• Title/Summary/Keyword: Electromagnetic waves absorber

Search Result 16, Processing Time 0.024 seconds

Analysis of Electromagnetic Wave Absorbers for Applying Magnetic Levitation (자기부상체 적용을 위한 전자파 흡수체의 특성 분석)

  • Seo, Yong-beom;Kang, Hyun-il
    • The Transactions of the Korean Institute of Electrical Engineers P
    • /
    • v.65 no.1
    • /
    • pp.13-17
    • /
    • 2016
  • EMC (Electro Magnetic Compatibility) of the electrical railway must be ensured for safety of passenger. Maglev trains has not friction between the wheels and the rails because levitation by an permanent magnets, electromagnets and superconducting magnets etc. So, it is advantageous to maintain a high speed without noise and vibrations. In this paper, we investigated that the magnetic field of the before and after installation electromagnetic waves absorber in order to analyze the effects of electromagnetic waves. The theoretical analysis of the electromagnetic wave absorber was simulated using finite element method. The magnetic field properties of electromagnetic waves absorber were measured by EMI (Electro Magnetic Interference) test receiver.

Electromagnetic Wave Absorber Sheet for 940 MHz Dedicated Short Range Communication Frequency Bands Using Fe Based Alloy Soft Magnetic Metal Powder (Fe-계 연자성 금속분말을 이용한 940 MHz 단거리 전용 통신 (DSRC) 대역 전파 흡수체)

  • Kim, ByeongCheol;Seo, ManCheol;Yun, Yeochun
    • Korean Journal of Materials Research
    • /
    • v.29 no.6
    • /
    • pp.363-370
    • /
    • 2019
  • The recent development of information and communication technologies brings new changes to automobile traffic systems. The most typical example is the advancement of dedicated short range communication(DSRC). DSRC mainly consists of an intelligent transportation system(ITS), an electronic toll collection system(ETCS) and an advanced traveler information system(ATIS). These wireless communications often cause unnecessary electromagnetic waves, and these electromagnetic waves, in turn, cause frequent system malfunction. To solve this problem, an absorber of electromagnetic waves is suggested. In this research, various materials, such as powdered metal and iron oxides, are used to test the possibility for an effective absorption of the unnecessary electromagnetic waves. The various metal powders are made into a thin sheet form by compositing through processing. The electromagnetic characteristics(complex permittivity, complex permeability) of the fabricated sheet are measured. As a result, we achieve -6.5 dB at 940 MHz(77.6 % absorption rate) with a 1.0 mm-thickness electromagnet wave absorber, and -9.5 dB at 940 MHz(88.8 % absorption rate) with a 2.0 mm-thickness absorber.

Broad-Band Design of Ferrite One-body EM Wave Absorbers for an Anechoic Chamber

  • Kim, Dong-Il;Son, June-Young;Park, Woo-Keun;Park, Dong-Han
    • Journal of electromagnetic engineering and science
    • /
    • v.4 no.2
    • /
    • pp.51-55
    • /
    • 2004
  • With the progress of the electronics industry and radio communication technology, certain problems, such as electromagnetic interference(EMI), have arisen due to the increased use of electromagnetic(EM) waves. International organizations such as CISPR, FCC, and ANSI have provided the standards for the EM wave environment and for the countermeasure of the electromagnetic compatibility(EMC). EM wave absorbers are used for constructing an anechoic chamber to test and measure EMI and electromagnetic susceptibility(EMS). In this paper, we have designed an one-body EM(electromagnetic) wave ferrite absorber, based on the equivalent material constants method for both normally and obliquely incident waves, whose absorption abilities are superior to that of the conventional ones. The fabricated absorber has a thickness of 27.68 mm and shows an absorption ability over 20 ㏈ in the frequency from 30 MHz to 6 ㎓.

Metamaterial Perfect Absorber Technology for Leading the Fourth Industrial Revolution (4차 산업혁명을 선도할 메타물질 완전흡수체 기술 동향)

  • Hong, S.H.;Kim, M.H.;Yun, H.W.
    • Electronics and Telecommunications Trends
    • /
    • v.32 no.6
    • /
    • pp.1-7
    • /
    • 2017
  • A metamaterial is a material engineered to have a property that does not exist in nature. A designable material property can be achieved by tailoring its structure, and thus a metamaterial is a novel ICT material and component technology that can break through the limitations of conventional technologies. Among the metamaterials available, a perfect metamaterial absorber is a technology that can nearly absorb light, sound waves, thermal waves, and electromagnetic waves with a simple structure, and has been of significant interest in energy, display, sensor, stealth, and military applications, with wavelengths from visible light to microwaves. In this article, we introduce a brief description of metamaterial absorber technology, the critical issues for its application, as well as ETRI's developed metamaterial absorber technology and its prospects for future use.

Design of Broad-Band Ferrite Absorber in Square Projection Type (기둥형 돌기부를 가지는 광대역 페라이트 전파흡수체의 설계)

  • 김동일;박종구;도상열;김하근;전상엽;박정수;박태원;정세모
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
    • /
    • 1999.05a
    • /
    • pp.432-436
    • /
    • 1999
  • The development of Electromagnetic Communication technology have made our life abundant. However, the countermeasure of EMI(Electromagnetic Interference) are more important socially as increase of a main cause on electromagnetic waves occurrence. It is required that the absorbing ability of an electromagnetic wave absorber is above 20 dB, the bandwidth of which is required from 30 MHz to 1,000 MHz for satisfying the international standard about EMI and also will be required from 30 MHz up to 5,000 MHz in the bandwidth. In this paper, we proposed the square projection type absorber satisfying the above requirements and carried out broadband design using the equivalent material constants method.

  • PDF

Dielectric/Magnetic Nanowires Synthesized by the Electrospinning Method for Use as High Frequency Electromagnetic Wave Absorber

  • Jwa, Yong-Ho
    • Proceedings of the Materials Research Society of Korea Conference
    • /
    • 2009.11a
    • /
    • pp.14-14
    • /
    • 2009
  • High frequency electromagnetic(EM) waves are increasingly being applied in industries because of saturationat lower frequency bands as a result of huge demand. However, electromagneticinterference (EMI) has become a serious problem, and as a result, highfrequency EM absorbers are now being extensively studied. Also, recentdevelopments in absorber technology have focused on producing absorbers thatare thin, flexible, and strong. Hence, one-dimension ferrous nano-materials area potential research field, because of their interesting electronic andmagnetic properties. Commercially, EM wave absorbing products are made ofcomposites, which blend the insulating polymer with magnetic fillers. Inparticular, the shape of the magnetic fillers, such flaky, acicular, or fibrousmagnetic metal particles, rather than spherical, is essential for synthesizingthin and lightweight EM wave absorbers with higher permeability. High aspectratio materials exhibit a higher permeability value and therefore betterabsorption of the EM wave, because of electromagnetic anisotropy. Nanowires areusually fabricated by drawing, template synthesis, phase separation, selfassembly, and electrospinning with a thermal treatment and reduction process.Producing nanowires by the electrospinning method involves a conventionalsol-gel process that is simple, unique, and cost-effective. In thispresentation, Magnetic nanowire and dielectric materials coated magneticnanowire with a high aspect ratio were successfully synthesized by theelectrospinning process with heat treatment and reduction. In addition toestimating the EM wave absorption ability of the synthesized magnetic anddielectric materials coated magnetic nanowire with a network analyzer, weinvestigated the possibility of using these nanowires as high-frequency EM waveabsorbers. Furthermore, a wide variety of topics will be discussed such as thetransparent conducting nanowire and semiconducting nanowire/tube with theelectrospinning process.

  • PDF

Characteristics of Electromagnetic Wave Absorber Sheet for 2.4 GHz Wireless Communication Frequency Bands Using Fe Based Alloy Soft Magnetic Metal Powder (Fe-계 연자성 금속분말을 이용한 2.4 GHz 대역 무선통신용 전파 흡수체의 특성 평가)

  • Kim, ByeongCheol;Seo, ManCheol;Yun, Yeochun
    • Korean Journal of Materials Research
    • /
    • v.29 no.9
    • /
    • pp.532-541
    • /
    • 2019
  • Information and communication technologies are developing rapidly as IC chip size becomes smaller and information processing becomes faster. With this development, digital circuit technology is being widely applied to mobile phones, wireless LANs, mobile terminals, and digital communications, in which high frequency range of GHz is used. In high-density electronic circuits, issues of noise and EMC(Electro-Magnetic Compatibility) arising from cross talk between interconnects or devices should be solved. In this study, sheet-type electromagnetic wave absorbers that cause electromagnetic wave attenuation are fabricated using composites based on soft magnetic metal powder and silicon rubber to solve the problem of electromagnetic waves generated in wireless communication products operating at the frequency range of 2.4 GHz. Sendust(Fe-Si-Al) and carbonyl iron(Fe-C) were used as soft magnetic metals, and their concentrations and sheet thicknesses were varied. Using soft magnetic metal powder, a sheet is fabricated to exhibit maximum electromagnetic attenuation in the target frequency band, and a value of 34.2dB(99.9 % absorption) is achieved at the target frequency.

Ultra-thin Polarization Independent Absorber Using Hexagonal Interdigital Metamaterial

  • Lee, Joung-Young;Yoon, Young-Joong;Lim, Sung-Joon
    • ETRI Journal
    • /
    • v.34 no.1
    • /
    • pp.126-129
    • /
    • 2012
  • An ultra-thin hexagonal microwave metamaterial absorber is described. It can absorb any polarized transverse electromagnetic wave because of its hexagonal shape. In spite of its very thin structure, almost $0.028{\lambda}g$, the absorber achieved 99% absorptivity at 11.35 GHz in experimental results because of the increased coupling losses, showing good agreement with simulation results. In addition, this high absorbance is unchanged for any polarized waves with the same frequency.

Design of Metamaterial-Inspired Wideband Absorber at X-Band Adopting Trumpet Structures

  • Kim, Beom-Kyu;Lee, Bomson
    • Journal of electromagnetic engineering and science
    • /
    • v.14 no.3
    • /
    • pp.314-316
    • /
    • 2014
  • This letter presents two types of metamaterial-inspired absorbers adopting resistive trumpet structures at the X band. The unit cell of the first type is composed of a trumpet-shaped resonator loading a chip resistor, a metallic back plane, and a FR4 (${\varepsilon}_r=4.4-j0.02$) substrate between them (single-layer). The absorption rate is 99.5% at 13.3 GHz. The full width at half maximum (FWHM) is 95 % at 11.2 GHz (from 5.9 to 16.5 GHz). The size of unit cell is $5.6{\times}5.6{\times}2.4mm^3$. The second type has been optimized with a $7{\Omega}$/square uniform resistive coating, removing the chip resistors but leading to results comparable to the first type. The proposed absorbers are almost insensitive to polarizations of incident waves due to symmetric geometry.

A Study on Development of Ferrite Wave Absorber with Cutting Corn-Shaped Type (원추절단형 폐라이트 전파흡수체의 최적설계 및 제작에 관한 연구)

  • 김동일;박종구;정세모;이영구
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
    • /
    • 2000.10a
    • /
    • pp.153-156
    • /
    • 2000
  • The remarkable progress of electronics and radio communications technology has made our life abundant. On the other hand, the countermeasure of EMC becomes more important socially according to the increased use of electromagnetic waves. It had been required that the absorbing ability of an electromagnetic wave absorber is more than 20 dB, the bandwidth of which is required through 30 MHz to 1,000 MHz for satisfying the international standard about an anechoic chamber for EMI/EMS measurement. From November of 1998, however, the CISPR11 has accepted the extended frequency band from 30 MHz to 18 GHz in the bandwidth of EMI measurement. In this paper, we proposed the cutting com-shaped type satisfying the above requirments and carried out broadband design using the equivalent material constants method. Moreover, we have fabricated it and compared its characteristics with simulated one.

  • PDF