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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 14, Issue 4 - Dec 2014
Volume 14, Issue 3 - Sep 2014
Volume 14, Issue 2 - Jun 2014
Volume 14, Issue 1 - Mar 2014
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Modern Software Defined Radar (SDR) Technology and Its Trends
Kwag, Young-Kil ; Jung, Jung-Soo ; Woo, In-Sang ; Park, Myeong-Seok ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 321~328
DOI : 10.5515/JKIEES.2014.14.4.321
Software defined radar (SDR) is a multi-purpose radar system where most of the hardware processing is performed by software. This paper introduces a concept and technology trends of software defined radar, and addresses the advantages and limitations of the current SDR radar systems. For the advanced SDR concept, the KAU SDR Model (KSM) is presented for the multimode and multiband radar system operating in S-, X-, and K-bands. This SDR consists of a replaceable multiband antenna and RF hardware, common digital processor module with multimode, and open software platform based on MATLAB and LabVIEW. The new concept of the SDR radar can be useful in various applications of the education, traffic monitoring and safety, security, and surveillance depending on the various radar environments.
Realization of Alignment-Free WPT System
Park, Byung-Chul ; Son, Yong-Ho ; Jang, Byung-Jun ; Lee, Jeong-Hae ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 329~331
DOI : 10.5515/JKIEES.2014.14.4.329
A simple realization of an alignment-free wireless power transmission (WPT) system is presented in this letter. The WPT system consists of a transmitter with three reconfigurable modes corresponding to various controllable magnetic field directions in the azimuthal plane and an algorithm for the optimum mode selection carried by sensing the reflected voltage of the system. Twelve light emitting diodes (LEDs) are used to confirm the on- and off-state of LEDs powered wirelessly by the transmitter at every
of the azimuthal plane. A criterion voltage from the reflected power of the system is found by using the correlation between the reflected voltage and the on- and off-state of the LEDs. Simply by continuous; monitoring of the voltage from the system, the system maintains power to the LEDs. The system is realized by MATLAB/Simulink and a National Instrument data acquisition device (DAQ) board. Measurements using the system show on-state LEDs in the azimuthal plane except at the angles of
Investigation of Phase Singularity Problem in Microwave Breast Tomography
Son, Seong-Ho ; Simonov, Nikolai ; Lee, Kwang-Jae ; Jeon, Soon-Ik ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 332~335
DOI : 10.5515/JKIEES.2014.14.4.332
This paper investigates the phase singularity problem in microwave image reconstruction utilizing unwrapped phase data. The measured phases of the electric fields in most microwave measurement systems are wrapped. Thus, a certain phase unwrapping process is necessary for reconstruction of the image of a high contrast object. This unwrapping, however, is difficult in the presence of scattering nulls on/near the unwrapping path. At the null point, the phase value will be rendered, resulting in a poor image reconstruction. In this paper, we investigate the phase singularity arising from electromagnetic scattering nulls in microwave breast tomographic imaging. We then propose a transformation technique for the measured electric fields that avoids phase singularity.
Measurement Data Comparison of Fast SAR Measurement System by Probe Arrays with Robot Scanning SAR Measurement System
Kim, Jun Hee ; Gimm, Yoon-Myoung ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 336~341
DOI : 10.5515/JKIEES.2014.14.4.336
Dosimetry of radiating electromagnetic wave from mobile devices to human body has been evaluated by measuring Specific Absorption Rate (SAR). Usual SAR measurement system scans the volume by robot arm to evaluate RF power absorption to human body from wireless devices. It is possible to fast estimate the volume SAR by software deleting robot moving time with the 2D surface SAR data acquired by arrayed probes. This paper shows the principle of fast SAR measurement and the measured data comparison between the fast SAR system and the robot scanning system. Data of the fast SAR is well corresponding with data of robot scanning SAR within
dB, and its dynamic range covers from 10 mW/kg to 30 W/kg with 4.8 mm probe diameter.
High Output Power and High Fundamental Leakage Suppression Frequency Doubler MMIC for E-Band Transceiver
Chang, Dong-Pil ; Yom, In-Bok ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 342~345
DOI : 10.5515/JKIEES.2014.14.4.342
An active frequency doubler monolithic microwave integrated circuit (MMIC) for E-band transceiver applications is presented in this letter. This MMIC has been fabricated in a commercial
GaAs pseudomorphic high electron mobility transistor (pHEMT) process on a 2-mil thick substrate wafer. The fabricated MMIC chip has been measured to have a high output power performance of over 13 dBm with a high fundamental leakage suppression of more than 38 dBc in the frequency range of 71 to 86 GHz under an input signal condition of 10 dBm. A microstrip coupled line is used at the output circuit of the doubler section to implement impedance matching and simultaneously enhance the fundamental leakage suppression. The fabricated chip is has a size of
Optimization of a Defected Ground Structure to Improve Electromagnetic Bandgap Performance
Kwon, Manseok ; Kim, Myunghoi ; Kam, Dong Gun ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 346~348
DOI : 10.5515/JKIEES.2014.14.4.346
A dispersion analysis is performed to estimate the stopband characteristics of electromagnetic bandgap (EBG) structures with defected ground structures (DGS) of various shapes. Design guidelines are suggested for both elliptical and rectangular DGS patterns that result in a maximum stopband bandwidth for a given perforation area. This method provides a basis for numerical optimization techniques that can be used in synthesizing DGS shapes to meet bandgap requirements and layout constraints.
Achievable Ergodic Capacity of a MIMO System with a MMSE Receiver
Kim, Jae Hong ; Kim, Nam Shik ; Song, Bong Seop ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 349~352
DOI : 10.5515/JKIEES.2014.14.4.349
This paper considers the multiple-input multiple-output (MIMO) system with linear minimum mean square error (MMSE) detection under ideal fast fading. For
receive antennas, we derive the achievable ergodic capacity of MMSE detection exactly. When MMSE detection is considered in a receiver, we introduce a different approach that gives the approximation of a MIMO channel capacity at high signal-to-noise ratio (SNR). The difference between the channel capacity and the achievable capacity of MMSE detection converges to some constant that depends only on the number of antennas. We validate the analytical results by comparing them with Monte Carlo simulated results.
Interference Effects of Low-Power Devices on the UE Throughput of a CR-Based LTE System
Kim, Soyeon ; Sung, Wonjin ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 353~359
DOI : 10.5515/JKIEES.2014.14.4.353
Recently, the use of mobile devices has increased, and mobile traffic is growing rapidly. In order to deal with such massive traffic, cognitive radio (CR) is applied to efficiently use limited-spectrum resources. However, there can be multiple communication systems trying to access the white space (unused spectrum), and inevitable interference may occur to cause mutual performance degradation. Therefore, understanding the effects of interference in CR-based systems is crucial to meaningful operations of these systems. In this paper, we consider a long-term evolution (LTE) system using additional spectra by accessing the TV white space, where low-power devices (LPDs) are licensed primary users, in addition to TV broadcasting service providers. We model such a heterogeneous system to analyze the co-existence problem and evaluate the interference effects of LPDs on LTE user equipment (UE) throughput. We then present methods to mitigate the interference effects of LPDs by 'de-selecting' some of the UEs to effectively increase the overall sector throughput of the CR-based LTE system.
Single-Feed Composite Cavity-Backed Four-Arm Curl Antenna
Ta, Son Xuat ; Park, Ikmo ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 360~366
DOI : 10.5515/JKIEES.2014.14.4.360
A single-feed composite cavity-backed four-arm curl antenna is presented for use in global positioning systems (GPS). Its primary radiating element is fed by a vacant-quarter printed ring, which helps the antenna directly match to a
coaxial line and produce a good circular polarization (CP). The cavity-backed reflector is employed to improve the CP radiation characteristics in terms of 3-dB axial ratio (AR) beamwidth and minimum AR value. The optimized design with an overall size of
at 1,575 MHz) results in a
bandwidth of 8.66% (1,514-1,651 MHz) and a 3-dB AR bandwidth of 2.23% (1,555-1,590 MHz). The antenna radiates a widebeam right-hand circular polarization and operates with a measured radiation efficiency greater than 90% within its impedance matching bandwidth.
A Circular-Ring Monopole Antenna with a Half-Circular Ring and Ground Slot for WLAN/WiMAX Triple-Band Operations
Yoon, Joong Han ; Im, Dae Soo ; Ha, Sung Jae ; Rhee, Young Chul ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 367~375
DOI : 10.5515/JKIEES.2014.14.4.367
In this paper, a novel triple-band circular-ring monopole antenna with a half-circular ring and ground slot for wireless local area network/Worldwide Interoperability of Microwave Access (WLAN/WiMAX) applications is proposed. The proposed antenna consists of one circular ring, a half-circular ring and a rectangular slot in the ground plane. Based on the concept, a prototype of the proposed triple-band antenna was designed, fabricated and tested. The numerical and experiment results demonstrated that the proposed antenna satisfied the -10 dB impedance bandwidth requirement while simultaneously covering the WLAN and WiMAX bands. Furthermore, this paper presents and discusses the 2D radiation patterns and 2D gains according to the results of the experiment.
Slew-Rate Enhanced Low-Dropout Regulator by Dynamic Current Biasing
Jeong, Nam Hwi ; Cho, Choon Sik ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 376~381
DOI : 10.5515/JKIEES.2014.14.4.376
We present a CMOS rail-to-rail class-AB amplifier using dynamic current biasing to improve the delay response of the error amplifier in a low-dropout (LDO) regulator, which is a building block for a wireless power transfer receiver. The response time of conventional error amplifiers deteriorates by slewing due to parasitic capacitance generated at the pass transistor of the LDO regulator. To enhance slewing, an error amplifier with dynamic current biasing was devised. The LDO regulator with the proposed error amplifier was fabricated in a
high-voltage BCDMOS process. We obtained an output voltage of 4 V with a range of input voltages between 4.7 V and 7 V and an output current of up to 212 mA. The settling time during line transient was measured as
for an input variation of 4.7-6 V. In addition, an output capacitor of 100 pF was realized on chip integration.
Material Properties Characterization Based on Measurements of Reflection Coefficient and Bandwidth
Nguyen, Phuong Minh ; Chung, Jae-Young ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 382~386
DOI : 10.5515/JKIEES.2014.14.4.382
The knowledge of substrate material properties is important in antenna design. We present a technique to accurately characterize the dielectric constant and loss tangent of an antenna substrate based on the measurements of antenna's reflection coefficient and bandwidth. In this technique, an error function is formulated by combinations of the reflection coefficient and bandwidth of measured and simulated data, and then an optimization technique is used to efficiently search for the substrate properties that minimize the error function. The results show that the method is effective in retrieving the dielectric constant and loss tangent of the antenna substrate without the need of additional test fixtures as in conventional substrate characterization methods.
Size and Harmonic Reduced Wilkinson Balun Using Parallel Coupled Line with Open Stub
Lee, Won-Kyun ; Hwang, Hee-Yong ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 387~392
DOI : 10.5515/JKIEES.2014.14.4.387
In this paper, a size-reduced Wilkinson balun with wide harmonic-suppressed band is presented. An accurate analysis of the parallel coupled line with an open stub (PCL-OS) is carried out. The PCL-OS structure shows excellent low pass filter and harmonic-suppression characteristics, which is useful for designing a low pass filter unit cell (LUC) with a reduced size. The designed Wilkinson balun at a 2.45 GHz center frequency not only shows an excellent harmonic suppression including the 5th harmonics up to 14 GHz over 15 dB, but it also has an area reduced to 48% of the conventional one.
A Highly Efficient Dual-Mode 3G/4G Linear CMOS Stacked-FET Power Amplifier Using Active-Bypass
Kim, Unha ; Kim, Yong-Gwan ; Woo, Jung-Lin ; Park, Sunghwan ; Kwon, Youngwoo ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 393~398
DOI : 10.5515/JKIEES.2014.14.4.393
A highly efficient dual-mode linear CMOS stacked-FET power amplifier (PA) is implemented for 3G UMTS and 4G LTE handset applications. High efficiency is achieved at a backed-off output power (
) below 12 dBm by employing an active-bypass amplifier, which consumes very low quiescent current and has high load-impedance. The output paths between high- and low-power modes of the PA are effectively isolated by using a bypass switch, thus no RF performance degradation occurs at high-power mode operation. The fabricated 900 MHz CMOS PA using a silicon-on-insulator (SOI) CMOS process operates with an idle current of 5.5 mA and shows power-added efficiency (PAE) of 20.5%/43.5% at
= 12.4 / 28.2 dBm while maintaining an adjacent channel leakage ratio (ACLR) better than -39 dBc, using the 3GPP uplink W-CDMA signal. The PA also exhibits PAE of 35.1% and
of -33 dBc at
= 26.5 dBm, using the 20 MHz bandwidth 16-QAM LTE signal.
Highly Linear 2-Stage Doherty Power Amplifier Using GaN MMIC
Jee, Seunghoon ; Lee, Juyeon ; Kim, Seokhyeon ; Park, Yunsik ; Kim, Bumman ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 399~404
DOI : 10.5515/JKIEES.2014.14.4.399
A power amplifier (PA) for a femto-cell base station should be highly efficient, linear and small. The efficiency for amplification of a high peak-to-average power ratio (PAPR) signal was improved by designing an asymmetric Doherty PA (DPA). The linearity was improved by applying third-order inter-modulation (IM3) cancellation method. A small size is achieved by designing the DPA using GaN MMIC process. The implemented 2-stage DPA delivers a power-added efficiency (PAE) of 38.6% and a gain of 33.4 dB with an average power of 34.2 dBm for a 7.2 dB PAPR 10 MHz bandwidth LTE signal at 2.14 GHz.
Target-to-Clutter Ratio Enhancement of Images in Through-the-Wall Radar Using a Radiation Pattern-Based Delayed-Sum Algorithm
Lim, Youngjoon ; Nam, Sangwook ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 405~410
DOI : 10.5515/JKIEES.2014.14.4.405
In this paper, we compare the quality of images reconstructed by a conventional delayed-sum (DS) algorithm and radiation pattern-based DS algorithm. In order to evaluate the quality of images, we apply the target-to-clutter ratio (TCR), which is commonly used in synthetic aperture radar (SAR) image assessment. The radiation pattern-based DS algorithm enhances the TCR of the image by focusing the target signals and preventing contamination of the radar scene. We first consider synthetic data obtained through GprMax2D/3D, a finite-difference time-domain (FDTD) forward solver. Experimental data of a 2-GHz bandwidth stepped-frequency signal are collected using a vector network analyzer (VNA) in an anechoic chamber setup. The radiation pattern-based DS algorithm shows a 6.7-dB higher TCR compared to the conventional DS algorithm.
High-Isolation SPDT RF Switch Using Inductive Switching and Leakage Signal Cancellation
Ha, Byeong Wan ; Cho, Choon Sik ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 411~414
DOI : 10.5515/JKIEES.2014.14.4.411
A switch is one of the most useful circuits for controlling the path of signal transmission. It can be added to digital circuits to create a kind of gate-level device and it can also save information into memory. In RF subsystems, a switch is used in a different way than its general role in digital circuits. The most important characteristic to consider when designing an RF switch is keeping the isolation as high as possible while also keeping insertion loss as low as possible. For high isolation, we propose leakage signal cancellation and inductive switching for designing a singlepole double-throw (SPDT) RF switch. By using the proposed method, an isolation level of more than 23 dB can be achieved. Furthermore, the heterojunction bipolar transistor (HBT) process is used in the RF switch design to keep the insertion loss low. It is demonstrated that the proposed RF switch has an insertion loss of less than 2 dB. The RF switch operates from 1 to 8 GHz based on the
SiGe HBT process, taking up an area of
An Equivalent Circuit Model for a Dumbbell-Shaped DGS Microstrip Line
Woo, Duk-Jae ; Lee, Taek-Kyung ;
Journal of electromagnetic engineering and science, volume 14, issue 4, 2014, Pages 415~418
DOI : 10.5515/JKIEES.2014.14.4.415
This paper presents an equivalent circuit model for a dumbbell-shaped defected ground structure (DGS) in a microstrip line. The effects of equivalent circuit elements of a dumbbell-shaped DGS and their magnetic coupling to the host transmission line are modeled as a simple lumped-element circuit. In addition, simple approximate expressions to determine the main circuit parameters for this model are presented. The transfer characteristic calculated by the proposed circuit model is compared with the results of EM simulation and measurement.