• Title, Summary, Keyword: Permittivity

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Complex Permittivity of Sand at Low Frequency (저주파수 영역에서 측정된 사질토의 유전특성)

  • Oh Myoung Hak;Kim Yong Sung;Park Jun Boum;Yoon Hyun Suk
    • Journal of the Korean Geotechnical Society
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    • v.21 no.2
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    • pp.93-103
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    • 2005
  • This study was performed to identify the presence of measurement distortions such as electrode polarization and to investigate the influence of soil water content on complex permittivity at low frequency. In low frequency measurement using two-terminal electrode system, electrode polarization effect was observed at frequencies less than approximately 100 HBz. The analysis for real permittivity should be performed at frequencies above 100 kHz in order to exclude electrode polarization effect in the analysis of real permittivity at low frequency measurements. For a given soil, both of real and effective imaginary permittivity of wet soil increased continuously with volumetric water content. This is evidenced by the facts that the real permittivity is proportional to the number of dipole moments per unit volume and effective imaginary permittivity is effected by the conduction due to water. However, proportional relation between real permittivity and volumetric water content is valid at upper MHz frequencies.

Influence of laminating and sintering condition on permittivity and shrinkage during LTCC process (LTCC 공정 중 적층 및 소결이 유전율과 회로 형상에 미치는 영향)

  • Jeong, M.S.;Hwang, S.H.;Chung, H.W.;Rhim, H.S.;Oh, S.I.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.67-70
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    • 2007
  • LTCC (Low Temperature Co-fired Ceramic) has been emerged as a promising technology in packaging industry. In this technology the lamination and the sintering process are very important because they change the permittivity of ceramics and the dimension of metal pattern which have influences on electric property. In this paper we studied on influence of the permittivity and the dimension change by lamination pressure and sintering temperature of LTCC process. As a results, permittivity increase along with increasing of lamination pressure and sintering temperature.

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Measurement of Electromagnetic Properties of Concrete for Nondestructive Testing (비파괴 시험을 위한 콘크리트의 전자기적 특성의 측정)

  • 임홍철;정성훈
    • Journal of the Korea Concrete Institute
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    • v.12 no.3
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    • pp.115-123
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    • 2000
  • Characterizing the electromagnetic properties of concrete is essential to the enhancement of accuracy and reliability in nondestructive testing of concrete structures using electromagnetic techniques. To establish a data base for the properties of concrete, a measurement technique has been developed and a set of data has been obtained for the frequency range of 1~6 GHz. As moisture content is one of major contributing factors to determine permittivity of dielectric material, moisture content is varied during the measurement. An application of a measurement system which consists of open-ended coaxial probe and automatic network analyzer to concrete and mortar specimens is studied. For this, calibration techniques, size of specimens, and number of measurements necessary to obtain reliable data are investigated. From the measured data, it is shown that moisture content plays an important role to determine the permittivity of specimens. As the moisture content increases. The permittivity of specimens show tendency to approach the permittivity of water.

Simple Technique for Measurement of Complex Permittivity and Detection of Small Permittivity Change Using Partially Open Cavity

  • Park, Sangbok;Chung, Young-Seek;Cheon, Changyul
    • Journal of Electrical Engineering and Technology
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    • v.9 no.1
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    • pp.268-272
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    • 2014
  • This letter presents a measurement methodology of the complex permittivity of liquid using a partially open cavity in narrow band. The partially open cavity (POC) can measure dielectric small changes caused by the temperature variation of the liquid inside the cavity as well. Using the resonance frequency and unloaded quality factor of the proposed POC, the complex permittivity is evaluated. The apertures on the walls of the cavity are designed to circulate the liquid inside to outside of the POC and located at the corner area of the cavity to minimize the disturbance of field distribution at the dominant mode. The results measured by the proposed POC were compared with those by the conventional open-ended probe and Cole-Cole equation. The POC showed better performance in measuring small dielectric constant changes than the open-ended probe.

Extended Mixing Rule to Complex Permittivity

  • Wakino, Ki-Kuo
    • Journal of the Korean Ceramic Society
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    • v.40 no.4
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    • pp.371-374
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    • 2003
  • Various types of equation for mixing rule on permittivity of mixture have been proposed, but none of these is not perfect because of the inconsistency between the actual geometrical configuration and the basic model for calculation. Serial model and parallel model are lower and upper extremes of mixing manner, the apparent permittivity of any other type of mixture stay between these two extreme states. For the random mixture of the stumpy fine particles, customarily the logarithmic mixing rule has been applied. But, the logarithmic mixing rule does not give the proper value of permittivity in low or high mixing rate of constituent. The author proposed the new mixing rule that gives better consistency with measured value in whole mixing range compared to the logarithmic rule. In this paper, a desirable refinement on the equation proposed in the previous paper is made to adapt to thr configuration image of actual compound and then the equation has been expanded to the complex permittivity to apply the mixing rule on the dissipative materials cases.

Non-Resonant Waveguide Technique for Measurement of Microwave Complex Permittivity of Ferroelectrics and Related Materials

  • Jeong, Moongi;Kim, Beomjin;Poplavko, Yuriy;Kazmirenko Victor;Prokopenko Yuriy;Baik, Sunggi
    • Journal of the Korean Ceramic Society
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    • v.42 no.7
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    • pp.449-454
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    • 2005
  • A waveguide method is developed to study the materials with relatively large dielectric constants at microwave range. Basically, the method is similar to the previous waveguide methods represented by short-circuit line and transmission/reflection measurement methods. However, the complex permittivity is not determined by the shift in resonance frequencies, but by numerical analysis of measured scattering parameters. In order to enhance microwave penetration into the specimen with relatively large permittivity, a dielectric plate with lower permittivity is employed for impedance matching. The influences of air gap between the specimen and waveguide wall are evaluated, and the corresponding errors are estimated. The propagation of higher order modes is also considered. Experimental results for several reference ceramics are presented.

Influence of Laminating and Sintering Condition on Permittivity and Shrinkage During LTCC Process (LTCC 공정 중 적층 및 소결이 유전율과 회로 형상에 미치는 영향)

  • Jeong, M.S.;Hwang, S.H.;Chung, H.W.;Rhim, S.H.;Oh, S.I.
    • Transactions of Materials Processing
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    • v.16 no.5
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    • pp.396-400
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    • 2007
  • LTCC(Low Temperature Co-fired Ceramic) which offers a good performance to produce multilayer structures with electronic circuits and components has emerged as an attractive technology in the electronic packaging industry. In LTCC module fabrication process, the lamination and the sintering are very important processes and affect the electrical characteristics of the final products because the processes change the permittivity of ceramics and the dimension of the circuit patterns which have influences on electronic properties. This paper discusses the influence of lamination pressure and sintering temperature on the permittivity and the dimensional change of LTCC products. In the present investigation, it is shown that the permittivity increases along with increasing of the lamination pressure and the sintering temperature.

Permittivity Adjustment and Impedance Matching of Ferrite Composite Microwave Absorber (복합 Ferrite 전파흡수체의 유전율 제어 및 임피던스 정합)

  • 최경구;조성백;권경일;김성수;김재묵
    • Journal of the Korean Ceramic Society
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    • v.29 no.4
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    • pp.293-297
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    • 1992
  • A proper combination of complex permeability and permittivity is necessary to produce the zero-reflection microwave absorber with an impedance matching. Increasing of dielectric permittivity and development of an impedance matching was investigated in ferrite-rubber composite specimens by addition of conducting materials. Graphite powder of high dielectric constant was added to the composite specimens to increase the permittivity. The precise estimation of graphite content to produce the matched-wave-impedance absorber at a given frequency can be made by using the numerically derived solution map of impedance matching. It was suggested that permittivity adjustment is an effective technique to obtained the microwave absorber with both good absorbing properties and small thickness as well.

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Microwave Absorbing Characteristic Improvement by Permittivity Control of Ferrite Composite Microwave Absorber (유전율제어에 의한 복합 Ferrite 전파흡수체의 성능향상)

  • 신재영;권형주;오재희
    • Journal of the Korean Ceramic Society
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    • v.31 no.4
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    • pp.415-419
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    • 1994
  • The material constants(the complex permeability and permittivity) of ferrite composite determine its microwave absorbing characteristics. Therefore, in order to improve the microwave absorbing characteristics, it is necessary to control the material constants of the ferrite composite. In this study, the method of improving microwave absorbing characteristics by control of permittivity of ferrite composite which has not satisfying matching condition in C-X band (4 GHz~12.4 GHz) was investigated. It was possible to control the permittivity by adjusting graphite loading ratio in the ferrite composite microwave absorber. It was also concluded that the control of permittivity of ferrite composite is effective method to improve the microwave absorbing characteristics.

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Microwave Rectangular Waveguide Measurement of the Engine Oil Dielectric Constant (초고주파 구형도파로를 이용한 엔진 오일의 유전율 측정)

  • Kim, Ki-Hoon;Kim, Young-Ju
    • Tribology and Lubricants
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    • v.27 no.3
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    • pp.156-161
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    • 2011
  • The rectangular waveguide technique can be used to measure the complex permittivity of dielectric material of various thickness and cross section. This paper presents the analysis system of engine oil permittivity at which deterioration of engine oil is measured at the X-band(8-12.5 GHz). The middle of the rectangular waveguide has engine oil case and is connected with VNA(Vector Network Analyzer) for the measurement of the transmission$(S_{21})$ and reflection$(S_11)$ and then the permittivity is extracted. The deterioration of engine oil is proved by the comparison with both the extracted data and reference data. As the additional research, This paper suggest that an accurate permittivity is considered by not only the wave guide length but the air gap between oil case and the waveguide.