• 제목/요약/키워드: microwave dielectric

검색결과 734건 처리시간 0.028초

Numerical Method for Computing the Resonant Frequencies and Q-factor in Microwave Dielectric Resonator

  • Kim, Nam-young;Yoo, Hojoon
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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    • pp.245-248
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    • 1997
  • The dielectric resonators(DRs) with dielectric properties are widely used in microwave integrated circuit(MICs) and monolithic microwave integrated circuits(MMICS). The variational method as numerical simulation scheme would be applied to calculate the resonant frequencies(fr) and Q-factors of microwave dielectric resonators. The dielectric resonator with a cylindrical “puck” structure of high dielectric material is modeled in this simulation. The parameters, such as the diameter, the height, and the dielectric constant of dielectric resonator, would determine the resonant frequency and the Q-factor. The relationship between these parameters would effect each other to evaluate the approximate resonant frequency. This simulation method by the variational formula is very effective to calculate fr, and Q-factor. in high frequency microwave dielectric resonator The error rate of the simulation results and the measured results would be considered to design the microwave dielectric resonators.

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유전가열물질을 코팅한 활성탄소섬유의 휘발성 유기화합물 흡착 및 마이크로파 인가에 의한 탈착 연구 (A Study on Adsorption of Volatile Organic Compound by Activated Carbon Fiber Coated with Dielectric Heating Element and Desorption by Applying Microwave)

  • 김상국;장예림
    • 한국대기환경학회지
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    • 제25권2호
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    • pp.122-132
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    • 2009
  • Adsorption of toluene by activated carbon fiber (ACF) coated with dielectric heating element and desorption by applying microwave were investigated. In order to prepare adsorbent so that VOC can be desorbed by microwave heating, fine dielectric heating element with nano size was coated on the surface of the ACF using hybrid binder. Eight adsorbents (ACF-DHE, Activated Carbon Fiber coated with Dielectric Heating Element) were prepared with different amount of dielectric heating element, kinds of hybrid binder, and solvent. In order to investigate adsorption characteristics, BET surface area, pore volume, and average pore size were measured for each adsorbent including ACF. Breakthrough experiments with toluene concentration, flow rate, bed length using fixed bed reactor were performed to investigate adsorbality of adsorbent, and results were compared with that of the ACF. Desorption reactor was constructed with modified microwave oven to investigate heating effect on ACF-DHE by applying microwave power. Each adsorbent saturated with toluene were put into desorption reactor. Composition of desorbed gas generated by applying controlled microwave power to reactor was measured. Up to now, hot air desorption method has been used. Experimental results showed that desorption method with new adsorbent prepared by coating dielectric heating element on ACF can be used for industrial application.

불순물 첨가에 따른 $(1-x)MgTiO_3-xCaTiO_3$ 세라믹스의 마이크로웨이브 유전특성변화 (Effect of Dopants on the Microwave Dielectric Properties of $(1-x)MgTiO_3-xCaTiO_3$ Ceramics)

  • 우동찬;이희영;한주환;김태홍;최태구
    • 한국세라믹학회지
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    • 제34권8호
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    • pp.843-853
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    • 1997
  • The effect of dopant on microwave dielectric properties of (1-x)MgTiO3-xCaTiO3 ceramics, known to be used as microwave dielectric resonators for global positioning system and personal communication system, has been analyzed in terms of variations in defect concentrations and microstructural features with its addition. The addition of dopants was revealed to result in a significant change in the microstructure as well as defect concentration of the ceramics. For instance, the quality factor is proportional to sintered density of the ceramics by inversely proportional to grain size as well as vacancy concentration. Accordingly, it is believed that the dopant effect on the microwave dielectric properties should be separately analyzed with either microstructural change or the change in vacancy concentration.

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Evaluation of Microwave Dielectric Properties of MgO-TiO2 System by Dielectric Mixing Rules

  • Kim, Eung-Soo;Seo, Seock-No
    • 한국세라믹학회지
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    • 제47권2호
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    • pp.163-168
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    • 2010
  • Effects of compositions on the microwave dielectric properties of the MgO-$TiO_2$ system were investigated as a function of the molar ratio of MgO to $TiO_2$ ($0.9{\leq}MgO/TiO_2\;(x){\leq}1.2$). With the compositional changes, secondary phases of $MgTi_2O_5$ and $Mg_2TiO_4$ were also detected along with $MgTiO_3$. Microwave dielectric properties of the specimens were dependent on the types of phases developed in the sintered specimens. A single phase of $MgTiO_3$ showed a dielectric constant (K) of 18.2, a quality factor (Qf) of 198,000 GHz, and a temperature coefficient of resonant frequency (TCF) of $-51\;ppm/^{\circ}C$. However, the dielectric properties of the specimens with a secondary phase of $MgTi_2O_5$ (K=19.9, Qf=48,000 GHz) and/or $Mg_2TiO_4$ (K=15.6, Qf=56,000 GHz) were worsened. Dependence of the microwave dielectric properties on the secondary phase of the MgO-$TiO_2$ system was also discussed in terms of dielectric mixing rules.

$La(Zn_{1/2}Ti_{1/2})O_3$의 합성 및 고주파 유전특성 (Synthesis and Microwave Dielectric Properties of $La(Zn_{1/2}Ti_{1/2})O_3$)

  • 서명기;조서용;홍국선;박순자
    • 한국세라믹학회지
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    • 제33권9호
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    • pp.1019-1023
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    • 1996
  • The dielectric properties at microwave frequencies of B site complex perovskite La(Zn1/2Ti1/2)O3 which has +3 ion in A site were investigated. maximum Q*F value of the specimens was 59000 dielectric constant 34, temperature coefficient of resonant frequency -52 ppm/$^{\circ}C$. XRD pattern of the sintered specimen shows (111) ssuperlattice reflection which indicates Zn and Ti cation ordering.

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마이크로파에서 얇은 유전체의 유전상수 및 유전손실의 측정방법에 대한 연구 (A Dielectric Measurement Technique of Thin Samples at Microwave Frequencies)

  • Kim, Jin-Hun
    • 대한전자공학회논문지
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    • 제25권12호
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    • pp.1582-1585
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    • 1988
  • A cavity perturbation technique is employed to determine the dielectric property of thin samples. Substrates in microwave integrated circuits are fabricated in sheet form and are expected to have a dielectric constant less than 10 and a dielectric loss better than 10**-3. This research aimed to determine both dielectric constant and dielectric loss with good accuracy. The tecynique makes use of thin circular disk samples placed in a right circular cylindrical cavity. The accuracy of measurements is within \ulcorner% for dielectric constnat and 3x10**-4 for dielectric loss.

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Cavity Perturbation Method를 이용한 마이크로파 주파수대의 고온 유전특성 측정 연구 (Measurement of High Temperature Dielectric Property at Microwave Frequency Using Cavity Perturbation Method)

  • 김동은;정진호;이성민;김형태
    • 한국분말재료학회지
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    • 제13권6호
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    • pp.455-461
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    • 2006
  • High temperature dielectric constants of the various ceramic materials have been measured using cavity perturbation method. The measurements were applied to refractory, traditional and fine ceramic powder compacts from room temperature to $1200^{\circ}C$. Calibration constant in the equation suggested by Hutcheon et al., was determined from the dielectric constants of reference specimen (teflon and alumina) at room temperature. From these results, informations on the refectory materials were obtained for the microwave kiln design and understanding of the microwave heating effects of ceramics have been improved.

고주파 기판용 PTFE 복합체 형성 압력에 따른 유전 특성 (Dielectric Characteristics of Polytetrafluoroethylene-based Composites for Microwave Substrates with Formation Pressure)

  • 최홍제;전명표;조용수;조학래
    • 한국전기전자재료학회논문지
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    • 제26권6호
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    • pp.429-433
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    • 2013
  • PTFE composites for use of microwave substrate were fabricated by impregnation and heat treatment fabrication with glass fabric. This study shows dielectric properties such as dielectric constant and loss can be controlled by thickness of PTFE composite with change of pressure condition in heating press process. The dielectric constant of the PTFE composites has decreasing tendency as given higher pressure condition. The dielectric loss has similar result too. Especially, the case of the dielectric loss was affected by the condition of pressure at heating press and had the best performance under 3 MPa. In order to see the reason why thickness conditions make different, their microstructures were also observed.

Effects of Crystal Structure on Microwave Dielectric Properties of Ceramics

  • Kim, Eung-Soo;Jeon, Chang-Jun;Kim, Sung-Joo;Kim, Su-Jung
    • 한국세라믹학회지
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    • 제45권5호
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    • pp.251-255
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    • 2008
  • Microwave dielectric properties of $MgTiO_3,\;MgWO_4,\;MgNb_2O_6$, and $MgTa_2O_6$ were investigated based on the structural characteristics. The dielectric constant (K) was dependent on the dielectric polarizabilities of the specimens, and the deviation of the observed dielectric polarizabilities (${\alpha}_{obs.}$) from the theoretical dielectric polarizabilities (${\alpha}_{theo.}$) were decreased with increasing of Mg-site bond valence. Quality factors (Qf) were affected by the sharing type of $MgO_6$ and $BO_6$ octahedra. Temperature coefficient of resonant frequency (TCF) was decreased with increasing of average octahedral distortion.