scholarly journals Dielectric Behavior of Low Microwave Loss Unit Cell for All Dielectric Metamaterial

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Tianhuan Luo ◽  
Bo Li ◽  
Qian Zhao ◽  
Ji Zhou
Keyword(s):  
Dielectric Constant ◽  
Microwave Frequency ◽  
Calcium Titanate ◽  
Dielectric Behavior ◽  
Unit Cell ◽  
Solid State Method ◽  
Microwave Dielectric ◽  
Unit Cells ◽  
Microwave Permittivity ◽  
Lower Loss

With a deep study of the metamaterial, its unit cells have been widely extended from metals to dielectrics. The dielectric based unit cells attract much attention because of the advantage of easy preparation, tunability, and higher frequency response, and so forth. Using the conventional solid state method, we prepared a kind of incipient ferroelectrics (calcium titanate, CaTiO3) with higher microwave permittivity and lower loss, which can be successfully used to construct metamaterials. The temperature and frequency dependence of dielectric constant are also measured under different sintering temperatures. The dielectric spectra showed a slight permittivity decrease with the increase of temperature and exhibited a loss of 0.0005, combined with a higher microwave dielectric constant of ~167 and quality factorQof 2049. Therefore, CaTiO3is a kind of versatile and potential metamaterial unit cell. The permittivity of CaTiO3at higher microwave frequency was also examined in the rectangular waveguide and we got the permittivity of 165, creating a new method to test permittivity at higher microwave frequency.

The Metallic State of Conducting Polymers: Microwave Dielectric Response and Optical Conductivity

1993 ◽  
Vol 328 ◽  
Author(s):  
A. J. Epstein ◽  
J. Joo ◽  
R. S. Kohlman ◽  
A. G. Macdiarmid ◽  
J. M. Weisinger ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Conducting Polymers ◽  
Three Dimensional ◽  
Microwave Frequency ◽  
Linear Increase ◽  
Metallic State ◽  
Microwave Dielectric ◽  
Conducting Polyaniline ◽  
New Generation ◽  
Domain Length

ABSTRACTRecent advances in processing of polyaniline and polyacetylene have resulted in a new generation of conducting polymers with higher dc conductivities. We present the temperature (T) dependent microwave frequency dielectric constant, dc conductivity, and Kramers-Kronig analysis of conducting polyaniline and polyacetylene. The low temperature dielectric constant, ε, increases with the square of the x-ray crystalline domain length for preparations of HCl protonated polyaniline. For the highest crystalline polyaniline samples, ε increases dramatically with increasing T, supporting formation of three-dimensional (3-D) coupled “mesoscopic” Metallic regions. A “metallic” negative ε is observed for d,1-camphor sulfonie acid doped polyaniline prepared in m-cresol. Optical studies show a linear increase in reflectivity below 7000 cm-1. Below 600 cm-1 the reflectance increases rapidly. Kramers-Kronig analysis of the ir-visible results are presented. Highly conducting polyaniline is shown to have two plasma frequencies, one at ∼ 1.1 eV involving all the conduction band electrons, and one at ∼0.015 eV (120 cm-1) that is suggested to arise from the most delocalized electrons. The concept of inhomogeneous disorder is introduced. The results for polyaniline are compared to those of highly doped polyacetylene which also show metallic negative ε demonstrating the intrinsic metallic nature of the new generation of conducting polymers.

Effect of Sintering Temperature on CuO Doped Barium Zinc Tantalate (BZT) Dielectric Properties

2016 ◽  
Vol 840 ◽  
pp. 8-13
Author(s):  
Hidayani Jaafar ◽  
Zainal Arifin Ahmad ◽  
Mohd Fadzil Ain
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Relative Density ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Solid State Method ◽  
Microwave Dielectric ◽  
Constant E ◽  
State Method ◽  
Tan Δ

The structure and dielectric properties of Barium Zinc Tantalate (BZT) doped by copper oxide (CuO) with a variety of values of mol% doping from 0, 0.1, 0.25, 1.0, 1.5 and 2.5 were prepared using a solid state method. The addition of CuO did not disturb the 1:2 ordering structure of the BZT ceramic. The grain size increased when the addition of doping increased. A small amount of doping elements increased the relative density. The dielectric constant (ɛr) value of the BZT significantly improved with the addition of the CuO for the specimens sintered at 1250°C and it could be explained by the increase of the relative density. The tan δ of the CuO doped with BZT ceramics is lower than pure BZT ceramics, and decreases as the CuO content increases. Meanwhile, for the percentage of bandwidth (%BW) it is shown that the best result is produced when it is doped with 0.25 mol% CuO and sintered at 1250°C. The best microwave dielectric properties obtained were ɛr=70.28, tan δ = 0.024, %BW = 7.83 which occurred for the 0.25 mol% doped CuO and when sintered at 1250°C/4 h.

scholarly journals Design, Analysis and Characterisation of Spoof Surface Plasmon Polaritons based Wideband Bandpass Filter at Microwave Frequency

2018 ◽  
Vol 68 (3) ◽  
pp. 300 ◽  
Author(s):  
Gaurav Mittal ◽  
Nagendra Prasad Pathak
Keyword(s):  
Surface Plasmon ◽  
Surface Plasmon Polaritons ◽  
Bandpass Filter ◽  
Filter Design ◽  
Microwave Frequency ◽  
Unit Cell ◽  
Unit Cells ◽  
Lc Resonator ◽  
Plasmon Polaritons ◽  
Spoof Surface Plasmon Polaritons

<p>This paper presents the wideband bandpass filter (BPF) in the microwave frequency domain. The realisation approach is based on spoof surface plasmon polaritons (SSPPs) phenomenon using plasmonic metamaterial. A novel unit cell is designed for filter design using an LC resonator concept. Then SSPPs BPF is realised using an optimised mode converter and five unit cells. This paper includes a brief design detail of the proposed novel unit cell. The passband of BPF is achieved at approximately 1.20 - 5.80 GHz, 3dB bandwidth is tentatively 4.60 GHz and the insertion loss is less than 2 dB approximately over the passband. The overall dimension of fabricated filter is (90 x 45) mm. A basic schematic of transmission line representation is also proposed to evaluate the BPF structure.</p>

Microwave dielectric properties of RETiTaO6 (RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Yb, Al, and In) ceramics

2002 ◽  
Vol 17 (10) ◽  
pp. 2561-2566 ◽  
Author(s):  
Kuzhichalil Peethambaran Surendran ◽  
Sam Solomon ◽  
Manoj Raama Varma ◽  
Pezholil Mohanan ◽  
Mailadil Thomas Sebastian
Keyword(s):  
Dielectric Constant ◽  
Ionic Radius ◽  
Microwave Dielectric Properties ◽  
Microwave Frequency ◽  
Rare Earth Ions ◽  
Ionic Radii ◽  
Low Dielectric ◽  
Microwave Dielectric ◽  
State Ceramic ◽  
High Dielectric

Microwave dielectric ceramics based on RETiTaO6 (RE = La, Cc, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Yb, Al, and In) were prepared using a conventional solid-state ceramic route. The structure and microstructure of the samples were analyzed using x-ray diffraction and scanning electron microscopy techniques. The sintered samples were characterized in the microwave frequency region. The ceramics based on Ce, Pr, Nd, Sm, Eu, Gd, Tb, and Dy, which crystallize in orthorhombic aeschynite structure, had a relatively high dielectric constant and positive τf while those based on Ho, Er, and Yb, with orthorhombic euxenite structure, had a low dielectric constant and negative τf. The RETiTaO6 ceramics had a high-quality factor. The dielectric constant and unit cell volume of the ceramics increased with an increase in ionic radius of the rare-earth ions, but density decreased with it. The value of τf increased with an increase in RE ionic radii, and a change in the sign of τf occurred when the ionic radius was between 0.90 and 0.92 Å. The results indicated that the boundary of the aeschynite to euxenite morphotropic phase change lay between DyTiTaO6 and HoTiTaO6. Low-loss ceramics like ErTiTaO6 (εr = 20.6, Quxf = 85,500), EuTiTaO6 (r = 41.3, Quxf = 59,500), and YtiTaO6 (εr = 22.1, Quxf = 51,400) are potential candidates for dielectric resonator applications.

Dielectric properties of Ba0.97Bi0.02TiO3–Ba1−xMgxSn0.02Ti0.98O3 composite ceramics

2016 ◽  
Vol 30 (29) ◽  
pp. 1650363
Author(s):  
Jing wang ◽  
Guijuan Rong ◽  
Liangbin Hao ◽  
Lan Gao ◽  
Haiyan Cheng ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Breakdown Strength ◽  
Dielectric Strength ◽  
Dielectric Behavior ◽  
Composite Ceramics ◽  
Solid State Method ◽  
Composition Formula ◽  
State Method ◽  
Mg Content

A wet solid-state method was used in this work to produce [Formula: see text]–[Formula: see text] materials. By using core-shell structure nanocubic [Formula: see text] (BMST) decorated [Formula: see text] (BBT) assemblies, a composite capacitor with improved dielectric constant and enhanced breakdown strength was successfully fabricated in contrast with the composite ferroelectric [Formula: see text]–[Formula: see text] (BBT–BST) ceramic. With increasing Mg content, the ceramic capacitors display a stronger performance in its dielectric behavior. The best dielectric properties were obtained in the composition [Formula: see text] = 0.007 with the dielectric constant above 65,000. The dielectric strength of the ceramics was measured by a withstanding voltage tester. The best dielectric strength was achieved in the composition [Formula: see text] = 0.007 with [Formula: see text] = 5.455 kV/mm.

Correlations between crystal structure and dielectric properties of high-Q materials in rock-salt structure Li2O–MgO–BO2 (B = Ti, Sn, Zr) systems at microwave frequency

RSC Advances ◽  
2016 ◽  
Vol 6 (53) ◽  
pp. 47443-47453 ◽  
Author(s):  
Haitao Wu ◽  
Eung Soo Kim
Keyword(s):  
Microwave Frequency ◽  
Dielectric Materials ◽  
Low Loss ◽  
Rock Salt Structure ◽  
Solid State Method ◽  
High Q ◽  
Microwave Dielectric ◽  
Conventional Solid State Method ◽  
Salt Structure ◽  
State Method

A series of ultra-low loss microwave dielectric materials Li2O–MgO–BO2 (B = Ti, Sn, Zr) were prepared by the conventional solid-state method.

scholarly journals Synthesis and microwave dielectric behavior of (Bi1−xPbx)NbO4 ceramics

2016 ◽  
Vol 06 (01) ◽  
pp. 1650006 ◽  
Author(s):  
S. P. Butee ◽  
K. R. Kambale ◽  
Shaishav Upadhyay ◽  
S. Bashaiah ◽  
K. C. James Raju ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Quality Factor ◽  
Dielectric Behavior ◽  
Octahedral Coordination ◽  
Microwave Dielectric Ceramics ◽  
Microwave Dielectric ◽  
Ceramic Samples ◽  
Valence States ◽  
Dielectric Ceramics ◽  
Quality Factor Q

Ceramic samples of (Bi[Formula: see text]Pbx)NbO4 ([Formula: see text], 0.025, 0.05, 0.10, 0.15, 0.20) with 0.75[Formula: see text]wt.% V2O5 addition sintered at 920[Formula: see text]C, 940[Formula: see text]C and 960[Formula: see text]C are investigated. Pb is selected as a substitute for Bi[Formula: see text] in BiNbO4 ceramics as it exists in two stable valence states of [Formula: see text]2 and [Formula: see text]4 and the average valency matches to that of Bi[Formula: see text]. The average Shannon radius (for octahedral coordination) of Pb[Formula: see text] (1.19[Formula: see text]Å) and Pb[Formula: see text](0.775[Formula: see text]Å) cations is 0.9825[Formula: see text]Å, which is similar to that of Bi[Formula: see text] ion (1.03[Formula: see text]Å). The dense ([Formula: see text]%) polycrystalline (Bi[Formula: see text]Pbx)NbO4 samples fabricated mostly reveal orthorhombic (Pnna) phase ([Formula: see text]-BiNbO4, Sp. Gp. 52) by powder XRD. Presence of satellite Pb2Nb2O7 phase, the amount of which is increasing with increase in Pb content, is also noticed. The microwave dielectric constant ([Formula: see text]) values of the niobates are found to increase from 42 to 71, whereas the quality factor (Qu.f) values are found to decrease from 5400 to 550 GHz with increasing substitution of Pb. The compositions so synthesized are important as hardly there are any microwave dielectric ceramics available with [Formula: see text].

Bayesian removal of noise for increased sensitivity in vector pattern recognition lattice imaging of interfaces

1993 ◽  
Vol 51 ◽  
pp. 994-995
Author(s):  
L. Fei ◽  
P. Fraundorf
Keyword(s):  
Pattern Recognition ◽  
Perfect Crystal ◽  
Unit Cell ◽  
Ion Milling ◽  
Beam Radiation ◽  
Major Interest ◽  
Unit Cells ◽  
Mapping Process ◽  
Increased Sensitivity ◽  
Electron Microscopes

Interface structure is of major interest in microscopy. With high resolution transmission electron microscopes (TEMs) and scanning probe microscopes, it is possible to reveal structure of interfaces in unit cells, in some cases with atomic resolution. A. Ourmazd et al. proposed quantifying such observations by using vector pattern recognition to map chemical composition changes across the interface in TEM images with unit cell resolution. The sensitivity of the mapping process, however, is limited by the repeatability of unit cell images of perfect crystal, and hence by the amount of delocalized noise, e.g. due to ion milling or beam radiation damage. Bayesian removal of noise, based on statistical inference, can be used to reduce the amount of non-periodic noise in images after acquisition. The basic principle of Bayesian phase-model background subtraction, according to our previous study, is that the optimum (rms error minimizing strategy) Fourier phases of the noise can be obtained provided the amplitudes of the noise is given, while the noise amplitude can often be estimated from the image itself.

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