Showing papers on "Relative permittivity published in 1982"
TL;DR: A summary of fitted parameters for the tissue data is presented, which can be used to reconstruct the original data values, and the contribution of cells and organelles to the dielectric permittivity of one tissue is estimated.
Abstract: Dielectric permittivity and conductivity measurements are reported from various soft excised mammalian non-tumour tissues, at frequencies between 0.1 and 100 MHz, and at room and body temperatures. The data over this wide frequency range can be well represented by a Cole-Cole equation for either the complex conductivity or complex permittivity. A summary of fitted parameters for the tissue data is presented, which can be used to reconstruct the original data values. The data are compared to older data that are still frequently quoted. Finally, the contribution of cells and organelles to the dielectric permittivity of one tissue is estimated, to help elucidate the mechanisms that are responsible for the observed dielectric data.
253 citations
TL;DR: In this paper, the temperature dependence of the lattice constant in Na0.5Bi 0.5TiO3 single crystal was studied by means of X-ray diffraction and two structural phase transitions were found in the temperature range 293-920 K.
Abstract: The temperature dependence of the lattice constant in Na0.5Bi0.5TiO3 single crystal was studied by means of X-ray diffraction. Two structural phase transitions were found in the temperature range 293-920 K: the cubic-to-tetragonal at 793 ± 5 K and the tetragonal-to-rhombohedral at 533 ± 5 K. The dielectric permittivity was measured and a considerable dispersion was observed. The shift of the dielectric permittivity maximums are linear in coordinates 1/T = F(In f).
246 citations
TL;DR: In this article, the design of a microstrip antenna covered with a dielectric layer is presented, where the effect of loading on the resonant frequency of the antenna is considered.
Abstract: The design of a microstrip antenna covered with a dielectric layer is presented. Due to loading, the resonant frequency of the antenna changes. The absolute value of the change increases with the operating frequency, the relative permittivity (except plasma), and the thickness of the dielectric layer. This change may cause degradation in performance due to the inherent narrow bandwidth of microstrip antennas if the effect of loading is not considered in the design. The curves presented here may be used to design microstrip antennas that may be subjected to icing or a plasma environment or coated with protective layers. Numerical and experimental results for the fractional change in the resonant frequency are round to be in good agreement.
231 citations
TL;DR: In this paper, solid solution ceramics in the Ba(Zn1/3Nb2/3)O3(BZN) and SZN system have been studied with a view to finding materials for use as dielectric resonators at microwave frequency.
Abstract: Solid solution ceramics in the Ba(Zn1/3Nb2/3)O3(BZN)–Sr(Zn1/3Nb2/3)O3 (SZN) system have been studied with a view to finding materials for use as dielectric resonators at microwave frequency. The relative dielectric constant and the unloaded Q at 10 GHz are respectively 41 and 5400 for BZN, and 40 and 2000 for SZN. The temperature coefficient of the resonant frequency is estimated as 30 ppm/°C for BZN and -38 ppm/°C for SZN. The dielectric constant of 0.3 BZN–0.7 SZN ceramic is nearly independent of temperature, which gives a very small estimated temperature coefficient of the resonant frequency of -5 ppm/°C.
134 citations
24 May 1982
TL;DR: In this paper, the effect of substrate thickness and relative permittivity on the radiation properties of printed circuit dipoles (PCD's) is investigated for a polytetrafluorethylene (PTFE) glass random fiber substrate.
Abstract: The effect of substrate thickness and relative permittivity on the radiation properties of printed circuit dipoles (PCD's) is investigated. A trade-off between substrate thickness and resonant input resistance, bandwidth, and radiation efficiency is presented for a polytetrafluorethylene (PTFE) glass random fiber substrate. It is found that for a fixed substrate thickness h , the resonant length and directivity decrease with increasing relative dielectric constant \epsilon_{r} . The E - and H -plane normalized power pattern is also examined as a function of \epsilon_{r} and h . It is shown that even for thin substrates, multiple-beam radiation can result for certain values of \epsilon_{r} by the excitation of surface waves. Multiple-beam patterns can also be obtained with increasing h for a given \epsilon_{r} . In fact as h increases it is determined that the resonant length, bandwidth, and resonant resistance approach the apparent value of a PCD on a dielectric halfspace.
128 citations
TL;DR: In this paper, an open-ended coaxial line was used as a sensor in measurement of the permittivity of lossy dielectrics at radio and microwave frequencies, and a simplified equivalent circuit related the permitivity to the measured input reflected coefficient.
Abstract: An open-ended coaxial line was used as a sensor in measurement of the permittivity of lossy dielectrics at radio and microwave frequencies. A simplified equivalent circuit related the permittivity to the measured input reflected coefficient. A more complete equivalent circuit is proposed and errors in the permittivity measurements resulting from the simplification are analyzed.
108 citations
TL;DR: In this article, 13 well-known formulas for dielectric permittivity of mixtures are examined in order to select the best model for the description of dielectrics properties of moistened soil.
Abstract: Thirteen well-known formulas for dielectric permittivity of mixtures are examined in order to select the best model for the description of dielectric properties of moistened soil. The selection of the best model is made by comparing theoretical results and experimental data.
75 citations
TL;DR: In this paper, an attempt is made to apply dielectric theories of interfacial polarization to observations of dielectrics relaxations for W/O emulsions, and the authors conclude that the dielectral relaxations due to the interfacial polarities of dispersed systems of spheres are explained satisfactorily by the theory for concentrated disperse systems.
Abstract: An attempt is made to apply dielectric theories of interfacial polarization to observations of dielectric relaxations for W/O emulsions. Approximate formulas for disperse systems in a W/O type were derived from the two theories: one proposed by Maxwell and Wagner for dilute disperse systems of spherical particles, and the other developed by Hanai for concentrated disperse systems. Dielectric measurements were carried out on concentrated W/O emulsions prepared from kerosene and distilled water or KCl aqueous solutions by minimal use of emulsifiers. Marked dielectric relaxations were observed with the emulsions, the dielectric parameters having been determined to characterize the relaxation data. Phase parameters such as relative permittivity, electric conductivity and volume fraction of the disperse phase were evaluated from the dielectric parameters by use of the approximate formulas of the respective theories. The phase parameters evaluated and the frequency dependence of complex permittivity of the W/O emulsions deduced from the theory for concentrated disperse systems are in excellent agreement with the observed data in comparison to that for dilute disperse systems. It is concluded that the dielectric relaxations due to the interfacial polarization of disperse systems of spheres are explained satisfactorily by the theory for concentrated disperse systems.
57 citations
TL;DR: The theoretical treatment developed in the preceding companion paper I has been applied to measurements made in conditions chosen to provide a critical test as mentioned in this paper, and the refractive index can be measured to within 0.5% (and thus the permittivity to within 1%) even with unfavourable combinations of frequency, thickness of specimen, and permittivities.
Abstract: The theoretical treatment developed in the preceding companion paper I has been applied to measurements made in conditions chosen to provide a critical test. The refractive index can be measured to within 0.5% (and thus the permittivity to within 1%) even with unfavourable combinations of frequency, thickness of specimen, and permittivity.
39 citations
TL;DR: In this paper, the combined effects of dielectric saturation and friction on ionic motion in polar solvents are solved numerically to yield ionic conductances, and the results of the analysis are critically tested by comparison with experimental conductance data.
Abstract: Electrohydrodynamic equations developed by Hubbard and Kayser to account for the combined effects of dielectric saturation and dielectric friction on ionic motion in polar solvents are solved numerically to yield ionic conductances. Dielectric saturation is incorporated into this continuum treatment through a phenomenological relationship between the electric permittivity and field strength. The results of the analysis are critically tested by comparison with experimental conductance data.
38 citations
TL;DR: Artemia cysts are composed of an inner mass of about 4000 cells surrounded by an acellular shell that can undergo cycles of hydration-dehydration without viability loss, and is a useful model for the study of intracellular water.
TL;DR: In this paper, the complex permittivity and emissivity of the body, and attenuation coefficient of skin were determined from simple measurements made on living human tissue over the frequency range 8 to 18 GHz.
Abstract: The complex permittivity, and hence the emissivity, of the body, and the attenuation coefficient of skin were determined from simple measurements made on living human tissue over the frequency range 8 to 18 GHz.
TL;DR: In this paper, the complex relative permittivity of polyethylene/mica composites has been measured in the frequency range 10-2 to 107 Hz, as a function of mica content and prior sample conditioning.
Abstract: The complex relative permittivity ?*(f) of polyethylene/mica composites has been measured in the frequency range 10-2 to 107 Hz, as a function of mica content ?2 and prior sample conditioning. ?*(f) was found to display two main features: ?'-?' ?and K'' vary as fn-1 with 0.64?n?0.83 for all ?2, on account of the intrinsic dispersive properties of the mica. In addition, K'' displays a broad peak centered in the audio frequency range, associated with ?Maxwell-Wagner-Sillars? losses due to absorbed water. Finally, the high frequency permittivity K'? is compared with various ?mixture formulae in the literature; Sillars' theory is found to fit experimental data well, even at high ?2 values.
TL;DR: In this paper, a resonant system for the measurement of the complex permittivity in the 0.1 MHz-300 MHz range is presented, which can easily fit the measurement cells of the laboratory used in the 1 Hz-4 GHz range.
Abstract: A device for the measuring of the complex permittivity in the 0.1 MHz-300 MHz range is presented. It is a resonant system on which we can easily fit the measurement cells of the laboratory used in the 1 Hz-4 GHz range. This device allows us to measure the loss angle of materials down to 0.4*10-3. After the description of the mechanical and electronic parts of the device, the authors give the calibration method used to obtain the real and imaginary components of the electric permittivity. Finally, they report the results of dielectric measurements performed with this device for a liquid crystal and a synthetic zeolite. Automatic data processing by means of a computer increases the rapidity of measurement and decreases the number of manual operations.
TL;DR: In this paper, the edge effects of introducing a dielectric test cylinder with a test material into a cavity via a metallic support tube extending outside the cavity were examined, and the Galerkin method was used to determine the amplitudes of numerous evanescent modes which exist in such composite hole geometries.
Abstract: This paper examines the edge effects of introducing a dielectric test cylinder with a test material into a cavity via a metallic support tube extending outside the cavity. A first-order perturbation theory is used for this metallic hole containing two different concentric dielectric materials. The Galerkin method is used to determine the amplitudes of numerous evanescent modes which exist in such composite hole geometries. Comparisons are made with the effects produced by a simple hole in which a single dielectric is postulated inside the metallic support tribe. The effects of the composite hole on the measurement of the dielectric properties of materials are given.
TL;DR: In this article, the equilibrium phase diagram for the AgI Ag 4 P 2 O 7 system of fast-ion electrolyes is established along with the conductivity-composition relationship for polycrystalline samples.
TL;DR: In this paper, a new dielectric measurements method in the range 200 MHz-18 GHz is reported, which can automatically determine the sample complex permittivities for each step of frequency previously chosen by using a numerical process, and cells requiring only a very small sample volume (typically lower than.1 cm/sup 3/).
Abstract: In this paper a new dielectric measurements method in the range 200 MHz-18 GHz is reported. The main features of the system are the following: a) automatic determination of the sample complex permittivities for each step of frequency previously chosen by using a numerical process; b) cells requiring only a very small sample volume (typically lower than .1 cm/sup 3/); and c) cell structure allowing the dielectric characterization of anisotropic substances.
01 Dec 1982
TL;DR: In this paper, the authors describe the design of a probe for in situ measurement of the relative permittivity and relative permeability of soil at vhf, which is a semi-automatic method of data reduction, programmable on a pocket calculator and therefore suitable for direct field use.
Abstract: This paper describes the design of a probe for in situ measurement of the relative permittivity and relative permeability of soil at vhf. A semi-automatic method of data reduction, programmable on a pocket calculator and therefore suitable for direct field use, is developed. A demonstration version of the probe has been produced. Tests on a dielectric material with known properties suggest that the readings which it produces are reliable to an accuracy of a few per cent. A series of measurements has been made on soil samples; not surprisingly these emphasise the dominant role of water content in determining dielectric constant. (Author/TRRL)
DOI•
01 Apr 1982TL;DR: In this article, a description of two TE01 partially filled microwave cavity resonators operating at 10 and 35 GHz, respectively, is given. The cavities are the principal components in two dielectric measurement systems which have been used to determine the complex permittivity of low-loss liquids at room temperature.
Abstract: A description is given of two TE01 partially filled microwave cavity resonators operating at 10 and 35 GHz, respectively. The cavities are the principal components in two dielectric measurement systems which have been used to determine the complex permittivity of low-loss liquids at room temperature. In particular, we report measurements of the dielectric properties of the members of the normal alkane series from pentane to tetradecane, inclusive.
TL;DR: In this paper, the optical absorption of six n-alkanes (n-pentane to n-decane) has been measured in the far infrared using the Grubb-Parsons Mark III interferometer.
Abstract: The optical absorption of six n-alkanes (n-pentane to n-decane) has been measured in the far infrared using the Grubb-Parsons Mark III interferometer. The results are related to low frequency permittivity, microwave loss, and refractive index measurements using the Kramers-Kronig relation.
TL;DR: In this paper, the state of progress of a polymerization reaction by a non-destructive electric method is characterized by comparing the results deduced from measurements of complex permittivity with those obtained from chemical analysis of the reaction mixture at successive instants of its evolution.
Abstract: The aim of this study is to characterize the state of progress of a polymerization reaction by a non-destructive electric method. For this purpose, results deduced from measurements of complex permittivity are compared with those obtained from chemical analysis of the reaction mixture at successive instants of its evolution. Chemical analysis allows the rate of disapperace of expoxy groups during the polymerization reaction in liquid phase to be evaluated. Exploitation of electric measurements of complex relative permittivity enables the evolution of the polymerization to be followed from both the product of the epoxy group concentration and the square of the mean value of their dipole moment and also from the most probable relaxation time of this dipole. As expected, the variations of relaxation time are closely correlated to those of the viscosity of the medium.
TL;DR: In this article, a coaxial line transmission cell is described which allows accurate permittivity measurements to be made on lossy liquids over the frequency range 90 MHz to 2 GHz.
Abstract: A coaxial line transmission cell is described which allows accurate permittivity measurements to be made on lossy liquids over the frequency range 90 MHz to 2 GHz. To test the performance of the cell, measurements were made on water, methanol and ethanol at 293K.
TL;DR: In this paper, the behavior of the dielectric permittivity of a mixture of disperse materials with change in volume content of the component with high water and temperature is investigated.
Abstract: The behavior of the dielectric permittivity of a mixture of disperse materials with change in volume content of the component with high dielectric permittivity (water) and temperature is investigated. An analysis of the results is presented. A formula is given for the calculation of the dielectric permittivity of moist disperse materials as a function of the temperature.
TL;DR: In this paper, the authors presented a rigorous analysis of symmetric, broad-side-coupled slot line with overlay, where the structure is assumed to be suspended inside a conducting enclosure of arbitrary dimensions.
Abstract: This paper presents a rigorous analysis of symmetric, broad-side-coupled slot line with overlay. The structure is assumed to be suspended inside a conducting enclosure of arbitrary dimensions. The dielectric substrate and the overlay are assumed to be isotropic and homogeneous and are of arbitrary thickness and relative permittivity. The conducting enclosure and the zero thickness metallization on the substrate are assumed to have infinite conductivity. The computed results illustrate a) the dispersion characteristics and characteristic impedance of the coupled slot line structure, b) the variation of the even-mode and also the odd-mode relative wavelength ratio and characteristic impedance with slot width, and c) the effect of shielding on the even-mode and also the odd-mode dispersion and characteristic impedance. This structure should find application in the design and fabrication of MIC components such as magic-T's and directional couplers.
TL;DR: In this paper, the charge transfer interaction between triethylamine (Et3N) and iodine has been studied in the solvents of different dielectric permittivity, using conductometric, refractometric and differential refractometric techniques.
TL;DR: In this article, a method for far infrared laser measurements is described and the limits of its validity are given, as well as a method to calculate the permittivity of a sample.
Abstract: It is very difficult to measure the optical constants of solids by reflection and transmission whenever the real part of the permittivity becomes negative. However, if this permittivity is sufficiently small, surface waves may form in a sample. These may be excited and their dispersion can be determined experimentally. The dispersion can then be used to calculate the permittivity. A method for far infrared laser measurements is described and the limits of its validity are given.
01 Oct 1982
TL;DR: In this article, the basic equations for pressure-pulse and pressure-step experiments are derived from first principles and the pressure dependence of the relative permittivity e is investigated, and the influence of this dependence on the signal amplitude is calculated for nonpolar and for polar dielectrics.
Abstract: Detailed knowledge of the electric charge or field distribution in the bulk of dielectrics is necessary for the understanding of charge-storage and charge-transport phenomena. The most successful techniques for the experimental determination of spatial charge or field distributions in dielectrics, are based on the transit of a compression wave through the sample [1-6]. In the present study, the basic equations for pressure-pulse and pressure-step experiments are derived from first principles. The pressure dependence of the relative permittivity e is investigated, and the influence of this dependence on the signal amplitude is calculated for nonpolar and for polar dielectrics. The response equations for pressure-step, pressure-pulse and arbitrary pressure-profile experiments are calculated.
TL;DR: In this article, the permittivity measured at a frequency of 10 GHz normalized to constant density is the same within the experimental error for talc, baryte and dolomite.
Abstract: The permittivity measured at a frequency of 10 GHz normalized to constant density is the same within the experimental error for talc, baryte and dolomite. In the case of clay and kaolin, it is about 10% higher. This is attributed to the high content of Al2O3 (30–40%) in them, which interpretation is proved by experiment.
15 Jun 1982
TL;DR: In this article, a numerical method and the effective index method are applied to a three-layer, constant thickness dielectric waveguide with smoothly varying Dielectric constant inside the active layer and constant permittivity in the confining layers.
Abstract: A numerical method and the effective-index method are applied to a three-layer, constant thickness dielectric waveguide with smoothly varying dielectric constant inside the active layer and constant permittivity in the confining layers. The results of the two methods are compared in terms of the propagation constant gamma calculated by each method. Application of the effective-index method facilitates a physical understanding of dielectric waveguide modes as well as providing an efficient approximate method for calculating mode behavior.