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- 2018
- arbitrary coupling coefficients
- Dielectric resonator
- filtering
- coupler
- filtering balun
- dual-band
- dual-mode dielectric resonator (DR)
- Electronic Science and Technology
- Nantong University
- Sun Yat-Sen University
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Enhancement of the Electric Field and Diminishment of the Group Velocity of Light in Dielectric Multilayer Systems: A General Description
摘要： We present analytical formulae for light propagation through a multilayer of dielectric media as a function of the “total charge” and the “accumulated charge” that we propose by the transfer-matrix method. We redefine the concept of the total charge introduced by Liu et al. [J. Phys. Condens. Matter. 29, 455303 (2017)] and newly define the accumulated charge to determine the magnitude of electric field inside the multilayers analytically. In addition, we derive an analytical expression for the group velocity of light in each layer. The purpose of this work is to predict which kind of sequence would provide the strongest amplification of the electric field inside the multilayer as well as to find the sequence that gives the lowest group velocity. We find that the symmetric alternating sequence gives the best amplification of the electric field and the lowest mean group velocity compared with the other sequences.
关键词： dielectric multilayer systems,group velocity,transfer-matrix method,electric field enhancement
更新于2025-09-09 09:28:46
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Discharge characteristic and flow control experiment for pneumatic actuator of dielectric barrier discharge multistage plasma
摘要： Test and diagnosis of the characteristics of the air flow induced by the pneumatic actuation of the plasma are the important basis for the plasma flow control. In order to well understand the electrical characteristics of the pneumatic actuation of the plasma and the influence of the actuation voltage amplitude and the phase on the induced flow characteristics, the dielectric barrier discharge actuators symmetrically distributed were selected for the experimental research. The experiment result shows that the discharge form of the actuators symmetrically distributed is filamentary discharge, uniformly occurring around the high-voltage electrodes, and this is different from the discharge picture of the actuators asymmetrically distributed; when the voltage applied on the high-voltage electrode near to the actuators has the same amplitude and phase, the induced directional jet flow is vertical to the actuator surface, and the speed is at the order of meter per second; the change of the amplitude or phase of the voltage applied on the high-voltage electrode of the actuator can induce a jet flow towards the upper left or the upper right, but cannot effectively increase the induced airflow velocity.
关键词： Dielectric barrier,flow control,pneumatic actuator,discharge characteristic
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Characterization of LDPE-Metal Oxide Nanocomposites Using Thermo-Analytical and Spectroscopic Techniques
摘要： Polyethylene metal oxide nanocomposites find their application as high voltage insulation for direct current cables, to mitigate the space charge and other issues. Nano particles like SiO2, MgO, ZnO etc are used as filler materials in polyethylene matrix to achieve good electrical and mechanical properties like: space charge reduction, enhanced surface & volume resistivity and higher dielectric stress withstand capabilities. Surface modification of metal particles is usually done by treating the nanoparticles with silane to have good distribution and dispersion of metal particles. However, characterization of nanocomposite based on spectroscopic and thermo-analytical techniques is very essential to understand its long term performance and its reliability when used as insulation in HVDC extruded power cables. Different metal oxide nanoparticles such as MgO and SiO2 have been investigated as fillers in low density polyethylene. The distribution and dispersion of the nanoparticles in the LDPE is determined by SEM (Scanning Electron Microscopy). Kinetic studies were carried out by measuring enthalpy, melting temperature, percentage decomposition using simultaneous thermal analyser. Fourier Infrared spectrometer, X-ray diffractometer and dielectric spectrometer are used for characterization and dielectric response. The results are presented and discussed.
关键词： LDPE,Dielectric response,Polyethylene-metal oxide nanocomposite,HVDC cable insulation
更新于2025-09-09 09:28:46
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ANALYSIS AND DESIGN OF RECTANGULAR UNIAXIAL AND BIAXIAL ANISOTROPIC DIELECTRIC RESONATOR ANTENNAS
摘要： An anisotropic dielectric resonator antenna (ADRA) with uniaxial and biaxial permittivity tensors is characterized by using the dielectric waveguide model. An approximate formula for the Q factor of ADRA is derived. Then, it is shown that by certain conditions a wideband ADRA can be designed. Samples of simulation results are shown to demonstrate the capabilities of the proposed anisotropic technique for enhancing the bandwidth of ADRA. The proposed antenna is simulated by two full wave packages, Ansoft HFSS and CST Microwave Studio, and a good agreement is observed among the results.
关键词： anisotropic dielectric resonator antenna,simulation,dielectric waveguide model,permittivity tensors,CST Microwave Studio,wideband,biaxial,Ansoft HFSS,Q factor,uniaxial
更新于2025-09-04 15:30:14
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Preparation of Ultra-low Temperature Sintering Ceramics with Ultralow Dielectric Loss in Na <sub/>2</sub> O-WO <sub/>3</sub> Binary System
摘要： A series of new microwave dielectric ceramics with ultralow dielectric loss in Na2O-WO3 binary system were prepared by the modified solid-state reaction method at ultra-low sintering temperatures. Three stable phases, namely Na2WO4, Na2W2O7 and Na2W4O13, were formed in the system. Their stability in the air, phase composition, compatibility with metal electrodes, microstructures and microwave dielectric properties were investigated. In this binary system, the cubic structure Na2WO4 ceramic sintered at 565?C exhibited the best microwave dielectric properties with a permittivity of 5.6, a Q × f value of 124 200 GHz and a temperature coefficient of -63 ppm/?C at a frequency of 13.1 GHz. The Na2WO4 ceramic is chemically compatible with Ag and Al electrodes. Besides, the Na2WO4 ceramic has favorable stability in the air. Due to the excellent dielectric properties and favorable stability in the air, the Na2WO4 ceramic is a great candidate for LTCC devices.
关键词： Ultra-low dielectric loss,Microwave dielectric ceramics,Ultra-low firing
更新于2025-09-04 15:30:14
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[IEEE 2018 48th European Microwave Conference (EuMC) - Madrid, Spain (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - Extraction of Relative Permittivity from Measured Reflection Coefficient of Dielectric Materials in the Frequency Range 207 – 247 GHz
摘要： This work describes the use of millimetre wave technology to extract the dielectric constants of different types of dielectric materials. The extraction of the dielectric materials is based on measurements (i.e., monostatic measurements) of the reflection coefficient for various dielectric materials. The measurements are done by utilizing a frequency modulated continuous wave radar with a dielectric lens antenna. The investigated materials are broadly utilized as a part of our everyday life. The fundamental dielectric materials outcomes are done accompanying materials: Polytetrafluoroethylene (PTFE), mainly Teflon, nylon, and. The measurements are done in the frequency range from 207 GHz to 247 GHz.
关键词： reflection coefficient,material characteristics,corner reflector,millimeter wave length,dielectric materials,permittivity,measurement,lens antenna
更新于2025-09-04 15:30:14
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[IEEE 2018 48th European Microwave Conference (EuMC) - Madrid, Spain (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - Pulse-Distortion Analysis for Millimeter-Wave Time-Domain Material Identification
摘要： Analyzing the frequency dependent dielectric properties can be used to identify and distinguish materials in biomedical instruments. In the millimeter-wave range, the dielectric properties of biological tissues are mainly determined by their water content. For instance, it has been shown, that cancer cells have a lower water content than healthy skin cells, resulting in a significant dielectric contrast between them. In this work, we analyze the pulse distortion observed in measurements of the millimeter-wave reflection of water and porcine skin. We propose to use the distortion caused by the frequency dependent reflection coefficient at the interface of a material as a feature for identification. Using a simplified model for the reflection coefficient of the material under test, we simulate the distortion caused by the frequency dispersion. In simulation as well as in measurement, we observe different startup transients depending on the dispersion properties of a material under test. The startup behavior can therefore be used as feature, to directly identify dispersive materials in the time domain.
关键词： Dielectric,Time-domain analysis,Electromagnetic,Biomedical,Measurements,Characterization,Measurement,Pulse,Wavelet Generator,Reflection
更新于2025-09-04 15:30:14
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Effect of crosslinks, entanglements, and chain extensibilities on dynamic electromechanical instability of dielectric elastomers
摘要： Dynamic electromechanical instability (EMI) can affect the actuation performance of dielectric elastomers (DEs). This letter develops a theoretical framework to investigate the dynamic EMI of DEs with diverse crosslinks, entanglements, and chain extensibilities under a step voltage and equal biaxial pre-stresses. Based on the work-energy principle combining the EMI condition, the dynamic instability parameters at transition state between the stable and instable states are determined. At the small pre-stress, weak crosslinks or strong entanglements contribute to achieving a high actuation stretch ratio. When the pre-stress further increases, the DE with strong entanglements is prone to the dynamic EMI, and the variation in the dynamic instability actuation stretch ratio with the level of crosslinks is non-monotonic, which forms a peak. Moreover, as the level of chain extensibilities reduces, the dynamic instability actuation stretch ratio increases, and the enhancement effect can be significant at the large pre-stress. These results can help optimize the dynamic DE to obtain a stable oscillation without the dynamic EMI or utilize dynamic EMI to achieve a dramatic deformation.
关键词： Entanglements,Chain extensibilities,Dielectric elastomers,Crosslinks,Dynamic electromechanical instability
更新于2025-09-04 15:30:14
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Physical Properties of Pure and Nano Ag Doped Liquid Crystalline Compounds Containing 1,3,4-Oxadizole Unit
摘要： Dielectric properties and other physical properties such as electrical conductivity (AC) and relaxation time or activation energy have been studied for two systems pure LC [V]6,6, [V]7,6, [V]8,6, [V]6,7, [V]7,7 and [V]8,7 and their doped with silver nanoparticles. The results show the increasing in real dielectric permittivity ? with increasing length terminal chain. So the real dielectric permittivity increasing with raising temperature. To compare between the values of (400) Hz and (4000) Hz we observe these values at the low frequency are larger than that in high frequency. Generally, one can see that the doping of Ag nano particles effectively reduced the permittivity of the LC materials with its large electric dipole moment. The electrical conductivity σ value for pure LC samples in general increases with increasing temperature. So we observed increasing of electrical conductivity values at high frequency. The time scale is discussed in terms of the Arrhenius plot. Generally, with increasing the temperature the time period that spends by molecules at the transition state will increase. The activation energy Ea values show the increase in the activation energy to the doped systems.
关键词： Dielectric permittivity,Doped liquid crystals,Liquid crystals,Relaxation time,Electrical conductivity,Activation energy,Silver nanoparticles
更新于2025-09-04 15:30:14
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Independently controllable dual-band filter using single quad-mode silver-loaded dielectric resonator
摘要： This article proposes a novel bandpass filter with two controllable passbands using a single quad-mode silver-loaded dielectric resonator (DR). The silver plane is inserted in the middle of the cubic DR and two degenerate pairs are used to build the two passbands. Because of the distinct E-field distributions, the silver plane has significant effect on the degenerate pair (TEx112 and TEy112), whereas another one (TEx111 and TEy111) remains unchanged. With the aid of the silver plane, both center frequencies and bandwidths of the two bands can be controlled independently. To verify the proposed idea, a prototype dual-band BPF is designed and fabricated. Good agreement between simulated and measured results can be observed.
关键词： dual-band bandpass filter (BPF),dielectric resonator (DR),quad-mode,independently controllable
更新于2025-09-04 15:30:14