Microwave Electromagnetic Characteristics of a Microcoiled Carbon Fibers/paraffin Wax Composite in Ku Band

2002 ◽  
Vol 17 (5) ◽  
pp. 1232-1236 ◽  
Author(s):  
Jin-Hong Du ◽  
Chao Sun ◽  
Shuo Bai ◽  
Ge Su ◽  
Zhe Ying ◽  
...  
Keyword(s):  
Carbon Fibers ◽  
Loss Tangent ◽  
Relative Permittivity ◽  
Magnetic Loss ◽  
Attenuation Factor ◽  
Paraffin Wax ◽  
The Real ◽  
Tan Δ ◽  
Factor Α ◽  
Ku Band

The complex relative permittivity ∈γ and permeability μγ of microcoiled carbon fibers (MCCFs) imbedded in paraffin wax were measured at Ku band frequencies (12.4–18 GHz). Both the real and imaginary parts of the complex relative permittivity of the MCCFs/paraffin wax composite decreased with increase of the frequency. The real part of the complex relative permeability of the composite increases with increase of the frequency, and the imaginary part is nonzero and nearly constant over the measured frequency range. The dielectric loss tangent (tan δ∈), the magnetic loss tangent (tan δm), and amplitude attenuation factor (α) were determined as well. On the basis of the experimental results, the MCCFs/paraffin wax composite is mainly a kind of dielectric lossy material with small magnetic loss and diamagnetism in the Ku band.

AC CONDUCTIVITY AND DIELECTRIC PROPERTIES OF MANGANESE DOPED LAYERED Na1.89Li0.10K0.01Ti3O7 CERAMICS

2013 ◽  
Vol 28 (01) ◽  
pp. 1350200
Author(s):  
SHRIPAL SHARMA ◽  
RAKESH SINGH ◽  
GEETIKA
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
Chemical Synthesis ◽  
Loss Tangent ◽  
Relative Permittivity ◽  
Ac Electrical Conductivity ◽  
Conduction Mechanisms ◽  
Tan Δ ◽  
Electron Clouds ◽  
Derivatives Of

Manganese doped derivatives of polycrystalline Na 1.89 Li 0.10 K 0.01 Ti 3 O 7 bearing 0.01, 0.05 and 1.0 molar % of manganese have been prepared by chemical synthesis. The results of ac electrical conductivity studies in form of log (σT) versus 1000/T plots are reported in the frequency and temperature range of 10 kHz–1 MHz and 350–775 K, respectively. The corresponding plots have been divided into five temperature regions, I, II, III, IV and V. The various conduction mechanisms in different regions have been discussed. The nature of conductivity has been explained by proposing a model about the obtained conductivity σ(ω) which is the sum of three terms arising from three different mechanisms. Moreover, various Na–K–Li–O–Ti–O linkages in Na 2-x-y Li x K y Ti 3 O 7 materials may result special forms of electron clouds. Experimental results of the loss tangent ( tan δ) and relative permittivity (εr) versus temperature at different frequencies have been described. The results of tan δ and εr versus frequency plots at different temperature have also been given for these doped derivatives.

THE DIELECTRIC CONSTANT OF BROMINE AT MICROWAVE FREQUENCIES

1967 ◽  
Vol 45 (7) ◽  
pp. 2349-2354 ◽  
Author(s):  
I. R. Dagg ◽  
G. E. Reesor ◽  
R. P. Doble
Keyword(s):  
Dielectric Constant ◽  
Loss Tangent ◽  
Optical Range ◽  
Frequency Range ◽  
Improved Method ◽  
Microwave Frequencies ◽  
The Real ◽  
Liquid Bromine ◽  
Tan Δ

Measured values of the real part of the dielectric constant, ε′, and the loss tangent, tan δ, of liquid bromine at 20 °C in the frequency range 8.2–18 GHz are presented. The results for tan δ were obtained by a previously described technique; the results for ε′ were obtained by an improved method herein described. A suggested mechanism for absorption is discussed and the results related to static values and values in the optical range.

Mechanical and Microwave Dielectric Properties of Csf/Si3N4 Composites

2007 ◽  
Vol 546-549 ◽  
pp. 1661-1664
Author(s):  
Xiao Yan Wang ◽  
Fa Luo ◽  
Dong Mei Zhu ◽  
Wan Cheng Zhou ◽  
Hong Huan Wu
Keyword(s):  
Carbon Fibers ◽  
Microwave Dielectric Properties ◽  
Xrd Analysis ◽  
Network Analyzer ◽  
Hot Press ◽  
Frequency Range ◽  
The Real ◽  
Microwave Dielectric ◽  
Hot Press Sintering ◽  
Sintering Method

Csf/Si3N4 composites were prepared by hot-press sintering method using α-Si3N4 power, short chopping carbon-fiber and sintering additives. XRD analysis showed that the α-Si3N4 was almost completely transferred into β-Si3N4. The SEM micrographs of fractured surfaces showed that special network developed by rod-like β- Si3N4 grains. The flexure strength of 590±10MPa, and fracture toughness of 7.94±0.1MPa·m1/2 were achieved for the samples incorporated with 0.5wt% the carbon fibers .The microwave dielectric property of Csf/Si3N4 composites was measured at a frequency range of 8.2~18GHz by E8362B PNA series network analyzer. The real part (ε ′ ) of the permittivity of the Csf/Si3N4 composites increases from 10 to 58 with the rise of the content of carbon fibers in the composites, as well as the imaginary part increases from 0.03 to 98 at frequency of 9.375GHz. A strong frequency dependence of the real part was observed both in X and Ku bands.

Improvement of electric insulation in dielectric layered perovskite nickelate films via fluorination

2022 ◽  
Author(s):  
Takuma Nishimura ◽  
Tsukasa Katayama ◽  
Shishin Mo ◽  
Akira Chikamatsu ◽  
Tetsuya Hasegawa
Keyword(s):  
Dielectric Permittivity ◽  
Loss Tangent ◽  
Layered Perovskite ◽  
Electric Insulation ◽  
Tan Δ

Layered perovskite nickelates have recently emerged as materials with colossal dielectric permittivity. However, they exhibit relatively high values of loss tangent (tan δ) owing to insufficient electric insulation; thus, lowering...

Split-Post and Split-Cylinder Resonator Techniques: A Comparison of Complex Permittivity Measurement of Dielectric Substrates

2009 ◽  
Vol 6 (2) ◽  
pp. 97-100 ◽  
Author(s):  
Michael D. Janezic ◽  
Jerzy Krupka
Keyword(s):  
Loss Tangent ◽  
Relative Permittivity ◽  
Test Methods ◽  
Standard Test ◽  
Fused Silica ◽  
Dielectric Substrates ◽  
Permittivity Measurement ◽  
Level Of Agreement ◽  
Ltcc Substrate ◽  
Complex Permittivity Measurement

We provide an overview of two nondestructive techniques, the split-post and split-cylinder resonator, which are under consideration as standard test methods for measuring the relative permittivity and loss tangent of bare low-temperature cofired ceramic (LTCC) substrates over the frequency range of 1–30 GHz. The capabilities and limitations of the split-post and split-cylinder resonator are outlined, and the level of agreement between the two techniques is examined through comparison of the relative permittivity and loss tangent measurements of a fused silica and an LTCC substrate.

Efficient Electromagnetic Wave Absorption of Porous CoO–Co@RGO Composites with Optimized Impedance Matching Derived from Metal-Organic Frameworks

NANO ◽  
2020 ◽  
Vol 15 (08) ◽  
pp. 2050104
Author(s):  
Ying Meng ◽  
Shibin Lu ◽  
Yaodong Wu ◽  
Zhenfa Zi ◽  
Yuan Ma ◽  
...  
Keyword(s):  
Magnetic Loss ◽  
Impedance Matching ◽  
Metal Organic Frameworks ◽  
Filler Loading ◽  
Absorption Bandwidth ◽  
Conduction Loss ◽  
High Dielectric Loss ◽  
Metal Organic ◽  
High Dielectric ◽  
Ku Band

In this study, we have successfully synthesized porous CoO–Co@RGO composites using GO and Co-based metal-organic frameworks (MOFs) as precursors. Due to particular structures and advantageous characteristics, the synthesized porous CoO–Co@RGO composites exhibit outstanding electromagnetic (EM) wave absorbing properties with a filler loading of 10[Formula: see text]wt.% in wax matrix. The maximum reflection loss (RL) of the prepared porous CoO–Co@RGO was [Formula: see text][Formula: see text]dB with 2.1[Formula: see text]mm thickness, and the effective absorption bandwidth as wide as 6.24[Formula: see text]GHz (11.76–18[Formula: see text]GHz), which covers the full Ku-band. Remarkably, the achieved all values of[Formula: see text]RL were under [Formula: see text][Formula: see text]dB with 1.0–5.0[Formula: see text]mm thickness, the corresponding to bandwidth range can be tuned to 13.84[Formula: see text]GHz (4.16–18[Formula: see text]GHz). The superior absorbing performance is attributed to suitable magnetic loss, high dielectric loss and large attenuation mainly caused by conduction loss and polarization relaxation.

Study on Dielectric and Magnetic Properties of MWCNTs/Polyester Composites

2015 ◽  
Vol 815 ◽  
pp. 188-192
Author(s):  
Y.S. Lee ◽  
F. Malek ◽  
E.M. Cheng ◽  
Wei Wen Liu ◽  
Kok Yeow You ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Magnetic Properties ◽  
Dielectric Properties ◽  
Rectangular Waveguide ◽  
The Real ◽  
Multi Walled Carbon Nanotubes ◽  
Polyester Composites ◽  
Walled Carbon Nanotubes ◽  
Ku Band ◽  
Dielectric Conductivity

This paper is to study the dielectric properties, magnetic properties, and dielectric conductivity of Multi-walled carbon nanotubes (MWCNTs) and polyester (PE) composites. The composites with different amount of MWCNTs (5-15%) have been studied in the Ku-Band range (12.4-18 GHz). The rectangular waveguide (WR-62) was used to measure the dielectric properties and magnetic properties of the samples. The results show the dielectric properties and conductivity of MWCNTs/PE composites is increasing with the MWCNTs filler increases. The real part of dielectric properties values increase from 5.5 to 26.6 with increasing the MWCNTs loading from 5 % to 15 %. The increasing of MWCNTs filler in the MWCNTs/PE composites does not effects on magnetic properties, the real part and imaginary part of magnetic properties are approximate to 1 and 0. The highest conductivity of 15 % MWCNTs loading is reach to 11.02 (S/m) at 18 GHz. Keywords: composites, dielectric properties, magnetic properties, conductivity

ELECTRODE MATERIAL EFFECT ON CAPACITANCE AND LOSS TANGENT OF THE ORGANIC ZnPc SEMICONDUCTING THIN FILMS

2007 ◽  
Vol 21 (01) ◽  
pp. 55-67 ◽  
Author(s):  
A. O. ABU-HILAL ◽  
R. D. GOULD ◽  
M. I. ABU-TAHA ◽  
A. M. SALEH
Keyword(s):  
Thin Films ◽  
Loss Tangent ◽  
Strong Dependence ◽  
Electrical Contact ◽  
Equivalent Circuit Model ◽  
Zinc Phthalocyanine ◽  
Strong Temperature Dependence ◽  
Low Frequencies ◽  
Tan Δ ◽  
Semiconducting Thin Films

The capacitance and loss tangent of thermally evaporated zinc phthalocyanine, ZnPc , semiconducting thin films were measured in the temperature range of 180–430 K and frequency between 0.1 and 20 kHz. Aluminum and gold electrical contact electrodes were employed to sandwich ZnPc films. For both electrode types, the capacitance and loss tangent showed strong dependence on both temperature and frequency. Such dependence is related to the relevant temperature and frequency range under consideration. The capacitance has strong temperature dependence for T>240 K and frequency below 3 kHz, while it becomes a constant at higher frequencies and all temperatures. The loss tangent dependence on temperature is more evident at low frequencies and a minimum or an indication of a minimum was observed in tan δ versus f curves. Loss tangent variation with temperature was not monotonic for all frequencies. An anomaly (maximum) in tan δ was observed approximately between 300 and 360 K. This maximum was attributed to the presence of oxygen molecules in the sample and their subsequent exhaustion as the temperature is increased. The behavior of capacitance and loss tangent (for both Al and Au -electrodes) may be explained qualitatively and successfully in terms of an equivalent circuit model.

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