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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
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 15, Issue 4 - Oct 2015
Volume 15, Issue 3 - Jul 2015
Volume 15, Issue 2 - Apr 2015
Volume 15, Issue 1 - Jan 2015
Selecting the target year
Design of an Advanced CMOS Power Amplifier
Kim, Bumman ; Park, Byungjoon ; Jin, Sangsu ;
Journal of electromagnetic engineering and science, volume 15, issue 2, 2015, Pages 63~75
DOI : 10.5515/JKIEES.2015.15.2.63
The CMOS power amplifier (PA) is a promising solution for highly-integrated transmitters in a single chip. However, the implementation of PAs using the CMOS process is a major challenge because of the inferior characteristics of CMOS devices. This paper focuses on improvements to the efficiency and linearity of CMOS PAs for modern wireless communication systems incorporating high peak-to-average ratio signals. Additionally, an envelope tracking supply modulator is applied to the CMOS PA for further performance improvement. The first approach is enhancing the efficiency by waveform engineering. In the second approach, linearization using adaptive bias circuit and harmonic control for wideband signals is performed. In the third approach, a CMOS PA with dynamic auxiliary circuits is employed in an optimized envelope tracking (ET) operation. Using the proposed techniques, a fully integrated CMOS ET PA achieves competitive performance, suitable for employment in a real system.
Negative Group Delay Circuit with Improved Signal Attenuation and Multiple Pole Characteristics
Chaudhary, Girdhari ; Jeong, Junhyung ; Kim, Phirun ; Jeong, Yongchae ;
Journal of electromagnetic engineering and science, volume 15, issue 2, 2015, Pages 76~81
DOI : 10.5515/JKIEES.2015.15.2.76
This paper presents a design of a transmission line negative group delay (NGD) circuit with multiple pole characteristics. By inserting an additional transmission line into a conventional NGD circuit, the proposed circuit provides further design parameters to obtain wideband group delay (GD) and to help reduce signal attenuation. As a result, the number of gain compensating amplifiers can be reduced, which can contribute to stable operation when integrated into RF systems. The multiple pole characteristics can provide wider NGD bandwidth and can be obtained by connecting resonators with slightly different center frequencies separated by quarter-wavelength transmission lines. For experimental validation, an NGD circuit with two poles GD characteristic is designed, simulated, and measured.
A 2.4 GHz-Band 100 W GaN-HEMT High-Efficiency Power Amplifier for Microwave Heating
Nakatani, Keigo ; Ishizaki, Toshio ;
Journal of electromagnetic engineering and science, volume 15, issue 2, 2015, Pages 82~88
DOI : 10.5515/JKIEES.2015.15.2.82
The magnetron, a vacuum tube, is currently the usual high-power microwave power source used for microwave heating. However, the oscillating frequency and output power are unstable and noisy due to the low quality of the high-voltage power supply and low Q of the oscillation circuit. A heating system with enhanced reliability and the capability for control of chemical reactions is desired, because microwave absorption efficiency differs greatly depending on the object being heated. Recent studies on microwave high-efficiency power amplifiers have used harmonic processing techniques, such as class-F and inverse class-F. The present study describes a high-efficiency 100 W GaN-HEMT amplifier that uses a harmonic processing technique that shapes the current and voltage waveforms to improve efficiency. The fabricated GaN power amplifier obtained an output power of 50.4 dBm, a drain efficiency of 72.9%, and a power added efficiency (PAE) of 64.0% at 2.45 GHz for continuous wave operation. A prototype microwave heating system was also developed using this GaN power amplifier. Microwaves totaling 400 W are fed from patch antennas mounted on the top and bottom of the microwave chamber. Preliminary heating experiments with this system have just been initiated.
Common Mode Noise Reduction for an LLC Resonant Converter by Using Passive Noise Cancellation
Ryu, Younggon ; Kim, Sungnam ; Jeong, Geunseok ; Park, Jaesu ; Kim, Duil ; Park, Jongwook ; Kim, Jingook ; Han, Ki Jin ;
Journal of electromagnetic engineering and science, volume 15, issue 2, 2015, Pages 89~96
DOI : 10.5515/JKIEES.2015.15.2.89
This paper describes the application of a passive noise cancellation method to a prototype inductor-inductor-capacitor (LLC) resonant converter by placing a compensation winding in a transformer to reduce common mode noise. The connection method for the compensation winding is investigated. A circuit analysis is implemented for the displacement currents between the primary and secondary windings in the transformer. The analyzed displacement currents are verified by performing a circuit simulation and a proper compensation winding connection that reduces common mode noise is found. The measurement results show that common mode noise is reduced effectively up to 20 dB in the 1 to 7 MHz frequency region for the prototype LLC resonant converter by using the proposed passive noise cancellation method.
Analysis of Absorption Loss by a Human Body in On-to-Off Body Communication at 2.45 GHz
Jeon, Jaesung ; Lee, Sangwoo ; Choi, Jaehoon ; Kim, Sunwoo ;
Journal of electromagnetic engineering and science, volume 15, issue 2, 2015, Pages 97~103
DOI : 10.5515/JKIEES.2015.15.2.97
This paper investigates the effect of absorption loss by a human body to the received signal strength with respect to on-body transmitting antenna positions in on-to-off wireless body area networks. This investigation is based on measurement results obtained from experiments performed on human bodies (male and female) using planar inverted-F antennas in an anechoic chamber. The total absorption loss by the human body is also presented through the SEMCAD-X simulations. Our investigation showed that the received signal strength becomes lower when the transmitting antenna is mounted at a specific position where more absorption loss is experienced. The statistical analyses of on-to-off body channel characteristics based on the measurement results are presented.
Magnetic Resonance-Based Wireless Power Transmission through Concrete Structures
Kim, Ji-Min ; Han, Minseok ; Sohn, Hoon ;
Journal of electromagnetic engineering and science, volume 15, issue 2, 2015, Pages 104~110
DOI : 10.5515/JKIEES.2015.15.2.104
As civil infrastructures continue to deteriorate, the demand for structural health monitoring (SHM) has increased. Despite its outstanding capability for damage identification, many conventional SHM techniques are restricted to huge structures because of their wired system for data and power transmission. Although wireless data transmission using radio-frequency techniques has emerged vis-
-vis wireless sensors in SHM, the power supply issue is still unsolved. Normal batteries cannot support civil infrastructure for no longer than a few decades. In this study, we develop a magnetic resonance-based wireless power transmission system, and its performance is validated in three different mediums: air, unreinforced concrete, and reinforced concrete. The effect of concrete and steel rebars is analyzed.
A Dual-Band Gap-Filler Antenna Design with a Phi-Shaped Slot
Park, Sang Yong ; Park, Jong Kweon ;
Journal of electromagnetic engineering and science, volume 15, issue 2, 2015, Pages 111~114
DOI : 10.5515/JKIEES.2015.15.2.111
In this paper, we have proposed dual-band Phi-shaped slot gap filler antenna for satellite internet service applications. Some properties of the antenna such as return loss, radiation pattern, and gain have been simulated and measured. The proposed antenna has a Phi-shaped slot on the circular patch and is fabricated on the TLX-9 substrate. The radius of the circular patch is 25 mm, and it has a coaxial feeding structure. The dual-band Phi-shaped slot gap filler antenna has high-gain, small-size, simple-structure, and good radiation patterns at each band. The operating frequency band can be tuned by adjusting the length AL and FL of the Phi-shaped slot.
A Polarization Diversity Patch Antenna with a Reconfigurable Feeding Network
Lee, Sung Woo ; Sung, Youngje ;
Journal of electromagnetic engineering and science, volume 15, issue 2, 2015, Pages 115~119
DOI : 10.5515/JKIEES.2015.15.2.115
This paper proposes a reconfigurable square-patch antenna with polarization diversity. The proposed antenna consists of a square radiating patch and a Y-shaped feed structure with two PIN diodes. The shape of the feed structure can be changed by adjusting the bias states of the two PIN diodes, which helps switch between two orthogonal linear polarizations. The polarization diversity characteristic is validated by the simulated current distribution and the measured radiation pattern.
Effect of Loading Split-Ring Resonators in a Microstrip Antenna Ground Plane
Lee, Hong-Min ;
Journal of electromagnetic engineering and science, volume 15, issue 2, 2015, Pages 120~122
DOI : 10.5515/JKIEES.2015.15.2.120
This study presents a new, simple method for improving the front-to-back (F/B) ratio of a microstrip patch antenna (MSA) based on surface wave suppression. The back radiation of the MSA is significantly reduced by using the meandered ground plane edges and placing split-ring resonators (SRRs) in the middle of the meandered slots. By loading SRRs near the center of the meandered ground plane edges, some parts of the diffracted back-lobe power density can be reduced further. Compared to the F/B ratio of a conventional MSA with a full ground plane of the same size, an improved F/B ratio of 18 dB has been achieved experimentally for our proposed MSA.