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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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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 16, Issue 3 - Jul 2016
Volume 16, Issue 2 - Apr 2016
Volume 16, Issue 1 - Jan 2016
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Design of a Highly Efficient Broadband Class-E Power Amplifier with a Low Q Series Resonance
Ninh, Dang-Duy ; Nam, Ha-Van ; Kim, Hyoungjun ; Seo, Chulhun ;
Journal of electromagnetic engineering and science, volume 16, issue 3, 2016, Pages 143~149
DOI : 10.5515/JKIEES.2016.16.3.143
This work presents a method used for designing a broadband class-E power amplifier that combines the two techniques of a nonlinear shunt capacitance and a low quality factor of a series resonator. The nonlinear shunt capacitance theory accurately extracts the value of class-E components. In addition, the quality factor of the series resonator was considered to obtain a wide bandwidth for the power amplifiers. The purpose of using this method was to produce a simple topology and a high efficiency, which are two outstanding features of a class-E power amplifier. The experimental results show that a design was created using from a 130 to 180 MHz frequency with a bandwidth of 32% and a peak measured power added efficiency of 84.8%. This prototype uses an MRF282SR1 MOSFET transistor at a 3-W output power level. Furthermore, a summary of the experimental results compared with other high-efficiency articles is provided to validate the advantages of this method.
Effects of Sheet Thickness on the Electromagnetic Wave Absorbing Characterization of Li
-Ferrite Composite as a Radiation Absorbent Material
Kim, Dong-Young ; Yoon, Young-Ho ; Jo, Kwan-Jun ; Jung, Gil-Bong ; An, Chong-Chul ;
Journal of electromagnetic engineering and science, volume 16, issue 3, 2016, Pages 150~158
DOI : 10.5515/JKIEES.2016.16.3.150
This paper reports on a study of LiNiZn-ferrite composite as a radiation absorbent material (RAM). The electromagnetic (EM) wave absorbers are composed of an EM wave absorbing material and a polymeric binder. The surface morphology, chemical composition, weight percent of the ferrite composite of the toroid sample, magnetic properties, and return loss are investigated using field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), and network analyzer. For preparing the absorbing sheet, chlorinated polyethylene (CPE) is used as a polymeric binder. The EM wave absorption properties of the prepared samples were studied at 4 - 8 GHz. We can confirm the effects of the thickness of the samples for absorption properties. An absorption bandwidth of more than a 10-dB return loss shifts toward a lower frequency range along with an increase in the thickness of the absorber.
A Frequency Tunable Double Band-Stop Resonator with Voltage Control by Varactor Diodes
Wang, Yang ; Yoon, Ki-Cheol ; Lee, Jong-Chul ;
Journal of electromagnetic engineering and science, volume 16, issue 3, 2016, Pages 159~163
DOI : 10.5515/JKIEES.2016.16.3.159
In this paper, a frequency tunable double band-stop resonator (BSR) with voltage control by varactor diodes is suggested. It makes use of a half-wavelength shunt stub as its conventional basic structure, which is replaced by the distributed LC block. Taking advantage of the nonlinear relationship between the frequency and electrical length of the distributed LC block, a dual-band device can be designed easily. With two varactor diodes, the stop-band of the resonator can be easily tuned by controlling the electrical length of the resonator structure. The measurement results show the tuning ranges of the two operating frequencies to be 1.82 GHz to 2.03 GHz and 2.81 GHz to 3.03 GHz, respectively. The entire size of the resonator is
, which is very compact.
A Dual-Band Through-the-Wall Imaging Radar Receiver Using a Reconfigurable High-Pass Filter
Kim, Duksoo ; Kim, Byungjoon ; Nam, Sangwook ;
Journal of electromagnetic engineering and science, volume 16, issue 3, 2016, Pages 164~168
DOI : 10.5515/JKIEES.2016.16.3.164
A dual-band through-the-wall imaging radar receiver for a frequency-modulated continuous-wave radar system was designed and fabricated. The operating frequency bands of the receiver are S-band (2-4 GHz) and X-band (8-12 GHz). If the target is behind a wall, wall-reflected waves are rejected by a reconfigurable
high-pass filter. The filter is designed using a high-order admittance synthesis method, and consists of transconductor circuits and capacitors. The cutoff frequency of the filter can be tuned by changing the reference current. The receiver system is fabricated on a printed circuit board using commercial devices. Measurements show 44.3 dB gain and 3.7 dB noise figure for the S-band input, and 58 dB gain and 3.02 dB noise figure for the X-band input. The cutoff frequency of the filter can be tuned from 0.7 MHz to 2.4 MHz.
Design, Analysis, and Equivalent Circuit Modeling of Dual Band PIFA Using a Stub for Performance Enhancement
Yousaf, Jawad ; Jung, Hojin ; Kim, Kwangho ; Nah, Wansoo ;
Journal of electromagnetic engineering and science, volume 16, issue 3, 2016, Pages 169~181
DOI : 10.5515/JKIEES.2016.16.3.169
This work presents a new method for enhancing the performance of a dual band Planer Inverted-F Antenna (PIFA) and its lumped equivalent circuit formulation. The performance of a PIFA in terms of return loss, bandwidth, gain, and efficiency is improved with the addition of the proposed open stub in the radiating element of the PIFA without disturbing the operating resonance frequencies of the antenna. In specific cases, various simulated and fabricated PIFA models illustrate that the return loss, bandwidth, gain, and efficiency values of antennas with longer optimum open stub lengths can be enhanced up to 4.6 dB, 17%, 1.8 dBi, and 12.4% respectively, when compared with models that do not have open stubs. The proposed open stub is small and does not interfere with the surrounding active modules; therefore, this method is extremely attractive from a practical implementation point of view. The second presented work is a simple procedure for the development of a lumped equivalent circuit model of a dual band PIFA using the rational approximation of its frequency domain response. In this method, the PIFA's measured frequency response is approximated to a rational function using a vector fitting technique and then electrical circuit parameters are extracted from it. The measured results show good agreement with the electrical circuit results. A correlation study between circuit elements and physical open stub lengths in various antenna models is also discussed in detail; this information could be useful for the enhancement of the performance of a PIFA as well as for its systematic design. The computed radiated power obtained using the electrical model is in agreement with the radiated power results obtained through the full wave electromagnetic simulations of the antenna models. The presented approach offers the advantage of saving computation time for full wave EM simulations. In addition, the electrical circuit depicting almost perfect characteristics for return loss and radiated power can be shared with antenna users without sharing the actual antenna structure in cases involving confidentiality limitations.
Modelling and Simulation Resolution of Ground-Penetrating Radar Antennas
Alsharahi, G. ; Mostapha, A. Mint Mohamed ; Faize, A. ; Driouach, A. ;
Journal of electromagnetic engineering and science, volume 16, issue 3, 2016, Pages 182~190
DOI : 10.5515/JKIEES.2016.16.3.182
The problem of resolution in antenna ground-penetrating radar (GPR) is very important for the investigation and detection of buried targets. We should solve this problem with software or a numeric method. The purposes of this paper are the modelling and simulation resolution of antenna radar GPR using three antennas, arrays (as in the software REFLEXW), the antenna dipole (as in GprMax2D), and a bow-tie antenna (as in the experimental results). The numeric code has been developed for study resolution antennas by scattered electric fields in mode B-scan. Three frequency antennas (500, 800, and 1,000 MHz) have been used in this work. The simulation results were compared with experimental results obtained by Rial and colleagues under the same conditions.
Study on Improving the Phase Noise of Broadband Voltage-Controlled Oscillator
Go, Min-Ho ; Kim, Hyoung-Joo ;
Journal of electromagnetic engineering and science, volume 16, issue 3, 2016, Pages 191~193
DOI : 10.5515/JKIEES.2016.16.3.191
This paper proposes a voltage-controlled oscillator (VCO) that has broadband turning and low-level of phase noise characteristics. Due to the micro-strip line resonant circuit with a low Q value, which is applied to the broadband tuning range, the depreciated phase noise performance is compensated by restraining the harmonics of the oscillating frequency. The VCO was designed according to the proposed structure as well as the conventional structure, and the superiority of the proposed structure was verified through its simulation, fabrication, and measurement.
An Eight-Element Compact Low-Profile Planar MIMO Antenna Using LC Resonance with High Isolation
Kwon, DukSoo ; Lee, Soo-Ji ; Kim, Jin-Woo ; Ahn, ByungKuon ; Yu, Jong-Won ; Lee, Wang-Sang ;
Journal of electromagnetic engineering and science, volume 16, issue 3, 2016, Pages 194~197
DOI : 10.5515/JKIEES.2016.16.3.194
An eight-element compact low-profile multi-input multi-output (MIMO) antenna is proposed for wireless local area network (WLAN) mobile applications. The proposed antenna consists of eight inverted-F antennas with an isolation-enhanced structure. By inserting the isolation-enhanced structure between the antenna elements, the slot and capacitor pair generates additional resonant frequency and decreases mutual coupling between the antenna elements. The overall size of the proposed antenna is only
, which is integrated into an area of just
. The proposed antenna meets 5-GHz WLAN standards with an operation bandwidth of 4.86 - 5.27 GHz and achieves an isolation of approximately 30 dB at 5 GHz. The simulated and measured results for the proposed antenna are presented and compared.