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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
Editor in Chief :
Volume & Issues
Volume 16, Issue 3 - Jul 2016
Volume 16, Issue 2 - Apr 2016
Volume 16, Issue 1 - Jan 2016
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Analysis of Microwave-Induced Thermoacoustic Signal Generation Using Computer Simulation
Dewantari, Aulia ; Jeon, Se-Yeon ; Kim, Seok ; Nikitin, Konstantin ; Ka, Min-Ho ;
Journal of electromagnetic engineering and science, volume 16, issue 1, 2016, Pages 1~6
DOI : 10.5515/JKIEES.2016.16.1.1
Computer simulations were conducted to demonstrate the generation of microwave-induced thermoacoustic signal. The simulations began with modelling an object with a biological tissue characteristic and irradiating it with a microwave pulse. The time-varying heating function data at every particular point on the illuminated object were obtained from absorbed electric field data from the simulation result. The thermoacoustic signal received at a point transducer at a particular distance from the object was generated by applying heating function data to the thermoacoustic equation. These simulations can be used as a foundation for understanding how thermoacoustic signal is generated and can be applied as a basis for thermoacoustic imaging simulations and experiments in future research.
Microwave Negative Group Delay Circuit: Filter Synthesis Approach
Park, Junsik ; Chaudhary, Girdhari ; Jeong, Junhyung ; Jeong, Yongchae ;
Journal of electromagnetic engineering and science, volume 16, issue 1, 2016, Pages 7~12
DOI : 10.5515/JKIEES.2016.16.1.7
This paper presents the design of a negative group delay circuit (NGDC) using the filter synthesis approach. The proposed design method is based on a frequency transformation from a low-pass filter (LPF) to a bandstop filter (BSF). The predefined negative group delay (NGD) can be obtained by inserting resistors into resonators. To implement a circuit with a distributed transmission line, a circuit conversion technique is employed. Both theoretical and experimental results are provided for validating of the proposed approach. For NGD bandwidth and magnitude flatness enhancements, two second-order NGDCs with slightly different center frequencies are cascaded. In the experiment, group delay of
and insertion loss of
are obtained in the frequency range of 1.935-2.001 GHz.
High Selectivity Coupled Line Impedance Transformer with Second Harmonic Suppression
Kim, Phirun ; Park, Junsik ; Jeong, Junhyung ; Jeong, Seungho ; Chaudhary, Girdhari ; Jeong, Yongchae ;
Journal of electromagnetic engineering and science, volume 16, issue 1, 2016, Pages 13~18
DOI : 10.5515/JKIEES.2016.16.1.13
This paper presents a design of an impedance transformer (IT) with high frequency selectivity characteristics. The frequency selectivity can be controlled by even- and odd-mode impedance of a shunt coupled transmission line (TL). For experimental validation, a 50- to
IT was implemented at a center frequency (
) of 2.6 GHz for the long-term evolution signal. The measured results were in good agreement with the simulations, showing a return loss higher than 19 dB over a passband bandwidth of 0.63 GHz (2.28-2.91 GHz) and good sharp frequency selectivity characteristic near to the passband. The series coupled TL provides a transmission zero at 5.75 GHz, whereas the shunt coupled TL provides three transmission zeros located at 2 GHz, 3.1 GHz, and 7.14 GHz.
Design of Dual-Band Bandpass Filters for Cognitive Radio Application of TVWS Band
Kwon, Kun-An ; Kim, Hyun-Keun ; Yun, Sang-Won ;
Journal of electromagnetic engineering and science, volume 16, issue 1, 2016, Pages 19~23
DOI : 10.5515/JKIEES.2016.16.1.19
This paper presents a novel design for dual-band bandpass filters. The proposed filters are applicable to the carrier aggregation of the TV white space (TVWS) band and long-term evolution (LTE) band for cognitive radio applications. The lower passband is the TVWS band (470-698 MHz) whose fractional bandwidth is 40 %, while the higher passband is the LTE band (824-894 MHz) with 8 % fractional bandwidth. Since the two passbands are located very close to each other, a transmission zero is inserted to enhance the rejection level between the two passbands. The TVWS band filter is designed using magnetic coupling to obtain a wide bandwidth, and the LTE band filter is designed using dielectric resonators to achieve good insertion loss characteristics. In addition, in the proposed design, a transmission zero is placed with cross-coupling. The proposed dual-band bandpass filter is designed as a two-port filter (one input/one output) as well as a three-port filter (one common input/two outputs). The measured performances show good agreement with the simulated performances.
RF Conductivity Measurement of Conductive Zell Fabric
Nguyen, Tien Manh ; Chung, Jae-Young ;
Journal of electromagnetic engineering and science, volume 16, issue 1, 2016, Pages 24~28
DOI : 10.5515/JKIEES.2016.16.1.24
This study presents a conductivity measurement technique that is applicable at radio frequencies (RF). Of particular interest is the measurement of the RF conductivity of a flexible Zell fabric, which is often used to implement wearable antennas on clothes. First, the transmission coefficient is measured using a planar microstrip ring resonator, where the ring is made of a Zell fabric. Then, the fabric's conductivity is determined by comparing the measured transmission coefficient to a set of simulation data. Specifically, a MATLAB-based root-searching algorithm is used to find the minimum of an error function composed of measured and simulation data. Several error functions have been tested, and the results showed that an error function employing only the magnitude of the transmission coefficient was the best for determining the conductivity. The effectiveness of this technique is verified by the measurement of a known copper foil before characterizing the Zell fabric. The conductivity of the Zell fabric at 2 GHz appears to be within the order of
, which is lower than the DC conductivity of
Design of a Switchplexer Based on a Microstrip Ring Resonator with Single-Switch Operation
Park, Wook-Ki ; Ahn, Chi-Hyung ; Kim, In-Ryeol ; Oh, Soon-Soo ;
Journal of electromagnetic engineering and science, volume 16, issue 1, 2016, Pages 29~34
DOI : 10.5515/JKIEES.2016.16.1.29
This paper proposes a reconfigurable microstrip diplexer, also known as a switchplexer, for use with single-switch operation of frequency band and output path. The proposed switchplexer is composed of a rectangular ring resonator and a switch on a shorting pin, which is inserted between the ring resonator and the ground plane. The rotated main current distributions occurring at different switch statuses provide the diplexer's different operating bands and different output ports. The performance of the simply designed switchplexer is successfully demonstrated via simulation and measurement.
Quadruple Band-Notched Trapezoid UWB Antenna with Reduced Gains in Notch Bands
Jin, Yunnan ; Tak, Jinpil ; Choi, Jaehoon ;
Journal of electromagnetic engineering and science, volume 16, issue 1, 2016, Pages 35~43
DOI : 10.5515/JKIEES.2016.16.1.35
A compact ultra-wide band antenna with a quadruple band-notched characteristic is proposed. The proposed antenna consists of a slotted trapezoid patch radiator, an inverted U-shaped band stop filter, a pair of C-shaped band stop filters, and a rectangular ground plane. To realize the quadruple notch-band characteristic, a U-shaped slot, a complementary split ring resonator, an inverted U-shaped band stop filter, and two C-shaped band stop filters are utilized in this antenna. The antenna satisfies the -10 dB reflection coefficient bandwidth requirement in the frequency band of 2.88-12.67 GHz, with a band-rejection characteristic in the WiMAX (3.43-3.85 GHz), WLAN (5.26-6.01 GHz), X-band satellite communication (7.05-7.68 GHz), and ITU 8 GHz (8.08-8.87 GHz) signal bands. In addition, the proposed antenna has a compact volume of
while maintaining omnidirectional patterns in the H-plane. The experimental and simulated results of the proposed antenna are shown to be in good agreement.
6-18 GHz Reactive Matched GaN MMIC Power Amplifiers with Distributed L-C Load Matching
Kim, Jihoon ; Choi, Kwangseok ; Lee, Sangho ; Park, Hongjong ; Kwon, Youngwoo ;
Journal of electromagnetic engineering and science, volume 16, issue 1, 2016, Pages 44~51
DOI : 10.5515/JKIEES.2016.16.1.44
GaN process is used to implement 6-18 GHz wideband power amplifier (PA) monolithic microwave integrated circuits (MMICs). GaN HEMTs are advantageous for enhancing RF power due to high breakdown voltages. However, the large-signal models provided by the foundry service cannot guarantee model accuracy up to frequencies close to their maximum oscillation frequency (
). Generally, the optimum output load point of a PA varies severely according to frequency, which creates difficulties in generating watt-level output power through the octave bandwidth. This study overcomes these issues by the development of in-house large-signal models that include a thermal model and by applying distributed L-C output load matching to reactive matched amplifiers. The proposed GaN PAs have successfully accomplished output power over 5 W through the octave bandwidth.
Split Slant-End Stubs for the Design of Broadband Efficient Power Amplifiers
Park, Youngcheol ; Kang, Taeggu ;
Journal of electromagnetic engineering and science, volume 16, issue 1, 2016, Pages 52~56
DOI : 10.5515/JKIEES.2016.16.1.52
This paper suggests a class-F power amplifier with split open-end stubs to provide a broadband high-efficiency operation. These stubs are designed to have wide bandwidth by splitting wide open-end stubs into narrower stubs connected in shunt in an output matching network for class-F operation. In contrast to conventional wideband class-F designs, which theoretically need a large number of matching lines, this method requires fewer transmission lines, resulting in a compact circuit implementation. In addition, the open-end stubs are designed with slant ends to achieve additional wide bandwidth. To verify the suggested design, a 10-W class-F power amplifier operating at 1.7 GHz was implemented using a commercial GaN transistor. The measurement results showed a peak drain efficiency of 82.1% and 750 MHz of bandwidth for an efficiency higher than 63%. Additionally, the maximum output power was 14.45 W at 1.7 GHz.
Mode Analysis of Cascaded Four-Conductor Lines Using Extended Mixed-Mode S-Parameters
Zhang, Nan ; Nah, Wansoo ;
Journal of electromagnetic engineering and science, volume 16, issue 1, 2016, Pages 57~65
DOI : 10.5515/JKIEES.2016.16.1.57
In this paper, based on the mode analysis of four-conductor lines, the extended mixed-mode chain-parameters and S-parameters of four-conductor lines are estimated using current division factors. The extended mixed-mode chain-parameters of cascaded four-conductor lines are then obtained with mode conversion. And, the extended mixed-mode S-parameters of cascaded four-conductor lines can be predicted from the transformation of the extended chain-parameters. Compared to the extended mixed-mode S-parameters of four-conductor lines, the cross-mode S-parameters are induced in the extended mixed-mode S-parameters of cascaded four-conductor lines, due to the imbalanced current division factors of cascaded two sections. The generated cross-mode S-parameters make the equivalent different- and common-mode conductors not independent from each other again. In addition, a new mode conversion, which applies the imbalanced current division factors, between the extended mixed-mode S-parameters and standard S-parameters is also proposed in this paper. Finally, the validity of the proposed extended mixed-mode S-parameters and mode conversion is confirmed by a comparison of the simulated and estimated results of shielded cable.