Showing papers on "Relative permittivity published in 1970"
TL;DR: In this article, a resonant post technique for characterizing dielectric and magnetic materials at microwave frequencies was proposed and experimental results of the temperature dependence of the relative dielectrics constant of nonmagnetic materials with /spl epsilon/sub r/, varying from 4 to 60, and also loss tangent measurements at room temperature.
Abstract: Theory and experimental results are presented to show the possibility of using a resonant post technique for characterizing dielectric and magnetic materials at microwave frequencies. Results of the temperature dependence of the relative dielectric constant of nonmagnetic materials with /spl epsilon//sub r/, varying from 4 to 60 are presented and also loss tangent measurements at room temperature. The complex permittivity and permeability of a number of garnet materials has also been measured with 4/spl pi//spl gamma/M/sub s/ / /spl omega/ varying from 0.25 to 0.8. The measured real part of the permeability is in good agreement with the theoretical predictions of Schlomann and the imaginary part of the permeability agrees with measurements by Green et al. on similar materials.
1,247 citations
TL;DR: In this paper, it was shown that the experimentally observed temperature dependence of the static permittivity of water is completely accounted for by the decrease of the high-frequency permittivities with increasing temperature, so that there is no evidence for a correlation parameter differing appreciably from unity at any temperature.
Abstract: It is shown that the experimentally observed temperature dependence of the static permittivity of water is completely accounted for by the decrease of the high-frequency permittivity with increasing temperature, so that there is no evidence for a correlation parameter differing appreciably from unity at any temperature.
48 citations
TL;DR: In this paper, a method for calculating the effective complex permittivity of a solid dielectric arising from the motion of charge carriers which are blocked at the electrodes is presented.
Abstract: A method has been developed for calculating the effective complex permittivity of a solid dielectric arising from the motion of charge carriers which are blocked at the electrodes The method makes use of computer simulation of the motion of the charge carriers and is valid for high voltages Results are given of calculations carried out for a simple model with charge carriers of only one sign mobile Diffusion effects are neglected The effective complex permittivity is then found to depend on only two parameters The dielectric dispersion is found to exhibit a well-defined loss peak whose frequency can, show a strong voltage dependence
45 citations
01 Sep 1970
TL;DR: In this paper, the authors describe a technique for the automated measurement and display of the relative permittivity and loss factor of insulating materials over the frequency range 10−4 to 106Hz.
Abstract: Newly developed techniques are described for the automated measurement and display of the relative permittivity and loss factor of insulating materials over the frequency range 10−4 to 106Hz. The principle of operation is to sample, at logarithmically spaced times, the charge-time response to a voltage step of a capacitor containing a specimen of the material. Approximate transforms, developed for this application, are then applied to these data and the steady-state material parameters are presented as a permanent record in analogue form at discrete frequencies spaced at octave intervals. Apart from a brief initial setting-up operation, the process is automatic, and the time taken to describe a complete spectrum is 40s for one instrument which covers the frequency range 1 to 106Hz; in about 15min another covers 10−4 to 102Hz. The present embodiments are most suited to materials having loss factors greater than about 10−3. Factors limiting accuracy and resolution are discussed.
31 citations
TL;DR: In this paper, the complex dielectric permittivity for four granular solids with different water-bonding forces have been measured at a frequency of 9.4 GHz and the modified very-long-sample method was employed.
Abstract: Measurements of the complex dielectric permittivity for four granular solids with different water-bonding forces have been performed. Sand, powdered mashed potato powder, and silica gel were tested at a frequency of 9.4 GHz and the modified very-long-sample method was employed. The existence of two ranges of water bonding was confirmed. In the first range, which is below the critical moisture content point, the water appears to have low permittivity because of large adsorption forces, and in the second range free water with high permittivity prevails.
26 citations
TL;DR: In this article, a numerical method for rectangular waveguides containing a transversely inhomogeneous dielectric rod is presented, where the electric and magnetic field strengths, the dispersion characteristics of the propagating modes, and the attenuation constants of the evanescent modes result from the solution of a matrix eigenvalue problem with typically 8000 matrix elements.
Abstract: A numerical-calculation method for rectangular waveguides containing a transversely inhomogeneous dielectric is presented. The method is not restricted to the cutoff case or to special inhomogeneities. The relative permittivity of the dielectric can be an arbitrary function of the cross-sectional coordinates. The electric-and magnetic-field strengths, the dispersion characteristics of the propagating modes, and the attenuation constants of the evanescent modes result from the solution of a matrix eigenvalue problem with typically 8000 matrix elements. Propagating and evanescent modes in a waveguide containing a longitudinal semicircular dielectric rod are calculated as examples. The accuracy of the calculation method is confirmed by measurements and by calculating a special example with an exactly known solution. The error of the field intensities is typically 5 percent; the error of the dispersion characteristics and of the attenuation constants is typically 0.5 percent.
19 citations
TL;DR: In this article, the paraelectric to ferroelectric transition was shown to be an isothermal transformation and the antiferroelectric phase transformed into a paralectric phase.
Abstract: Constant temperature permittivity measurements of ceramic lead zirconate near 230°C revealed that the paraelectric to ferroelectric, ferroelectric to antiferroelectric, and antiferroelectric to paraelectric phase transitions were isothermal transformations. On heating, the antiferroelectric phase transformed into a paraelectric phase. Cooling produced a transformation from the paraelectric into an intermediate ferroelectric phase which existed over a temperature range of about 5°C. On further cooling, the ferroelectric transformed into the antiferroelectric phase. Thermal expansion, relative permittivity, and dissipation factor data are reported.
18 citations
TL;DR: In this article, a microstrip ring resonator on a calcium-zirconate substrate shows the dispersion predicted theoretically; the effective permittivity increases from 17 to 23 over the frequency range 1-12 GHz and gives 28.1 as the calculated real value of the permittivities of the substrate.
Abstract: Ceramics comprising homogeneous single-phase zirconate solid solutions of suitable composition have very low temperature coefficients of permittivity, low-frequency permittivities of 30–40 and low losses. Dielectric resonators give Q values up to 4000 and permittivities of 28–35 at 4–5 GHz. The effective permittivity measured on a microstrip ring resonator on a calcium-zirconate substrate shows the dispersion predicted theoretically; the effective permittivity increases from 17 to 23 over the frequency range 1–12 GHz and gives 28.1 as the calculated real value of the permittivity of the substrate. The measured Q value of 200 indicates negligible dielectric losses compared with the I2R losses.
15 citations
TL;DR: In this paper, a dielectric cell for investigating high permittivity liquids has been designed for use with a radio frequency admittance bridge, which has negligible self-inductance below 100 MHz and requires no corrections in its use.
Abstract: A dielectric cell for investigating high permittivity liquids has been designed for use with a radio frequency admittance bridge. The cell has negligible self-inductance below 100 MHz and thus requires no corrections in its use. Details are given for modifying the bridge terminals when temperature control of the system is required.
14 citations
TL;DR: In this paper, the influence of the mobile phase permittivity on the sensitivity and linearity of detection by the capacitance detectors has been investigated theoretically, and relations have been derived between the response and the concentration for the interference and bridge methods.
12 citations
TL;DR: In this paper, the behavior of an adjustable length of coaxial line containing a standing wave is considered theoretically and a relationship can be obtained between the change in the line length and the resulting change of phase.
Abstract: The behaviour of an adjustable length of coaxial line containing a standing wave is considered theoretically. It is shown that a relationship can be obtained between the change in the line length and the resulting change of phase. This is then followed by a description of how the complex permittivity of a liquid such as water can be measured using the phase changer in conjunction with a phase-amplitude balance method.
11 May 1970
TL;DR: In this article, the problem of determining the scattered electromagnetic fields when a dielectric step discontinuity is placed in a waveguide is considered, and the recently introduced modified residue-calculus technique (MRCT) can be successfully extended to obtain a very accurate and numerically efficient approximate solution of the semi-infinite Dielectric Step.
Abstract: The problem of determining the scattered electromagnetic fields when a dielectric step discontinuity is placed in a waveguide is considered. Although an exact method of solution is not presently known, the recently introduced modified residue-calculus technique (MRCT) can be successfully extended to obtain a very accurate and numerically efficient approximate solution of the semi-infinite dielectric step. A still further extension of the modified residue-calculus method yields the approximate solution for the case of a finite dielectric step. A unique advantage of the present methods is that the degree of accuracy obtained is independent of the relative permittivity of the dielectric material and of the frequency. Thus very high permittivities or frequencies can be considered without an attendant increase in computational complexity. Numerical data are presented which confirm the accuracy of the method.
TL;DR: In this article, a method for measuring the complex permittivity of a liquid contained in a short-circuited line is presented, which consists of plotting a standing wave pattern and comparing this with the theoretically predicted waveform.
Abstract: A method is given for measuring the complex permittivity of a liquid contained in a short-circuited line. Basically, the technique consists of plotting a standing wave pattern and comparing this with the theoretically predicted waveform. This is an improvement on previous methods in that the dielectric properties of a lossy liquid with poorly defined maxima and minima can be investigated; moreover, a liquid with a low permittivity and a first minimum lying outside the range of measurement can be examined. A method is also given for improving the capabilities of the standard least squares computer analysis when parameter information from the data is low, or when the initial parameter estimates are far away from the correct value.
01 Apr 1970
TL;DR: In this article, the angular spectrum of plane waves was used for the problem of mode propagation in a rectangular waveguide loaded with a single E plane dielectric slab, and the dispersion equation for the modes in one slab was derived and the computed eigenvalues were verified by comparison with the recent results of Gardiol, based on a matrix boundary-value solution, and Kashyap and Hamid, and by a perturbation analysis.
Abstract: The application of the angular spectrum of plane waves, previously shown by Robinson, and Hamid for the problem of mode propagation in a rectangular waveguide loaded with a single E plane dielectric slab, is extended to an arbitrary number of slabs. The technique employs ray optics and residue calculus and is developed to the point where considerable theoretical advantages are evident when dealing with the more general case of a waveguide loaded with an arbitrary number of lossy or lossless dielectric slabs and excitation by a discrete set of propagating modes or inhomogeneous line sources. To illustrate the procedure for the case of three slabs, the dispersion equation for the modes in one slab is derived and the computed eigenvalues are verified by comparison with the recent results of Gardiol, based on a matrix boundary-value solution, and Kashyap and Hamid, based on a perturbation analysis. The transverse electric-field distribution is extended to the other slabs so that the boundary conditions at the interface of two planar dielectric slabs are satisfied. Plots of the transverse electric field due to propagating modes for a particular case are also presented and shown to converge when only the first few modes are considered. It is found that the frequency bandwidth, defined as the separation between the cutoff frequencies of the dominant and next highest-order mode, may be increased or decreased over the unloaded waveguide depending on the physical dimensions and relative permittivity of the slabs.
TL;DR: In this paper, complete dielectric saturation in solutions of prolate or oblate macromolecules aligned in an intense electric field is discussed quantitatively, and a positive effect was measured in solution of isotactic polystyrene in benzene.
TL;DR: In this article, the performance of a 50-ohm microstripline ferrite substrate was optimized to give a forward loss of 5 dB with a reverse loss in excess of 30 dB at resonance.
Abstract: Resonance isolators operating at X -band frequencies have been constructed in conventional 50-ohm microstripline by positioning ferrite strips on the surface of the alumina substrate adjacent to the stripline conductor A transverse external magnetic field is applied in the plane of the surface to obtain the necessary Kittel resonance condition It is shown that by suitable choice of ferrite dimensions the performance may be optimized to give a forward loss of 05 dB together with a reverse loss in excess of 30 dB at resonance The influence of saturation magnetization of the ferrite as well as relative permittivity of the substrate material has also been examined Nonreciprocal phase shift may be obtained by using this geometry; but high external field is required to saturate the ferrite A modification employing an all-ferrite substrate, which may be used to design a phase shifter operated at remanence, is described
TL;DR: In this article, the numerical method used at Istituto di Elettronica dell'Universita di Pisa, Italy, for processing experimental data obtained in measuring complex dielectric permittivity by dielectrometer.
Abstract: The letter describes the numerical method used at Istituto di Elettronica dell'Universita di Pisa, Italy, for processing experimental data obtained in measuring complex dielectric permittivity by dielectrometer. The letter shows that it is possible to obtain high-precision results without using Von Hippel tables.
TL;DR: The attenuation constant for microstrip lines on fused quartz and their effective relative dielectric constant were measured and the results are discussed in this article, where the conductors were deposited without an adhesive layer but with sufficient adhesion for pressure bonding semiconductor chips.
Abstract: The attenuation constant for microstrip lines on fused quartz and their effective relative dielectric constant were measured and the results are discussed. The propagation losses in these lines proved to be smaller than those mentioned in the literature. The effective relative dielectric constant is found to be independent of frequency up to 12 GHz. The conductors were deposited without an adhesive layer but with sufficient adhesion for pressure bonding semiconductor chips.
01 Sep 1970
TL;DR: In this article, a method for extracting a relaxation spectrum from experimental data is described, where the data are functions of frequency, viz., complex permittivity in dielectric work and complex viscosity in viscoelasticity.
Abstract: The difficulty of extracting a relaxation spectrum from experimental data is well known. The data are functions of frequency, viz., complex permittivity in dielectric work and complex viscosity in viscoelasticity. A method is described which obtains the spectrum by a simple numerical calculation.
TL;DR: In this paper, the dielectric constant and loss in liquid-ammonia solutions of alkali halides have been measured in the frequency range 0.7 - 70 GHz and at least one relaxation process exists in this frequency range in addition to the relaxation of the solvent molecules.
Abstract: Abstract Dielectric constant and loss in liquid-ammonia solutions of alkali halides have been measured in the frequency range 0.7 - 70 GHz. At least one relaxation process exists in this frequency range in addition to the relaxation of the solvent molecules. The additional relaxation is ascribed to the orientational polarisation of ion pairs. The concentration of the ion pairs, calculated with a special model, is 30 - 50% of the total concentration. The interaction between ions and solvent molecules is discussed.
Patent•
16 Feb 1970TL;DR: In this paper, a ferroelectric material having its permittivity dependent on temperature is disposed partially in an electric field between a pair of capacitor plates, where a heat source is provided to heat the material just outside the capacitor plates so that a force pulls the heated portion into the field.
Abstract: A ferroelectric material having its permittivity dependent on temperature is disposed partially in an electric field between a pair of capacitor plates. A heat source is provided to heat the ferroelectric material just outside the capacitor plates to increase the permittivity above that existing between the capacitor plates so that a force pulls the heated portion into the field. The force is enhanced by providing a liquid of high permittivity between the ferroelectric material and the capacitor plates. By using a liquid having a permittivity between the upper and lower extremes of the ferroelectric material, a force is produced pushing the ferroelectric material, when cooled, out of the field.
TL;DR: In this paper, the detailed way of assembling capacitors for the absolute determination of permittivity of liquids is described, and sources of errors and precautions to be taken are discussed.
Abstract: The detailed way of assembling capacitors for the absolute determination of permittivity of liquids is described. Sources of errors and precautions to be taken are discussed. The following results of measurements of the permittivity of various commercial benzenes (referred to air of about 30% humidity) at 20°C were obtained: Sample I: 20=2·2841 ± 0·0001; sample II: 20=2·2858 ± 0·0002; sample III: 20=2·2857 ± 0·0002; sample IV: 20=2·2879 ± 0·0002. The temperature dependence has been also investigated.