• Title, Summary, Keyword: Permittivity

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Electromagnetic Wave Absorption Properties of Fe73Si16B7Nb3Cu1-Based Nanocrystalline Soft Magnetic Powder Composite Mixed with Charcoal Powder (나노결정 Fe73Si16B7Nb3Cu1 연자성분말과 숯분말 혼합 복합성형체의 전자파흡수 특성)

  • Kim, Sun-I;Kim, Mi-Rae;Sohn, Keun-Yong;Park, Won-Wook
    • Journal of Korean Powder Metallurgy Institute
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    • v.16 no.4
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    • pp.291-295
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    • 2009
  • The electromagnetic wave absorption sheets were fabricated by mixing of $Fe_{73}Si_{16}B_7Nb_3Cu_1$ nanocrystalline soft magnetic powder, charcoal powder and polymer based binder. The complex permittivity, complex permeability, and scattering parameter have been measured using a network analyzer in the frequency range of 10 MHz$\sim$10 GHz. The results showed that complex permittivity of sheets was largely dependent on the frequency and the amount of charcoal powder : The permittivity was improved up to 100 MHz, however the value was decreased above 1 GHz. The power loss of electromagnetic wave absorption data showed almost the same tendency as the results of complex permittivity. However, the complex permeability was not largely affected by the frequency, and the values were decreased with the addition of charcoal powder. Based on the results, it can be summarized that the addition of charcoal powder was very effective to improve the EM wave absorption in the frequency range of 10 MHz$\sim$1 GHz.

A Study on Permittivity of Multi-walled Carbon nanotube/Epoxy Composites (다중벽 탄소나노튜브/에폭시 복합재료의 유전율에 관한 연구)

  • 이상의;박기연;김천곤;한재흥
    • Composites Research
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    • v.17 no.3
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    • pp.38-44
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    • 2004
  • The electromagnetic interference (EMI) shielding is very essential for commercial and military purposes. We fabricated multi-walled carbon nanotube (MWNT)/epoxy composites and studied the electromagnetic characteristics of the composites before we study the characteristics of MWNT-added glass fiber-reinforced composites. After setting up the fabrication process, we measured the permittivity of MWNT/epoxy composites with process variables and MWNT concentrations in X-band (8.2GHz~12.4GHz). We also observed re-aggregation phenomenon of MWNTs and investigated its effect on the permittivity. The permittivity of the composites was influenced by the degree of dispersion of MWNTs and increased almost linearly as MWNT concentration increases.

Experimental Extraction of Effective Permittivity on the Structures of Coplanar Waveguides (코프래너 도파로 구조에서 S-파라메터를 이용한 유효유전상수 실험적 도출)

  • 지용
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.41 no.11
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    • pp.15-20
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    • 2004
  • This paper proposed a very simple method of extracting an effective permittivity from the data of scattering parameters measured on the transmission line of coplanar waveguides in the frequency range of microwave or millimeter waves. This is an extracting method of an effective permittivity $\varepsilon$$_{eff}$ in the case of $\beta$$\ell$ =n$\pi$ (n=integer), where the value of S$_{11}$ changes abruptly following the operating frequency. The experimental value of the effective permittivity $\varepsilon$$_{eff}$ on a dielectric substrate of Rogers 4003$^{TM}$ material of $\varepsilon$$_{r}$ =3.38 showed the value of 2.042, which differs in the error of -3.4% to 8% from those calculated from the previously reported formulae. This result showed that the measurement method was very simple, as well as applied directly to the fabricated circuit patterns, even though the circuit patterns might be complicated or on the substrate of different dielectric materials.s.als.

Effects of Magneto-Dielectric Ceramics for Small Antenna Application

  • Kim, Jae-Sik;Lee, Young-Hie;Lee, Byungje;Lee, Jong-Chul;Choi, Jin Joo;Kim, Jin Young
    • Journal of Electrical Engineering and Technology
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    • v.9 no.1
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    • pp.273-279
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    • 2014
  • Hexagonal Ba-ferrites are widely suggested as materials for small antennas. In this paper, the sintering behavior and magneto-electric properties of $Ba_3Co_{2-2x}Mn_{2x}Fe_{24}O_{41}$ ($0.1{\leq}x{\leq}0.5$) ceramics were investigated for small antenna application. All samples of $Ba_3Co_{2-2x}Mn_{2x}Fe_{24}O_{41}$ ceramics were prepared by the solid-state reaction method and sintered at $1250^{\circ}C$. From the XRD patterns of the sintered $Ba_3Co_{2-2x}Mn_{2x}Fe_{24}O_{41}$ceramics, the Z-type phases were found to be the main phases. The real part of permittivity and permeability of the $Ba_3Co_{2-2x}Mn_{2x}Fe_{24}O_{41}$ceramics decreased with frequency. On the other hand, loss tangents of permittivity and permeability tended to behave opposite to real part of permittivity and permeability. The real part of permeability was affected by Mn additions. The real part of permittivity, the loss tangent of permittivity and the real part of permeability, the loss tangent of permeability of $Ba_3Co_{0.2}Mn_{0.8}Fe_{24}O_{41}$ ceramics were 19.774, 0.176 and 15.183, 0.073, respectively, at 510 MHz. In order to investigate the effect of magneto-dielectric ceramics on antenna, PIFA (Planar Inverted F Antenna) was simulated with CST (Computer Simulation Technology). The operating frequency of antenna was decreased without considerable change of bandwidth by using the $Ba_3Co_{0.2}Mn_{0.8}Fe_{24}O_{41}$ ceramics as the carrier.

Permittivity Measurement of Thin Film Using a Waveguide-type Resonator with a Slot (슬랏을 갖는 도파관형 공진기를 이용한 박막 필름의 유전율 측정)

  • Cho, Chihyun;Kang, Jin-Seob;Kim, Jeng-Hwan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.2
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    • pp.214-217
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    • 2013
  • In this paper, a waveguide-type resonator with a slot is proposed to measure permittivity of thin film from resonant frequency shifting by an attached MUT(Material Under Test). The MUT on the slot shifts resonant frequency by perturbation of electromagnetic field. Amount of shifting resonance frequency is dependent on the permittivity of MUT, and that relation is obtained from numerical simulation. The measured relative permittivity of a thin film with thickness of $65{\mu}m$ is 3.3492 with standard error of ${\pm}0.0605$ in the frequency range of 2 GHz to 3 GHz. Also the proposed method is compared with other measuring methods such as dielectric resonator and waveguide probe systems.

Design of Bent-Slotted High-Sensitivity Microstrip Patch Permittivity Sensor Antenna (구부러진 슬롯이 추가된 고감도 마이크로스트립 패치 유전율 센서 안테나 설계)

  • Yeo, Junho;Lee, Jong-Ig
    • Journal of Advanced Navigation Technology
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    • v.23 no.5
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    • pp.415-423
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    • 2019
  • In this paper, a design method for a high-sensitivity microstrip patch sensor antenna (MPSA) loaded with a bent-slot was studied for the permittivity measurement. The bent-slot similar to a single-ring complementary split ring resonator was added along a radiating edge of the patch in order to enhance the sensitivity to the permittivity. The sensitivity of the proposed MPSA was compared with that of a conventional rectangular MPSA and a thin rectangular-slotted MPSA. Three MPSAs were designed and fabricated on a 0.76-mm-thick RF-35 substrate so that the input reflection coefficient would resonate at 2.5 GHz in the absence of the superstrate under test. When five different Taconic substrates with a relative permittivity ranging from 2.17 to 10.2 were used as the superstrate under test, experiment results show that the sensitivity of the proposed MPSA, which is measured by the shift in the resonant frequency of the input reflection coefficient, is 4.1 to 6.1 times higher than that of the conventional MPSA.

Dielectric Properties on Gamma Ray Irradiated Low Density Polyethylene (방사선조사에 따른 저밀도 폴리에틸렌의 유전특성)

  • Kim, Ki-Yup;Ryu, Boo-Hyung;Kang, Seong-Hwa;Lee, Chung;Lim, Kee-Joe
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.11
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    • pp.938-942
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    • 2000
  • Radiation effects on dielectric properties of low density polyethylene(LDPE) were investigated using the various measurements of FT-IR, gel content and elongation at break. FT-IR spectra showed that polar groups were comprised in LDPE due to radiation treatment. It was also confirmed that the formation of polar groups on LDPE caused the increased dielectric properties such as permittivity and tan $\delta$. However, in this study, any evidence of decreasing permittivity was not found although the morphological change of LDPE could be identified from the increasing gel content and the decreasing elongation.

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Electrical Properties of Improved Elastomer Epoxy Resin (탄성형 에폭시의 전기적 특성평가)

  • Park, S.H.;Park, J.Y.;Lee, K.W.;Kang, S.H.;Lee, G.W.;Park, D.H.;Lim, K.J.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.53-56
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    • 2003
  • In this paper we investigated electrical properties for epoxy resin with improved mechanical property, elastomer epoxy. Investigated electrical properties are permittivity, tan $\delta$ and breakdown voltage strength(BDV). Permittivity and tan $\delta$ have dependancy on additive Quantity in general purpose epoxy resin. In particularly, those have very high values at low frequency and high temperature according to increasing component of elastomer. In case of BDV test, those materials have only a little difference due to increasing elastomer components. But in case of high quantities of elastomer, BDV has a difference. These results are represented that elastomer epoxy resin despite superior mechanical property needs many carefully thought as application electrical insulation.

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A New Inverse Scattering Technique Using the Moment Method in the Spectral Domain, II: Numerical Simulation (파수영역에서 모멘트 방법을 이용한 새로운 역산란 방법, II : 수치계산)

  • Lee, Jae-Min;Kim, Se-Yun;Ra, Jung-Woong
    • Proceedings of the KIEE Conference
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    • pp.442-445
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    • 1988
  • In this paper, the reconstruction of complex permittivity distribution on a rectangular cross section of inhomogeneous dielectric cylinders is performed by employing the spectral inverse scattering scheme. Numerical simulations provide the superresolution to the permittivity profiles nearly regardless of the measurement locations of the scattered field and the permittivity distributions on the cross section.

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A Spectral Inverse Scattering Technique by Using Moment Method with Series-Expanded Basis (급수전개된 basis를 갖는 모멘트방법에 의한 파수영역의 역산란 방법)

  • Choi, Hyun-Chul;Kim, Se-Yun;Ra, Jung-Woong
    • Proceedings of the KIEE Conference
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    • pp.446-449
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    • 1988
  • A spectral inverse technique, which was developed by applying the pulse basis moment method procedure on the direct scattering problem in the reverse sequence for the reconstruction of complex permittivity profiles inside inhomogeneous dielectric objects, is modified to be applicable to the moment method with series-expanded basis. By performing numerical simulations for various type of dielectric objects, it is demonstrated that this inverse technique provides close reconstruction of permittivity profiles. Futhermore, compared to the previous scheme of the pulse basis, the presented method is shown to reduce the computation cost, relative error of reconstructed permittivity profiles by averaging in each cell, and the ill-posedness inherent to this inverse scattering problem.

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