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Plasma and Plasmonics || 6 Spoof Surface Plasmons (SSP)
摘要： In the previous chapter, we studied the properties of surface plasmons on a planar metal-dielectric interface and found that for these waves to exist, the permittivity of the dielectric and metal must be of opposite signs. This condition is satisfied at frequencies slightly below the metal plasma frequency, since in this frequency range, the permittivity of the metal is given by ?/?0 = 1 ? ω2p/ω2. These surface plasmon waves are characterized by three quantities: β, k1, k2. β is the propagation constant along the interface, k1 is the decay constant in the dielectric medium and k2 is the decay constant in the metallic region. These quantities depend on the permittivities and frequency through these relations (Eqs. (5.24) and (5.26)).
关键词： metal-dielectric interface,permittivity,Spoof Surface Plasmons,plasma frequency,SSP,surface plasmons
更新于2025-09-16 10:30:52
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Research on epoxy-based nanocomposites with high energy density and charge-discharge efficiency filled with Ti0 <sub/>2</sub> nanofibers
摘要： Capacitor films with high energy density are critical to energy storage. However, the energy density of state-of-the-art commercial capacitor films are limited by their low dielectric permittivity. In this study, epoxy-based nanocomposite films are prepared by filling with TiO2 nanofibers. Results show that nanocomposite films have larger discharge energy density because of the significant increase in dielectric permittivity, which caused by the additional interface polarization and space charge polarization. And a superior charge-discharge efficiency is achieved in the composite films at the same time due to the low dielectric loss. In addition, the composites also keep a high breakdown strength because of the dispersion of the nanofibers. The discharge energy density of 5.19 J/cm3 with the efficiency of 80% is achieved at 470 MV/m in the nanocomposites containing 2wt% nanofibers. The excellent energy density and charge-discharge efficiency of epoxy-based nanocomposites offer a promising opportunity for future researches and industrial application.
关键词： dielectric permittivity,energy density,epoxy-based nanocomposites,charge-discharge efficiency,TiO2 nanofibers
更新于2025-09-16 10:30:52
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[IEEE 2019 XXIVth International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Lviv, Ukraine (2019.9.12-2019.9.14)] 2019 XXIVth International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Waveguide Millimeter Wave Measurement Cell with Minimum Reflection Coefficient for Complex Permittivity Determination of Bioactive Liquids
摘要： An original waveguide millimeter wave measurement cell for complex permittivity determination of bioactive high-loss liquids was studied numerically and experimentally. This measurement cell consisted of round metal waveguide, Teflon inserted and glass capillary with liquid under test inside. The main features of the measurement cell are as follows. Waveguide connections (matching elements) to input and output waveguides have minimum reflection coefficient. The capillary with the high loss liquids under test located not in the electromagnetic field maximum as usual, but at an angle to the wave propagation along the waveguide cell. The advantages of such capillary location were discussed in the paper. This waveguide millimeter wave measurement cell was compared with the symmetrical waveguide millimeter wave measurement cell for complex permittivity determination.
关键词： millimeter waves,reflection coefficient,Microwave resonator,complex permittivity,bioactive liquids,frequency spectrum,waveguide
更新于2025-09-16 10:30:52
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Finite element modeling of effective permittivity in nanoporous epoxy composite filled with hollow nanosilica
摘要： The relative permittivity of nanoporous epoxy composites (NPCs) filled with hollow nanosilica is lower than that of unfilled epoxy resin. The low permittivity is considered to arise from the existence of cavity volume, but the effects of nanosilica particle shape, particle size distribution and agglomeration are not clear. In this study, the relative permittivity of an NPC filled with hollow nanosilica is modeled by using finite-element method including the above-mentioned factors. The proposed model successfully reproduces the experimentally-obtained low permittivity of NPCs. The effect of cavities is significant, while particle corner shape, particle size distribution or particle agglomeration is not dominant.
关键词： epoxy,permittivity,nanoporous composite,hollow nanosilica
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 31st International Conference on Microelectronics (MIEL) - Nis, Serbia (2019.9.16-2019.9.18)] 2019 IEEE 31st International Conference on Microelectronics (MIEL) - Reviewing MXenes for Plasmonic Applications: Beyond Graphene
摘要： MXenes are an emerging class of two-dimensional (2D) materials consisting of carbides, nitrides or carbonitrides of early transition metals. Due to the metallic type of conductivity of MXenes and their 2D structure, they are an ideal candidate to replace the conductive materials currently used in plasmonics, especially graphene. However, the use of MXenes for plasmonics and metamaterials is in its embryonal stage and practically all relevant publications appeared in the last few years. In this contribution we first consider some methods of MXenes fabrication. We continue by analyzing the optical and electronic properties of MXenes of interest for plasmonics (especially spectral dispersion of complex relative dielectric permittivity). We proceed by reviewing some reported applications of MXenes in plasmonics, including among others conventionally designed chemical and biological sensors based on surface plasmon resonance (SPR), metasurface-based optical absorbers and MXene-based nanoantennas, as well as some possible applications in nonlinear optics. In addition to that, we propose some novel uses of MXenes in plasmonics, including chemical and biological nanosensors, superabsorbers with a variable widths of the nanoholes, etc. It is our opinion that the applications of MXenes in plasmonics introduced until now are only scratching the surface of a vast bulk of potential practical devices, structures and effects.
关键词： absorbers,sensors,dielectric permittivity,MXenes,plasmonics,2D materials
更新于2025-09-12 10:27:22
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Error Tolerant Method of Dielectric Permittivity Determination Using a TE?? Mode in a Circular Waveguide at the W-Band
摘要： We propose a new method for the precise measurement of dielectric permittivity of ceramics and polymers at millimeter-wave frequencies that employs the TE01 mode of a circular waveguide. At higher frequencies, accurately measuring the dielectric permittivity of materials becomes extremely challenging by using the fundamental TE10 mode of a rectangular waveguide. As the frequency increases, the dimensions of the dielectric sample that has to be fit into the waveguide become very small. Therefore, small fabrication imperfections that produce air gaps between the sample and the wall of the waveguide result in significant errors during measurements. In contrast, the TE01 mode of the circular waveguide that does not have an electric field at the surface of the waveguide is insensitive to small imperfections during fabrication. We measured the dielectric permittivity in small samples of alumina (Al2O3), magnesium calcium titanate (MCT) ceramics, and Teflon placed in a circular waveguide. The results showed that the method was very robust with respect to manufacturing imperfections: when dimensions of the alumina and Teflon samples varied by as much as 10% and 20%, the differences in the computed dielectric permittivity of the alumina were only 1.26% and 3.06%, respectively, and those of Teflon were 1.98% and 2.12%. In addition, when the high-dielectric permittivity material MCT samples were deformed by 5% and 10%, the differences were just 0.04% and 0.14% each, respectively. We believe that this new proposed method is also applicable to even higher frequencies in the THz regime and at a very high relative dielectric permittivity of larger than 10.
关键词： millimeter waves,Ceramic materials,measurement,resonant-based method,dielectric permittivity,waveguide
更新于2025-09-12 10:27:22
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Debye Frequency-extended Waveguide Permittivity Extraction for High Complex Permittivity Materials. Concrete Setting Process Characterization
摘要： A waveguide with central frequency 868 MHz is used in transmission/re?ection operation regime to accurately measure the behaviour of the complex permittivity of high complex permittivity granular materials and it has been frequency-extended up to 3 GHz using the Debye ?tted relaxation model. It is shown that for highly granular high permittivity materials a waveguide based transmission/re?ection technique is necessary to reduce the uncertainty of the extracted permittivity values. The technique is ?rst described and validated with isopropyl alcohol and then applied to the characterization of cement based materials. This paper provides accurate data on the evolution of the complex permittivity of concrete and mortar from the moment of pouring until air dried condition is achieved.
关键词： loss tangent,Debye,RFID,MSE,loss factor,waveguide,concrete setting process,relative permittivity
更新于2025-09-12 10:27:22
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[IEEE 2019 49th European Microwave Conference (EuMC) - Paris, France (2019.10.1-2019.10.3)] 2019 49th European Microwave Conference (EuMC) - Electrically Controlled Tunable Broadband Interferometric Dielectric Spectroscopy: Groundwork for Single Cell Analysis
摘要： An electrically controlled tunable interference based microwave sensor is demonstrated to perform time domain detection of single particles and measure complex permittivity of cell culture mediums within the broadband range of 12-18 GHz. Following set up is required to construct deep destructive interference nulls. Quadrature hybrid (QH), voltage controlled phase shifter and attenuator are utilized for each of the two branches. These comprise a reference branch and a branch containing the material-under-test (MUT). Coplanar waveguide (CPW) design was used as the microwave sensing structure and microfluidic wells were manufactured with polydimethylsiloxane (PDMS) to contain MUT, reference and calibration materials. The capability of detecting a single particle (diameter of 6-6.4um) is reported compared to simulations. Cell culture mediums measurements of Luria Agar (LA) and Luria Broth (LB) medium over the above-mentioned bandwidth were performed to demonstrate the operation processes and lay the groundwork for future research.
关键词： complex dielectric permittivity,microwave interferometry,microfluidics,spectroscopy,dielectric sensor
更新于2025-09-12 10:27:22
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AIP Conference Proceedings [AIP Publishing APPLIED PHYSICS OF CONDENSED MATTER (APCOM 2019) - Strbske Pleso, Slovak Republic (19–21 June 2019)] APPLIED PHYSICS OF CONDENSED MATTER (APCOM 2019) - Cured epoxy resin dielectric characterization based on accurate waveguide technique
摘要： Complex permittivity of a substrate plays an important role in designing a compact and robust antenna. Thus, measuring complex permittivity must be done carefully in order to achieve accurate and reliable result. Waveguide is a widely used technique to determine complex permittivity of a dielectric material. In this paper the permittivity of cured epoxy resin is determine using waveguide technique, within the G-band frequency range. It determines the complex permittivity by analyzing only the measured transmission coefficient of the material and easily noise affected reflection coefficient is not used. Sample is only partially loaded in the waveguide to avoid the resonance during measurement. Therefore, results obtained are accurate and reliable. Also, the estimated real part of complex permittivity is in a good agreement with available data from other work.
关键词： complex permittivity,epoxy resin,G-band frequency,waveguide technique,dielectric material
更新于2025-09-12 10:27:22
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Effect of Laser Ablation on Microwave Attenuation Properties of Diamond Films
摘要： Thermal conductivity is required for developing high-power microwave technology. Diamond has the highest thermal conductivity in nature. In this study, a diamond ?lm was synthesized by microwave plasma chemical deposition, and then long and short conductive graphite ?bers were introduced to the diamond ?lms by laser ablation. The permittivity of the samples in the K-band was measured using the transmission/re?ection method. The permittivity of diamond ?lms with short graphite ?bers increased. The increase in real part of permittivity can be attributed to electron polarization, and the increase in the imaginary part can be ascribed to both polarization and electrical conductivity. The diamond ?lms with long graphite ?bers exhibited a highly pronounced anisotropy for microwave. The calculation of microwave absorption shows that re?ection loss values exceeding ?10 dB can be obtained in the frequency range of 21.3–23.5 GHz when the graphite ?ber length is 0.7 mm and the sample thickness is 2.5 mm. Therefore, diamond ?lms can be developed into a microwave attenuation material with extremely high thermal conductivity.
关键词： high thermal conductivity,laser ablation,diamond ?lms,microwave attenuation,permittivity
更新于2025-09-12 10:27:22