ELECTRIC POLARIZATION MEASUREMENTS ON YELLOW BIRCH

1964 ◽  
Vol 42 (6) ◽  
pp. 1270-1281 ◽  
Author(s):  
A. J. Nanassy
Keyword(s):  
Electric Field ◽  
Grain Orientation ◽  
Electric Polarization ◽  
Wide Frequency Range ◽  
Betula Alleghaniensis ◽  
Frequency Range ◽  
Yellow Birch ◽  
General Variation ◽  
Polarization Spectra ◽  
Frequency Temperature

Electric polarization spectra of oven-dry yellow birch (Betula alleghaniensis Britt.) were measured over the range of frequencies from 50 kc/s to 50 Mc/s and temperatures from 20° to 100 °C. These observations, which provide only a section of the total dispersion and relaxation absorption spectra of the material, give information on the general variation of the dispersion curve with frequency, temperature, and grain orientation to the electric field, and indicate that the total spectra spread over a wide frequency range, probably from 0 c/s to a few Gc/s and include several absorption peaks and dispersion curves.

A reduced formulation for modelling time-harmonic electromagnetic field in the media with thin highly conductive inclusions

2018 ◽  
Author(s):  
Э.П. Шурина ◽  
Д.В. Добролюбова ◽  
Е.И. Штанько
Keyword(s):  
Electric Field ◽  
Variational Formulation ◽  
Computational Cost ◽  
Surface Current ◽  
Wide Frequency Range ◽  
Geometrical Shape ◽  
Frequency Range ◽  
Surface Current Density ◽  
Time Harmonic ◽  
The Media

При решении задач электромагнетизма в широком частотном диапазоне в областях с тонкими пластинами, оболочками и экранами численными методами возникает проблема резкого роста сеточной дискретизации вблизи внутренних структур с разномасштабными габаритными размерами. В работе предложена модификация вариационной постановки векторного метода конечных элементов, основанная на снижении размерности модели в окрестности тонких включений, которая позволяет преодолеть эту проблему за счет специфического учета таких структур на уровне вариационной постановки. Так как редуцирование модели обычно приводит к появлению ограничений на область ее применимости, выполнено исследование диапазона допустимых частот, контрастности электрофизических характеристик матрицы и включений, геометрических особенностей внутренней структуры, для которых предложенная модель позволяет получить корректные с точки зрения физики результаты. Purpose. In this paper, we propose a reduced variational formulation for the Helmholtz equation for the electric field, in which thin highly conductive objects are approximated by surfaces with the equivalent surface current density. We conduct a study aimed at defining the range of application for the reduced variational formulation, focusing on highly contrasting thin objects of various geometrical shape and arrangement in a wide frequency range. Methodology. The modelling is performed on unstructured tetrahedral meshes. Since the reduced variational formulation treats thin highly conductive objects as surfaces, no volume mesh is constructed inside of them.We compare the results obtained by the vector FEM using the proposed variational formulation with the results obtained using standard formulation. Findings. Due to the fact that the proposed variational formulation does not require volume meshing of the thin objects, its computational cost is significantly lower. However, the reduced formulation yields correct results in a restricted frequency range. It also imposes some limitations on the minimal contrast and maximal thickness of the thin highly conductive objects. Originality/value. The proposed reduced variational formulation can be applied to simulate the time-harmonic electric field in the media with thin highly conductive inclusions of either regular or chaotic arrangement, as well as thin shielding plates or casings of various geometrical forms.

Improved Dielectric Properties of Heterostructured Ba0.5Sr0.5TiO3 Thin Film Composites for Microwave Dielectric Devices

2002 ◽  
Vol 748 ◽  
Author(s):  
M. Jain ◽  
S. B. Majumder ◽  
R. S. Katiyar ◽  
A. S. Bhalla ◽  
D. C. Agrawal ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Electric Field ◽  
Figure Of Merit ◽  
Phase Shifter ◽  
Wide Frequency Range ◽  
Thin Layers ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
Microwave Dielectric ◽  
Dielectric Devices

ABSTRACTIn the present work we have deposited MgO and Ba0.5Sr0.5TiO3 (BST50) thin layers in different sequences to make MgO:BST50 hetero-structured thin films. These films were characterized by X-ray diffraction and found to be highly (100) textured. The figure of merit {(C0-Cv)/(C0.tand)} of the hetero-structured films was found to be higher as compared to pure BST50 films measured at 1 MHz frequency with electric field of 25.3 kV/cm. These films were used to make eight element coupled micro-strip phase shifter and characterized in a frequency range of 13–15 GHz. The high frequency figure of merit (k factor, defined as the ratio of degree of phase shift per dB loss) measured at around 14 GHz with electric field of 333 kV/cm has been markedly improved (around 64.28 °/dB for hetero-structured film as compared to 24.65 °/dB for pure film). Improvement in dielectric properties in a wide frequency range in the MgO:BST are believed to be due to the higher densification of the hetero-structured films.

scholarly journals Radiating Slot in the Coaxial Cable Shield: Measurement Based Characterization

2015 ◽  
Vol 11 (3) ◽  
pp. 136
Author(s):  
Antonio Šarolić ◽  
Zlatko Živković ◽  
Damir Senić ◽  
Niko Ištuk
Keyword(s):  
Experimental Study ◽  
Electric Field ◽  
Communication Systems ◽  
Wide Frequency Range ◽  
Coaxial Cable ◽  
Wireless Communication Systems ◽  
Frequency Range ◽  
Radiation Characteristics ◽  
Orthogonal Components ◽  
The Common

The paper presents the comprehensive experimental study of radiation characteristics of a single slot in a coaxial cable shield. The slot was realized in four different embodiments, which varied by slot orientation and length. Three orthogonal polarizations of radiated electric field were analyzed along the axis perpendicular to cable, broadside to the slot, in a broadband frequency range (80-1000 MHz). The analysis was based on thorough measurements of the coupling loss, which is the common parameter for the leaky cable characterization. The obtained results showed that the electric field component longitudinal to the cable axis considerably dominates over other two orthogonal components, for all four slot types. Doubling the length of the slot caused a ca. 20 dB increase of the radiated field. Different slot orientations, having the same length in the cross-section projection, yielded approximately equal field strengths. The results of this experimental study clearly and visibly demonstrate the radiating slot field dependence on polarization and slot geometry in a wide frequency range. Thus they are useful for planning of wireless communication systems based on radiating cables, as well as for understanding polarization related issues in such systems.

Spontaneous electric polarization and electric field gradient in hybrid improper ferroelectrics: insights and correlations

2021 ◽  
Author(s):  
Samuel Silva dos Santos ◽  
Michel L. Marcondes ◽  
Ivan P. Miranda ◽  
Pedro Rocha-Rodrigues ◽  
Lucy Vitória Credidio Assali ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Ab Initio ◽  
Field Gradient ◽  
Electric Polarization ◽  
Double Perovskites

An ab-initio study for several hybrid improper ferroelectric (HIF) materials in the Ruddlesden-Popper phases and double perovskites structures is here presented. The focus is on the correlation between the electric...

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