Showing papers on "Relative permittivity published in 1977"
TL;DR: In this article, a model of soil composed of a multiphase mixture of solid particles, water, and air voids is proposed from which the complex permittivity, or dielectric constant and conductivity, is calculated.
Abstract: A model of soil composed of a multiphase mixture of solid particles, water, and air voids is proposed from which the complex permittivity, or dielectric constant and conductivity, is calculated. It is based on the Hanai/Bruggelman/Wagner theory of mixtures and considers the ionic conducting water as partly dispersed and partly the dispersing medium, an important distinction with this theory. The permittivity as a function of frequency and water content is predicted. The increase in dielectric constant with water volume fraction does not differ greatly with soil type in the high-frequency limit and is approximated by a normal curve specified by the theory. A normal curve and the marked increase in dielectric constant at lower frequencies has been observed experimentally. It is concluded that this semidisperse theory of the dielectric permittivity is successful in describing the behavior of soils containing moisture in the high-frequency range (1 MHz-1 GHz). Approximations to the more detailed theory and a series-parallel RC equivalent circuit are given.
113 citations
TL;DR: In this paper, the capacitance and conductance of bovine cortical bone have been measured at body temperature as functions of frequency, time, and humidity, and a direct-coupled low-frequency bridge containing active circuits was used to study the response below 50 Hz.
Abstract: Measurements of the capacitance and conductance of bovine cortical bone have been performed at body temperature as functions of frequency, time, and humidity. A direct‐coupled low‐frequency bridge containing active circuits was used to study the response below 50 Hz. Results are expressed in terms of permittivity, dielectric loss tangent, and both frequency‐ and time‐dependent electric moduli. The permittivity was found to be extremely sensitive to frequency and humidity; maximum permittivity observed exceeded 105, while the maximum loss tangent was greater than unity. Anisotropy was observed; both the permittivity and the loss tangent were greater if the electric field was parallel to the bone axis.
57 citations
TL;DR: In this article, a method of determining the dielectric properties of materials using the polarisation force exerted by a special (isomotive) field configuration is described, which allows for the permittivity and in some instances the conductivity, to be determined as a function of frequency.
Abstract: A method of determining the dielectric properties of materials using the polarisation force exerted by a special (isomotive) field configuration is described. The technique allows for the permittivity, and in some instances the conductivity, to be determined as a function of frequency. An important feature is that electrodes are not required to be attached to the test sample, which may be of arbitrary shape.
55 citations
TL;DR: In this paper, a time domain method of total reflected signals on a dielectric sample in a coaxial line is proposed to determine the complex constant of propagation of the medium to be studied and, consequently, its complex permittivity.
Abstract: The authors propose a time domain method of total reflected signals on a dielectric sample in a coaxial line. This method enables the determination of the complex constant of propagation of the medium to be studied and, consequently, its complex permittivity. Contrary to other similar methods employed up to now, this method needs neither iterative calculation nor nomograms. The validity of this multiple reflection approach is illustrated by the study of several primary alcohols. The values of the permittivities and relaxation frequencies thus acquired are in good agreement with those obtained elsewhere.
45 citations
TL;DR: In this paper, a waveguide system is described which enables the complex permittivity of medium and high-loss liquids to be measured at 70 GHz, and the design and constructional details of two waveguide cells are given together with a brief description of the methods of analyzing the data.
Abstract: A waveguide system is described which enables the complex permittivity of medium- and high-loss liquids to be measured at 70 GHz. The design and constructional details of two waveguide cells are given together with a brief description of the methods of analysing the data. Results of measurements on various liquids are included.
39 citations
TL;DR: In this article, the authors used the transmission dispersive Fourier transform, spectrometry (DFTS) for the measurements of both real and imaginary parts of the complex relative permittivity of low-loss materials at millimeter and submillimeter wavelengths.
Abstract: Transmission dispersive Fourier transform, spectrometry (DFTS) has been used for the measurements of both real and imaginary parts of the complex relative permittivity of low-loss materials at millimeter and submillimeter wavelengths. The materials investigated include cis and trans decalin and polypropylene.
32 citations
TL;DR: In this article, the wavelength of a guided wave in nonsymmetrical coplanar line on substrate with relative permittivity constant in range from 2 to 110 was measured at frequencies from 2.5 to 10 GHz.
Abstract: The wavelength of a guided wave in nonsymmetrical coplanar line on substrate with relative permittivity constant in range from 2 to 110 was measured at frequencies from 2.5 to 10 GHz. A comparison with theoretical relation calculated from simplified TEM model was done.
23 citations
TL;DR: In this paper, the authors deal with the modes of the dielectric post resonator when epsilon/sub r/ is large and give simple approximate expressions for the resonant frequencies of lower order modes.
Abstract: This short paper deals with the modes of the dielectric post resonator when epsilon/sub r/ is large. The normalized frequency F/sub 0/ = (pi D/lambda/sub 0/) /spl radic/ as a function of D/L is discussed. The simple approximate expressions for the resonant frequencies of the lower order modes are given. The properties of the TE/sub 011/, mode are discussed in detail from the point of view of its application to the measurement of the complex permittivity of microwave dielectrics. Curves and expressions for fast and simple determination of the maximum measurement errors are given.
22 citations
TL;DR: In this paper, local field effects are calculated in the R.P.A. approximation from two extreme points of view: the first consists of an analytical inversion of the dielectric matrix in reciprocal space and the second treats these effects in real space in a tight-binding limit, thus leading to a Lorentz-Lorenz formula.
Abstract: 2014 Local field effects are calculated in the R.P.A. approximation from two extreme points of view. The first consists of an analytical inversion of the dielectric matrix in reciprocal space. If confirms the results of recent numerical calculations, that local field effects tend to reduce the dielectric constant. The second treats these effects in real space in a tight-binding limit, thus leading to a Lorentz-Lorenz formula. In this limit it is shown, contrary to the usual belief, that local-field effects also tend to reduce 03B5. A detailed numerical analysis is performed in the case of purely covalent semiconductors, showing that the local field correction increases in the sequence C, Si, Ge, Sn. LE JOURNAL DE PHYSIQUE , TOME 38, MAI 1977. Classification Physics Abstracts 8.720 8.812
18 citations
TL;DR: In this article, a cylindrical cavity which is split into equal parts is designed to operate in the TE011 mode, and yarn is placed across the midplane of the cavity and a textile sample is placed in the cavity on a low-loss dielectric sheet in annular form.
Abstract: Modified cavity perturbation methods for permittivity measurements of yarn and textile are described. A cylindrical cavity which is split into equal parts is designed to operate in the TE011 mode. The dielectric yarn is placed across the midplane of the cavity and a textile sample is placed in the cavity on a low-loss dielectric sheet in annular form. The shift in the resonant frequency and change in Q-factor are measured and the complex permittivity is calculated.
13 citations
TL;DR: In this paper, the field scattered by a homogeneous isotropic dielectric particle illuminated by a low-frequency plane electromagnetic wave is expressed in terms of a single polarizability tensor which is a function of only the geometry of the particle and a material parameter r representing either the relative permittivity or permeability of the dielectrics.
Abstract: The field scattered by a homogeneous isotropic dielectric particle illuminated by a low-frequency plane electromagnetic wave is expressed in terms of a single polarizability tensor which is a function of only the geometry of the particle and a material parameter r representing either the relative permittivity or permeability of the dielectric. The mathemati- cal formulation is specialized to the case of a rectangular parallelepiped and numerical techniques are developed for computing the tensor elements. Specific data are presented for the tensor elements of rectangular parallelepipeds having square cross sections and are compared to the results obtained for spheroids and right circular cylinders of similar dimensions.
TL;DR: In this article, the position-independent principal axes for the relative permittivity tensor in inhomogeneous anisotropic media are obtained and the results derived from the general equation are discussed.
Abstract: Finite‐difference equations in inhomogeneous anisotropic media, characterized by the position‐independent principal axes for the relative permittivity tensor are obtained. Discrete inhomogeneities are discussed and results derived from the general equation. Finally, two examples are given to illustrate the application of the theory.
TL;DR: In this paper, the effective relative permittivity of coplanar waveguides is measured as a function of frequency in the frequency range from 3-12 GHz and compared with the computed values.
Abstract: The dependence of the effective relative permittivity of coplanar waveguides is measured as a function of frequency in the frequency range from 3-12 GHz and is compared with the computed values.
TL;DR: In this paper, the effect of a DC electric field on the Curie point was investigated under hydrostatic pressure, and the results showed that the P-E double hysteresis loop obeys the Cole-Cole dispersion law and the real part of the permittivity in the antiferroelectric phase increases with increasing DC electric fields.
Abstract: Some dielectric properties of Cu(HCOO)24H2O under hydrostatic pressure such as the P-E double hysteresis loop, the frequency and pressure dependence of the complex permittivity and the effect of a DC electric field on the Curie point were investigated under hydrostatic pressure. The results are as follows: (i) the P-E double hysteresis loop was observed under hydrostatic pressure; (ii) the permittivity obeys the Cole-Cole dispersion law; (iii) the real part of the permittivity in the antiferroelectric phase increases with increasing DC electric field; (iv) the Curie point shifts towards lower temperatures with increasing DC field.
TL;DR: In this article, the authors measured the permittivity and dielectric loss in benzene for five different concentrations varying from 002 to 010 wt fraction at three different microwave frequencies, viz 331, 983, and 2690 GHz at 35 °C.
Abstract: The permittivity e′ and dielectric loss e″ of octanoyl, undecanoyl, and lauroyl chlorides have been measured in benzene for five different concentrations varying from 002 to 010 wt fraction at three different microwave frequencies, viz 331, 983, and 2690 GHz at 35 °C The static permittivity e0 at 100 kHz and the high frequency limiting permittivity e∞ have also been measured at the same temperature The permittivity and dielectric loss at different frequencies have been plotted against concentration and their slopes have been used to draw normalised complex plane plots between (a′–a∞)/(a0–a∞) and a″/(a0–a∞) for these compounds Such plots show a skewed arc dielectric behaviour The values of distribution parameter β, characteristic relaxation time τ0, average relaxation time τav, and dipole moment μ have been reported for the first time The relaxation mechanism in these three molecules has been explained on the basis of multiple relaxation processes
TL;DR: In this paper, a two coupler method for measurement of dielectric properties of materials, at microwave frequencies, is described. But this method is only applicable for measurements of dieelastic properties of aerosols and gases.
Abstract: This paper describes two coupler method for measurement of dielectric properties of materials, at microwave frequencies. Two waveguide sections, fed from a common source, are coupling power into a waveguide filled with dielectric. The phase and attenuation constants are computed from the values of phase and attenuation adjustment required for cancellation of the signal in the dielectric filled waveguide. The two coupler method is particularly applicable for measurements of dielectric properties of aerosols and gases.
TL;DR: The dielectrophoretic force on single yeast cells in water has been measured by the method of balancing it against the force of gravity and the force expression for the electrode geometry of parallel wires is derived and related to the electrical properties of the cell and its surroundings through the parameter K, the excess relative permittivity.
Abstract: The dielectrophoretic force on single yeast cells in water has been measured by the method of balancing it against the force of gravity The force expression for the electrode geometry of parallel wires is derived and related to the electrical properties of the cell and its surroundings through the parameter K, the excess relative permittivity A detailed analysis is given of the two alternate experimental approaches that can be taken using the balance technique Experimental values of K are determined for various conditions and compared with those predicted from a theoretical model of a yeast cell
01 Oct 1977
TL;DR: In this paper, the experimental results of hertrian spectrum analysis of phosphate as function of moisture content have been used to build a moisture rate controller in the microwave frequency range, and the results of this study has been used for building a moisture control system.
Abstract: This paper deals with the experimental results of hertrian spectrum analysis of phosphate as function of moisture content. A study has been developed in the microwaves frequencies range the results of this study has been used to built a moisture rate controller.
01 Oct 1977
TL;DR: In this paper, the authors propose a method in which the substrate is in sandwich between two similar dielectric resonators, which permits to determine the permittivity of a small area (few mm2) of the substrate, by comparing the measured and calculated resonant frequencies of the studied structure.
Abstract: Several methods have been described to measure the permittivity of dielectric substrate, and all used the complete area of the sample and so give an average value of this parameter. But in the realization of microwave integrated circuits it is important to know dielectric parameters of the substrate at the point where the component is located. For this local characterization, we propose a method in which the substrate is in sandwich between two similar dielectric resonators. This non destructive method permits to determine the permittivity of a small area (few mm2) of the substrate, by comparing the measured and calculated resonant frequencies of the studied structure.
TL;DR: Fujimoto et al. as mentioned in this paper investigated the effect of the d.c. electric biasing field on the Curie point under hydrostatic pressure and showed that the dielectric relaxation obeys the Cole-Cole's dispersion law.
Abstract: Some dielectric properties of Cu(HCOO)24H2O such as the frequency dependence of the complex permittivity, D-E double hysteresis loops and the effect of the d.c. electric biasing field on the Curie point were investigated under hydrostatic pressure. The results are: (1) The dielectric relaxation obeys the Cole-Cole's dispersion law. (2) The D-E double hysteresis loops observed under hydrostatic pressure are as predicted analytically in a previous paper (S. Fujimoto et al.: Japan. J. appl. Phys. 15 (1976) 595). (3) The real part of the permittivity in the antiferroelectric phase increases with increasing d.c. electric biasing field. (4) The Curie point shifts toward the lower temperature side with increasing d.c. electric biasing field.
01 Jun 1977
01 Jun 1977
TL;DR: In this article, it was shown that there is a low-frequency contribution to the dielectric permittivity of BaTiO3 crystals due to the existence of some equilibrium positions in the unit cell for Ti or other ions.
Abstract: It is shown that there is the low-frequency contribution to the dielectric permittivity e s 33 of the clamped single domain BaTiO3 crystals due to existence of some equilibrium positions in the unit cell for Ti or other ions. The internal field of the spontaneous polarization makes these positions inequivalent and the ions occupying the higher potential minima have the anomalously low frequencies of the thermal vibrations and the large relaxation polarizabilities. The low-frequency contribution to e s 33 increases with the temperature and explains the discrepancy between the values of e s 33 measured and calculated from the Lyddane-Sachs-Teller relation.1