-dimensional random wireless networks. In this scheme, a stationary source communicates with a stationary destination with the help of N relays, which are randomly placed in a one-dimensional network. We derive exact and approximate expressions of the average outage probability over Rayleigh fading channels. Various Monte-Carlo simulations are presented to verify the accuracy of our analyses.
Design and Fabrication of the EM Wave Absorber with Excellent Characteristics for ETC System
Kim, Dong-Il ; Choi, Dong-Soo ; Choi, Dong-Han ; Kim, Do-Yeol ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 20~25
DOI : 10.5515/JKIEES.2012.12.1.20
In this paper, the EM wave absorber for ETC system was designed and fabricated. We fabricated several samples in different composition ratios of flaked sendust and CPE(Chlorinated Polyethylene). Absorption abilities were simulated in accordance with different thicknesses of the prepared absorbers and changed complex relative permittivity and permeability according to composition ratio. The optimized mixing ratio of flaked sendust and CPE was found as 60 : 40 wt.% by experiments and simulation. Then the EM wave absorber was fabricated and tested using the simulated data. As a result, the developed EM wave absorber has the thickness of 2.75 mm and absorption ability was 22.5 dB in the case of normal incidence at 5.8 GHz. Therefore, it was confirmed that the newly developed absorber can be used for ETC system.
A Sub-Wavelength Focusing Lens Composed of a Dual-Plate Metamaterial Providing a Negative Refractive Index
Kim, Dong-Ho ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 26~31
DOI : 10.5515/JKIEES.2012.12.1.26
We have proposed a metamaterial lens that enables sub-wavelength focusing, which is shorter than an operating wavelength. Our lens is a two dimensional array of a unit cell consisting of a metallic dual-plate printed on a dielectric substrate. The unique dual-plate structure provides negativeness both in permittivity and permeability, with no help from conventional additional structures, which are normally printed on the opposite of metallic patterns. Therefore, we can focus a source (or an image) in a tiny distance shorter than the free space wavelength (
) at the frequencies of interest. Furthermore, since the proposed geometry does not need separate supplementary structures to acquire negative permittivity or permeability, our lens is much simpler than conventional metamaterial lenses, which is a strong point in practical applications. We have validated sub-wavelength focusing ability in a 6 GHz frequency band through an experiment of near field scanning, which provided the width of about 0.19
at a half maximum of a peak value of an measured image. The width of the focused image through the lens is more than 4 times shorter than that without the lens, which confirms the validity of our design approach.
Spectrum Sensing in a Cognitive Body Area Network: Detection of a Bonded Channel in the MICS Band
Ahn, Chun-Su ; Choi, Jae-Hoon ; Kim, Sun-Woo ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 32~36
DOI : 10.5515/JKIEES.2012.12.1.32
In this paper, we present a novel algorithm for detecting a bonded channel in a cognitive radio network where channel bonding is allowed for a higher data rate. The envelope detection algorithm is proposed to distinguish the center frequency of the received signal in order to determine whether the signal is transmitted by a primary user occupying a single channel or a secondary user occupying more than two channels when the channel is in use.
Wireless RF Sensor Structure for Non-Contact Vital Sign Monitoring
Kim, Sang-Gyu ; Yun, Gi-Ho ; Yook, Jong-Gwan ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 37~44
DOI : 10.5515/JKIEES.2012.12.1.37
This paper describes a compact and novel wireless vital sign sensor at 2.4 GHz that can detect heartbeat and respiration signals. The oscillator circuit incorporates a planar resonator, which functions as a series feedback element as well as a near-field radiator. The periodic movement of a human body during aerobic exercise could cause an input impedance variation of the radiator within near-field range. This variation results in a corresponding change in the oscillation frequency and this change has been utilized for the sensing of human vital signs. In addition, a surface acoustic wave (SAW) filter and power detector have been used to increase the system sensitivity and to transform the frequency variation into a voltage waveform. The experimental results show that the proposed sensor placed 20 mm away from a human body can detect the vital signs very accurately.
A Uniform Asymptotic Solution for Transmitted Waves through a Plane Dielectric Interface from a Denser to a Rarer Mediums by Using Parabolic Cylinder Functions
Quang, Dinh Trong ; Goto, Keiji ; Kawano, Toru ; Ishihara, Toyohiko ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 45~54
DOI : 10.5515/JKIEES.2012.12.1.45
When the cylindrical wave is incident on a plane dielectric interface from a denser medium to a rarer one, the asymptotic solution for the transmitted wave in the near region is different from the one in the far region. In this paper, we have derived a novel uniform asymptotic solution represented by using the parabolic cylinder function for the transmitted and scattered waves observed in the rarer medium when the cylindrical wave is incident on the plane dielectric interface from the denser medium. The validity of the uniform asymptotic solution has been confirmed by comparing with the reference solution calculated numerically. It has been clarified that the transition wave plays an important role to connect smoothly the asymptotic solution in the near region to the one in the far region through the transition region. We have shown the very interesting phenomenon that the lateral wave type transmitted wave is observed in the far and shallow region.
ALIS : GPR System for Humanitarian Demining and Its Deployment in Cambodia
Sato, Motoyuki ; Yokota, Yuya ; Takahashi, Kazunori ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 55~62
DOI : 10.5515/JKIEES.2012.12.1.55
Humanitarian demining is very important issue not only in mine affected courtiers but also for the courtiers which are technically, politically and financially supporting the mine affected courtiers. In order to achieve higher efficiency of the mine clearance operation, new technologies can significantly contribute to the societies. Since 2002, Tohoku University, Japan has developed a sensor system "ALIS" for humanitarian demining. ALIS is a hand-held dual sensor, which combines an electromagnetic induction sensor (EMI) and a Ground Penetrating Radar (GPR). ALIS has a real-time sensor tracking system based on a CCD camera and which enables the image reconstruction. We have tested ALIS in Cambodia and found that it can eliminate more than 70 % metal fragments. Since 2009, 2 sets of ALIS have detected more than 80 anti-personnel mines, and cleared more than 137,000
The Design of Calculable Standard Dipole Antennas in the Frequency Range of 1~3 GHz
Kim, Ki-Chai ; Kim, Sang-Myeong ; Kwon, Jae-Yong ; Kang, Tae-Weon ; Kim, Jeong-Hwan ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 63~69
DOI : 10.5515/JKIEES.2012.12.1.63
This paper presents the design of a calculable standard dipole antenna with a hybrid balun in the frequency range of 1 GHz to 3 GHz. A new formula of the antenna factor for a dipole antenna with a hybrid balun is derived using the power mismatch-loss concept. The antenna factors derived in this paper are in good agreement with the results calculated from S-parameters. The design results show that the calculable dipole antenna with a hybrid balun can be characterized by power mismatch-loss component factors.
Comparison of Detection Probability for Conventional and Time-Reversal (TR) Radar Systems
Yoo, Hyung-Ha ; Koh, Il-Suek ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 70~76
DOI : 10.5515/JKIEES.2012.12.1.70
We compare the detection probabilities of the time-reversal(TR) detection system and the conventional radar system. The target is assumed to be hidden inside a random medium such as a forest. We propose a TR detection system based on the SAR(Synthetic Aperture Radar) algorithm. Unlike the conventional SAR images, the proposed TR-SAR system has an interesting property. Specifically, the target-related signal components due to the time-reversal refocusing characteristics, as well as some of clutter-related signal components are concentrated at the time-reversal reference point. The remaining clutter-related signal components are scattered around that reference point. In this paper, we model the random media as a collection of point scatterers to avoid unnecessary complexities. We calculate the detection probability of the TR radar system based on the proposed simple random media model.
Development of a MIMO-OTA System with Simplified Configuration
Karasawa., Yoshio ; Gunawan, Yannes ; Pasisingi, Sahrul ; Nakada, Katsuhiro ; Kosako, Akira ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 77~84
DOI : 10.5515/JKIEES.2012.12.1.77
This paper introduces our development of a MIMO-OTA system with simplified configuration. The key element of our proposal is the adoption of an antenna branch-controlled configuration for generating multipath delayed waves. The signal processing is carried out on IF band signal with an FPGA in a fading-emulator-type MIMO-OTA measurement system. The proposed scheme is largely different from available system configurations for the fading simulator method of constructing the OTA test environment. We describe the principle of the proposed scheme, channel model incorporated in the system, basic configuration of the developed system, and its performance.
A New Expression of Near-Field Gain Correction Using Photonic Sensor and Planar Near-Field Measurements
Hirose, Masanobu ; Kurokawa, Satoru ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 85~93
DOI : 10.5515/JKIEES.2012.12.1.85
We propose a new expression of the near-field gain correction to calculate the on-axis far-field gain from the onaxis near-field gain for a directive antenna. The new expression is represented by transversal vectorial transmitting characteristics of two antennas that are measured by planar near-field equipment. Due to the advantages of the photonic sensor, the utilization of the new expression realizes the measurements of the on-axis far-field gains for two kinds of double ridged waveguide horn antennas within 0.1 dB deviation from 1 GHz to 6 GHz without calibrating the photonic sensor system.
Analysis of Radio Interference through Ducting for 2.5 GHz WiMAX Service
Son, Ho-Kyung ; Kim, Jong-Ho ; Kim, Che-Young ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 94~100
DOI : 10.5515/JKIEES.2012.12.1.94
Radio interference has been occurring in mobile communication services on the southern seashore in Korea. Monitoring the radio interference signal revealed that the main reason for the radio interference was a radio ducting signal coming from the seaside of Japan. In this paper, we have analyzed the effect of interference on WiMAX service using a 2.5 GHz frequency band between Korea and Japan. We focus on the interference scenario from base station to base station and we use the Minimum Coupling Loss (MCL) method for interference analysis and the Advanced Propagation Model (APM) for calculating the propagation loss in ducts. The propagation model is also compared with experimental measurement data. We confirm that the interfering signal strength depends on the antenna height and this result can be applied to deployment planning for each system with an interference impact acceptable to both parties.
Monostatic RCS Reduction by Gap-Fill with Epoxy/MWCNT in Groove Pattern
Choi, Won-Ho ; Jang, Hong-Kyu ; Shin, Jae-Hwan ; Song, Tae-Hoon ; Kim, Jin-Kyu ; Kim, Chun-Gon ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 101~106
DOI : 10.5515/JKIEES.2012.12.1.101
In this study, we investigated the effect of groove pattern and gap-fill with lossy materials at 15 GHz frequency of Ku-band. We used Epoxy/MWCNT composite materials as gap-fill materials. Although epoxy does not have an absorbance capability, epoxy added conductive fillers, which are multi-walled carbon nanotubes (MWCNT), can function as radar absorbing material. Specimens were fabricated with different MWCNT mass fractions (0, 0.5, 1.0, 2.0 wt%) and their permittivity in the Ku-band was measured using the waveguide technique. We investigated the effect of gap-fill on monostatic RCS by calculating RCS with and without gap-fill. For arbitrarily chosen thickness and experimentally obtained relative permittivity, we chose the relative permittivity of MWCNT at 2 wt% (
=8.8-j2.4), which was the lowest reflection coefficient for given thickness of 3.3 mm at V-pol. and
incident angle. We also checked the monostatic RCS and the field intensity inside the groove channel. In the case of H-pol, gap-fill was not affected by the monostatic RCS and magnitude was similar with or without gap-fill. However, in the case of V-pol, gap-fill effectively reduced the monostatic RCS. The field intensity inside the groove channel reveals that different RCS behaviors depend on the wave polarizations.
3D Microwave Breast Imaging Based on Multistatic Radar Concept System
Simonov, Nikolai ; Jeon, Soon-Ik ; Son, Seong-Ho ; Lee, Jong-Moon ; Kim, Hyuk-Je ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 107~114
DOI : 10.5515/JKIEES.2012.12.1.107
Microwave imaging (MI) is one of the most promising and attractive new techniques for earlier breast cancer detection. Microwave tomography (MT) realizes configuration of a multistatic multiple-input multiple-output system and reconstructs dielectric properties of the breast by solving a nonlinear inversion scattering problem. In this paper, we describe ETRI 3D MT system with 3D MI reconstruction program and demonstrate its robustness through some examples of the image reconstruction.
Development of a Scattering Model for Soybean Fields and Verification with Scatterometer and SAR Data at X-Band
Kweon, Soon-Koo ; Hwang, Ji-Hwan ; Oh, Yi-Sok ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 115~121
DOI : 10.5515/JKIEES.2012.12.1.115
This paper presents a scattering model and measurements of backscattering coefficients for soybean fields. The polarimetric radar backscatters of a soybean field were measured using the ground-based X-band polarimetric scatterometer in an angular range from
. The backscattering coefficients were also obtained using the COSMO-SkyMed (Spotlight mode, HH-polarization) from July to October 2010. The backscattering coefficients of the soybean field were computed using the 1st-order radiative transfer model (RTM) with field-measured input parameters. The soybean layer is composed of the stems, branches, leaves, and soybean pods. The stems, branches, and pods are modeled with lossy dielectric cylinders, the leaves are modeled with lossy dielectric disks. The estimated backscattering coefficients agree quite well with the field-measured radar backscattering coefficients.
Extraction of S-Parameters for a Slot Unit on the Post-Wall Waveguide from Measured Data
Lee, Jae-Ho ; Park, Jung-Yong ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 122~127
DOI : 10.5515/JKIEES.2012.12.1.122
Post-wall waveguide structures have attracted a great deal of attention for micro- and millimeter-wave applications. One of the waveguide’s applications is a slotted waveguide array. In order to design the slotted array, the characteristics of a slot unit alone on the post-wall waveguide should be investigated. In this paper, a method for extracting the S-parameters of a unit slot is proposed. This simple method requires only two kinds of waveguides: waveguides without a slot unit and waveguides with a slot unit. Three kinds of slot units are fabricated, and the extracted results show a high level of agreement with predicted (simulated) results. With this method, the equivalent slot length can also be found.
A Topological Derivative Based Non-Iterative Electromagnetic Imaging of Perfectly Conducting Cracks
Ma, Yong-Ki ; Park, Won-Kwang ;
Journal of electromagnetic engineering and science, volume 12, issue 1, 2012, Pages 128~134
DOI : 10.5515/JKIEES.2012.12.1.128
In this manuscript, we consider electromagnetic imaging of perfectly conducting cracks completely hidden in a homogeneous material via boundary measurements. For this purpose, we carefully derive a topological derivative formula based on the asymptotic expansion formula for the existence of a perfectly conducting inclusion with a small radius. With this, we introduce a topological derivative based imaging algorithm and discuss its properties. Various numerical examples with noisy data show the effectiveness and limitations of the imaging algorithm.