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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
Editor in Chief :
Volume & Issues
Volume 13, Issue 4 - Dec 2013
Volume 13, Issue 3 - Sep 2013
Volume 13, Issue 2 - Jun 2013
Volume 13, Issue 1 - Mar 2013
Selecting the target year
Development of Ultra-Wideband Antennas
Chen, Zhi Ning ;
Journal of electromagnetic engineering and science, volume 13, issue 2, 2013, Pages 63~72
DOI : 10.5515/JKIEES.2013.13.2.63
The ultra-wideband (UWB) spectrum available for commercial applications has offered us an opportunity to achieve high-speed wireless communications and high-accuracy location applications. As one of key research areas in UWB technology, a lot of innovative broadband and miniaturization techniques for UWB antennas have been greatly invented and developed for years. This paper reviews the development of UWB antenna design in the past decade. Starting with a brief introduction of the specific requirements and promising applications of UWB systems, the unique design challenges of UWB antennas are highlighted. Next, the important milestones of UWB antenna designs are briefed. After that, a variety of planar UWB antennas invented for broadband operation, miniaturization, and multiple functions are introduced. Last, the comments on the development of UWB antennas in future are shared.
Application of Transformation Electromagnetics to Cloak Design and Reduction of Radar Cross Section
Mittra, Raj ; Zhou, Yuda ;
Journal of electromagnetic engineering and science, volume 13, issue 2, 2013, Pages 73~85
DOI : 10.5515/JKIEES.2013.13.2.73
In this paper we present an alternative approach to addressing the problem of designing cloaks for radar targets, which have been dealt with in the past by using the transformation optics (TO) algorithm. The present design utilizes realistic materials, which can be fabricated in the laboratory, and are wideband as well as relatively insensitive to polarization and incident angle of the incoming wave. The design strategy, presented herein, circumvents the need to use metamaterials for cloak designs that are inherently narrowband, dispersive and highly sensitive to polarization and incident angle. A new interpretation of the TO algorithm is presented and is employed for the design of radar cross section-reducing absorbers for arbitrary targets, and not just for canonical shapes, e.g., cylinders. The topic of performance enhancement of the absorbers by using graphene materials and embedded frequency structure surfaces is briefly mentioned. The design procedure for planar absorbing covers is presented and their performance as wrappers of general objects is discussed. A number of test cases are included as examples to illustrate the application of the proposed design methodology, which is a modification of the classical TO paradigm.
Definition of Antenna Diversity Gain in User-Distributed 3D-Random Line-of-Sight
Kildal, Per-Simon ; Carlberg, Ulf ; Carlsson, Jan ;
Journal of electromagnetic engineering and science, volume 13, issue 2, 2013, Pages 86~92
DOI : 10.5515/JKIEES.2013.13.2.86
The present paper defines diversity gain for stationary users. This deals in particular with gathering the received signal statistics over possible user positions and orientations in space rather than over time, and to define a meaningful diversity gain related to the cumulative improvement of the performances of the 1% users with the worst receiving conditions. The definition is used to evaluate diversity gain for some typical small antennas in an extreme environment with only line-of-sight (LOS). The LOS environment is regarded as user-distributed 3D-random LOS caused by the statistics of an ensemble of stationary users with arbitrary orientations in the horizontal plane (2D), and with arbitrary orientations of their wireless devices in the vertical plane. Thus, an overall 3D-random distribution of user orientation is assumed.
Harmonic Suppressed Dual-Band Bandpass Filter with Independently Tunable Center Frequencies and Bandwidths
Chaudhary, Girdhari ; Jeong, Yongchae ; Lim, Jongsik ;
Journal of electromagnetic engineering and science, volume 13, issue 2, 2013, Pages 93~103
DOI : 10.5515/JKIEES.2013.13.2.93
This paper presented a novel approach for the design of a tunable dual-band bandpass filter (BPF) with independently tunable passband center frequencies and bandwidths. The newly proposed dual-band filter principally comprised two dual-mode single band filters using common input/output lines. Each single BPF was realized using a varactor-loaded transmission line resonator. To suppress the harmonics over a broad bandwidth, a defected ground structure was used at the input/output feeding lines. From the experimental results, it was found that the proposed filter exhibited the first passband center frequency tunable range from 1.48 to 1.8 GHz with a 3-dB fractional bandwidth (FBW) variation from 5.76% to 8.55%, while the second passband center's frequency tunable range was 2.40 to 2.88 GHz with a 3-dB FBW variation from 8.28% to 12.42%. The measured results of the proposed filters showed a rejection level of 19 dB up to more than 10 times the highest center frequency of the first passband.
Design of Miniaturized Dual-Band Artificial Magnetic Conductor with Easy Control of Second/First Resonant Frequency Ratio
Ta, Son Xuat ; Park, Ikmo ;
Journal of electromagnetic engineering and science, volume 13, issue 2, 2013, Pages 104~112
DOI : 10.5515/JKIEES.2013.13.2.104
A novel miniaturized artificial magnetic conductor (AMC) is proposed for dual-band operation. An AMC unit cell that employs four slots in the metallic patch is used to achieve miniaturization as well as easy control of the second/first resonant frequency ratio, which can be varied from 1.5 to 3.26 by simply changing the slot shape for a given metallic patch size. A dual-band antenna composed of a wideband monopole suspended over the proposed AMC surface is designed and tested to validate this approach. The measurements result in a satisfactory and good matching condition for the dual-band antenna.
Realization of High Impedance Surface Characteristics Using a Periodically Transformed Artificial Magnetic Conductor Structure and Reduction Technique of Specific Absorption Rate
Lee, Seungwoo ; Rhee, Seung-Yeop ; Kim, Pan-Yeol ; Kim, Nam ;
Journal of electromagnetic engineering and science, volume 13, issue 2, 2013, Pages 113~119
DOI : 10.5515/JKIEES.2013.13.2.113
We developed a transformed, symmetrical, mushroom-like surface without via holes in cells focused on a 2.4-GHz WLAN band. Each slot in the novel type structure plays a key role in modeling at the desired frequencies. The designed artificial magnetic conductor (AMC) has several advantages, including a small size, a wider bandwidth, a short reflecting distance to the antenna, and easy fabrication because there are no via holes. Overall dimensions of the AMC cell are 21 mm
(Thickness), and the bandwidth is about three times wider (11.7%) compared to that of a conventional AMC (4.0%). For evaluating the performance of the proposed structure, a reflector, which periodically consists of the designed AMC cells, was developed. The antenna with the investigated AMC reflector not only works within a quarter of the wavelength because of the extremely high wave impedance generated by the AMC cells on the surface of the structure but also reduces the specific absorption rate (SAR). Electromagnetic field (EMF) exposure to a human phantom was analyzed by applying the designed reflector to the 2.4-GHz dipole antenna in a tablet PC. The calculated peak SAR averaged over 1 g was 0.125 W/kg when the input power was 1 W and the antenna was located at 20 cm from the human phantom. However, the SAR value was only 0.002 W/kg (i.e., 98.4% blocked) when the designed reflector was inserted in front of the antenna.
Compact Rotman Lens with Size-Reduced Transition Structures between the Lens Body and the Connecting Lines
Lee, Woosung ; Kim, Youngsub ; Kim, Jaeheung ; Yoon, Young Joong ;
Journal of electromagnetic engineering and science, volume 13, issue 2, 2013, Pages 120~126
DOI : 10.5515/JKIEES.2013.13.2.120
This paper introduces a new design for a Rotman lens that has been proposed to minimize its size and provide a suitable design for a compact beamforming system. The size reduction is realized by minimizing the length of the transition structures, which are positioned between the lens body and the connecting lines. The proposed structure is much shorter than a conventional transition structure, which is a tapered line in general. As a result, a 45% size reduction can be achieved by using the proposed transition structure, compared to a typical Rotman lens with linearly tapered lines. Therefore, the proposed Rotman lens will be suitable for compact beamforming systems.
Scaling Rules for Multi-Finger Structures of 0.1-μm Metamorphic High-Electron-Mobility Transistors
Ko, Pil-Seok ; Park, Hyung-Moo ;
Journal of electromagnetic engineering and science, volume 13, issue 2, 2013, Pages 127~133
DOI : 10.5515/JKIEES.2013.13.2.127
We examined the scaling effects of a number of gate_fingers (N) and gate_widths (w) on the high-frequency characteristics of
metamorphic high-electron-mobility transistors. Functional relationships of the extracted small-signal parameters with total gate widths (
) of different N were proposed. The cut-off frequency (
) showed an almost independent relationship with
; however, the maximum frequency of oscillation (
) exhibited a strong functional relationship of gate-resistance (
) influenced by both N and
. A greater
produced a higher
; but, to maximize
at a given
, to increase N was more efficient than to increase the single gate_width.
Simplified Modeling of Ring Resonators and Split Ring Resonators Using Magnetization
Jeon, Dongho ; Lee, Bomson ;
Journal of electromagnetic engineering and science, volume 13, issue 2, 2013, Pages 134~136
DOI : 10.5515/JKIEES.2013.13.2.134
This paper examines various aspects of the electromagnetic responses of the ring resonator located in the transverse electromagnetic cell. In addition, an equivalent circuit for the ring resonator is proposed and analyzed based on the electromagnetic phenomenon of the resonator. The equivalent circuit was simply modeled based on the concept of magnetization. A method for achieving a wider operating bandwidth of the negative permeability is provided. The ring resonator with its resonant frequency of 13.56 MHz was designed and its characteristics were examined in terms of S-parameters, effective permeability, loss rate, bandwidth, etc. The circuit and electromagnetic simulation results show an excellent agreement as well as that of theory.
Compact Metamaterial-Based Tunable Phase Shifter at 2.4 GHz
Jung, Youn-Kwon ; Lee, Bomson ;
Journal of electromagnetic engineering and science, volume 13, issue 2, 2013, Pages 137~139
DOI : 10.5515/JKIEES.2013.13.2.137
A compact metamaterial (MTM)-based tunable phase shifter consisting of four unit cells with a simple DC bias circuit has been designed at 2.4 GHz. The variable series capacitors and shunt inductors that are required to be loaded periodically onto a host transmission line are realized employing only chip variable capacitors (varactors). In addition, the proposed phase shifter requires only one DC bias source to control the varactors, with the matching condition of the MTM line automatically satisfied. The measured phase shifting range is
). The measured insertion loss is approximately 1.5 dB. The circuit/electromagnetic-simulated and measured results are in good agreement.