Showing papers on "Relative permittivity published in 1975"
TL;DR: In this article, it was shown that the modes of a dielectric resonator are of two types: confined and non-confined, and their radiation pattern and quality factor were investigated.
Abstract: It is shown that the modes of a dielectric resonator are of two types: confined and nonconfined. Orthogonality properties and variational principles are derived for these modes, and their radiation pattern and quality factor are investigated. The material of the resonator is assumed lossless and of very high permittivity.
140 citations
TL;DR: In this paper, the electric permittivity of nematic 44′ n-pentylcyanobiphenyl has been measured in the presence of electric and magnetic fields.
Abstract: The electric permittivity of nematic 44′ n-pentylcyanobiphenyl has been measured in the presence of electric and magnetic fields. Values of the permittivity components for the aligned state have been obtained and analysed in terms of the statistical theory of Maier and Meier. The behaviour of bulk samples of the material in electric and magnetic fields has been investigated, and yielded a mean permittivity for the non-aligned state. The macroscopic behaviour is discussed in terms of the continuum theory. Variable frequency measurements have shown the presence of a dispersion region in e∥ at about 5 MHz.
126 citations
TL;DR: In this paper, a planar waveguide model with a frequency-dependent effective relative permittivity and a frequencydependent effective width was developed for the open microstrip line, which was shown by experimental results from measurements with a resonator and a sliding-load technique.
Abstract: A planar waveguide model with a frequency-dependent effective relative permittivity and a frequency-dependent effective width is developed for the open microstrip line. The validity of this waveguide model is shown by experimental results from measurements with a resonator and a sliding-load technique.
122 citations
TL;DR: In this paper, the relative permittivity of polycrystalline and single-crystal ice at 35 and 60 MHz in the temperature range −25°C to −0.2°C was investigated.
Abstract: The relative permittivity ∊’ and attenuation α in laboratory-grown, polycrystalline and single-crystal ice Ih are reported at 35 and 60 MHz in the temperature range —25°C to — 0.2 ° C. The ∊’ and α at 35 MHz and — 1° C are 3.208±0.010 and 6.2±0.1 dB/100 m, respectively. From a comparison between the respective ∊’ and α of the polycrystalline and single-crystal ice measured perpendicular to the c-axis, it is concluded that any anisotropy of polarization at these frequencies is so small as to be undetectable. Amongst several factors that may contribute to anisotropy in ice, electronic polarization contributes 0.0037 to the difference between the relative permittivity measured parallel and perpendicular to the c-axis at — 1° C and at frequencies less than 500 THz. Experiments have shown that the plastic deformation resulting from a uniaxial compressive stress of up to 100 bar does not influence the ∊’ and α of ice at 35 and 60 MHz.
79 citations
77 citations
TL;DR: In this article, the response of a dielectric resonator excited by either interior volume sources or incident exterior waves is investigated, and special attention is devoted to phenomena at resonace, and in particular to the induced electric and magnetic dipoles.
Abstract: The response of a dielectric resonator excited by either interior volume sources or incident exterior waves is investigated. Special attention is devoted to phenomena at resonace, and in particular to the induced electric and magnetic dipoles. Simple formulas are obtained for the scattering cross section. The material of the resonator is assumed lossless and of very high permittivity.
60 citations
TL;DR: In this article, a method has been developed for the precise nondestructive measurement of the dielectric constant and losses of slab-like samples such as microstrip substrates, for instance.
Abstract: A method has been developed for the precise nondestructive measurement of the dielectric constant and losses of slab-like samples such as microstrip substrates, for instance Basically, the test setup consists of an open-ended rectangular waveguide, the flange of which is placed in contact with one side of the dielectric material, the other one being backed by a metal plate The waveguide can be either simply cut at its end, or terminated by an inductive or capacitive iris The reflection characteristics or the resonance parameters are related to the real and imaginary parts of the permittivity by means of computer-generated charts or an optimization program
46 citations
TL;DR: In this article, two parallel plate cells have been designed for use with an RF admittance bridge to investigate the permittivity of aqueous solutions of biological interest in the frequency range 1-100 MHz.
Abstract: Two parallel plate cells have been designed for use with an RF admittance bridge to investigate the permittivity of aqueous solutions of biological interest in the frequency range 1-100 MHz. A simple substitutional technique is used to correct for inductance and any second order effects in the apparatus. The versatility of the apparatus is illustrated by the achievement of +or-0.2 in the permittivity for aqueous solutions of conductivity up to 2.5*10-2 Omega -1 m-1. The performance of the bridge is demonstrated with results taken on ethane diol and on solutions of human low density lipoproteins (LDL).
31 citations
TL;DR: In this article, a method for determining the effective relative permittivity of microstrip, even at high frequencies, was presented, where four microstrips having the same physical and geometric characteristics, but different lengths, are needed; the mismatch due to the launchers is completely overcome.
Abstract: A new method for determining the effective relative permittivity of microstrip, even at high frequencies, is presented. Four microstrips having the same physical and geometric characteristics, but different lengths, are needed; the mismatch due to the launchers is completely overcome.
28 citations
TL;DR: In this article, a lumped capacitance method for measurement of the permittivity and conductivity of materials in the radio and microwave frequency ranges is presented, and the analysis of the method applicable in both frequency and time domains is given for materials having low frequency conductivity or Debye dispersion.
Abstract: Further discussion of a lumped capacitance method for measurement of the permittivity and conductivity of materials in the radio and microwave frequency ranges is presented. The analysis of the method applicable in both frequency and time domains is given for materials having low frequency conductivity or Debye dispersion.
TL;DR: In this paper, a non-structive microwave cavity approach for measuring complex permittivities of materials in sheet form is described, where the resonant cavity is a section of a rectangular waveguide terminated by a thin rigid and large flange containing a small rectangular iris opening and the iris is placed in firm contact with one side of the dielectric sample while the other side is backed with a highly conducting plate.
Abstract: A nondestructive microwave cavity approach for measuring complex permittivities of materials in sheet form is described. The resonant cavity is a section of a rectangular waveguide terminated by a thin rigid and large flange containing a small rectangular iris opening. The iris is placed in firm contact with one side of the dielectric sample while the other side is backed with a highly conducting plate. Variations of the cavity resonant frequency and Q-factor caused by the dielectric can be related to its complex permittivity through the consideration of equivalent admittance of this open-ended dielectricloaded aperture at resonance. Experimental determination of aperture admittance of a loaded iris is made and the results compared with theoretical calculations. The validity of this technique is confirmed by evaluating the resonant cavity characteristics by loading it with dielectrics of known permittivities and comparing the results with theoretical results. The permittivity of a lossy dielectric slab is measured and the value obtained by this method is compared with those found by other techniques. In all these cases the agreement between theory and measurements is satisfactory. Utility of this technique in evaluating the local inhomogeneities of permittivity of sheets is demonstrated. Measurement errors and limitations of this technique are pointed out.
TL;DR: Closed-form expressions are obtained for the impulse response of graded-index fibers whose relative permittivity is a homogeneous function of the two transverse coordinates x, y, and forThe impulse width in graded- index fibers whose profile departs slightly, but otherwise arbitrarily, from a square law.
Abstract: Closed-form expressions are obtained for the impulse response of graded-index fibers whose relative permittivity is a homogeneous function of the two transverse coordinates x, y, and for the impulse width in graded-index fibers whose profile departs slightly, but otherwise arbitrarily, from a square law. The inhomogeneous dispersion of the material is taken into account. Pulse broadening can be reduced by a factor of 12 from the value obtained for square-law fibers. Simple expressions are found for the acceptance of highly oversized fibers.
TL;DR: In this paper, a technique for computing the spatial variation of dielectric permittivity in waveguides, directly from the distribution with mode number of the mode indices, is presented.
Abstract: A technique is presented for computing the spatial variation of dielectric permittivity in waveguides, directly from the distribution with mode number of the mode indices. The method applies to two-dimensional as well as to three-dimensional axially symmetric media in which the permittivity varies only in a direction transverse to the axis of guidance. It provides a means for inverting the well-known WKB formula for mode guidance, and by design contains only the limitations that are inherent in the WKB asymptotic method.
TL;DR: In this paper, a simple millimeter reflecto-interferometric method, which allows for a very accurate determination of the complex permittivity of highly absorbing liquids, is proposed.
Abstract: A simple millimeter reflecto-interferometric method, which allows for a very accurate determination of the complex permittivity of highly absorbing liquids, is proposed. Results are given for water, formamide (CH3.NO) and ethylene-glycol (CH.2OH-CH2OH).
01 Feb 1975
TL;DR: In this paper, the optimal contact angle of a disc-type spacer is determined according to the relative permittivity of the spacer for R2/R1 (ratio of inner and outer electrode radii) = 1/3.
Abstract: By adopting the suitable contact angle of a disc-type spacer, the surface flashover may be effectively suppressed on account of the decrease of the maximum field strength at the spacer surface. The calculation has clarified that the optimal contact angle of the spacer is 60–70° according to the relative permittivity of the spacer for R2/R1 (ratio of inner and outer electrode radii) = 1/3, and that 20–30% decrease in the maximum strength can be brought about in various spacer-electrode arrangements. The effect on the field-relaxation of R2R1, the relative permittivity of the spacer, and the spacer shape have been studied. Experiments in air at atmospheric pressure and in compressed SF6 have verified that very few flashovers take place at the surface of the field-relaxing spacers.
TL;DR: In this article, the non-linear electric field effect of the relative permittivity of aqueous systems at fields up to 107 V m −1 was studied and it was shown that the Piekara factor (ΔIµ/E2) for water has the Langevin anticipated negative values but shows a distinct pattern with a minimum near 277 K.
Abstract: Measurements are reported on the non-linear electric field effect of the relative permittivity of aqueous systems at fields up to 107 V m–1. Over the range 273–293 K the Piekara factor (ΔIµ/E2) for water has the Langevin anticipated negative values but shows a distinct pattern with a minimum near 277 K. H2O and D2O liquids give indistinguishable values.Whilst acetone and pyridine show an essentially smooth variation of (ΔIµ/E2) over their complete concentration ranges in water, dioxan and tetrahydrofuran show similar marked variations with a distinctive positive effect near the hemihydrate compositions. The influence of temperature on the sharp positive maxima with these two solutes is reported. t-Butyl alcohol, well known to give positive (ΔIµ/E2) values in the pure liquid, does so at all concentrations above mole fraction 0.25. In many cases it is clear that the Piekara factor shows far more detail than the Iµ0 against concentration plots as the measurements are sensitive to very small changes in permittivity due to the high fields.The observations are discussed with the aim of identifying the principal factors contributing to the newly observed effects.
TL;DR: In this paper, the relative permittivity at frequencies of 1 MHz and 9.274 GHz and of the refractive index at sodium D-line have been carried out at 30°C for o-chlorobenzaldehyde (A), m-closest to ours, o-nitrobenzaldehyde (B), p-dioxane and Nujol, in dilute solutions of benzene, cyclohexane, carbon tetrachloride, etc.
Abstract: The measurements of the relative permittivity at frequencies of 1 MHz and 9.274 GHz and of the refractive index at sodium D-line have been carried out at 30°C for o-chlorobenzaldehyde (A), m-chlorobenzaldehyde (B), p-chlorobenzaldehyde (C), o-nitrobenzaldehyde (D), m-nitrobenzaldehyde (E), and P-nitrobenzaldehyde (F), in dilute solutions of benzene, cyclohexane, carbon tetrachloride, p-dioxane and Nujol. The dielectric relaxation times for the overall rotation and the electric dipole moments for these molecules have been calculated. These results have been used to calculate the dipole moment for the internal rotations, possibly of the CHO-group, in the molecule. The results are analyzed in terms of the solute-solvent interactions for these molecules. The bonding between the hydrogen atom of the aldehyde group and the oxygen atom of the dioxane molecule seems to be fairly weak. The comparative behavior of the chlorobenzaldehydes and the nitrobenzaldehydes has also been discussed.
TL;DR: In this article, a differential dielectric bridge is described for the measurement of small changes in the real and imaginary part of the dielectrics effected by the application of a strong static field to a liquid.
Abstract: A differential dielectric bridge is described for the measurement of small changes in the real and imaginary part of the dielectric permittivity effected by the application of a strong static field to a liquid. The apparatus is based on the resonant bridge principle and operates in the rf range (0.7−120 MHz). A dc field up to 250 kV/cm can be superimposed on the rf field. Chemical increments in the dielectric loss factor characteristic for chemical relaxation experiments of less than 1×10−7 are detectable. The apparatus can also be used as a conventional dielectric bridge whereby changes in the real part of 5×10−5 and in the imaginary part of the permittivity as low as 1×10−4 are measurable. The technique of the measurements is discussed and illustrative examples are provided.
TL;DR: In this article, the volume and surface loss functions have been calculated and the displacement of the volume plasmon energy from just below 7eV to over 9 eV was attributed to bound transitions in the regions of 5 eV.
Abstract: The reflectance of films of calcium has been measured at several angles of incidence in the energy range 6-30eV. The optical constants have been computed by an iterative process and the real and imaginary parts of the complex relative permittivity and the volume and surface loss functions have been calculated. The displacement of the volume plasmon energy from just below 7eV (as deduced from low energy optical measurements and as predicted by the free electron model) to over 9 eV (as found from the loss function, confirming electron energy loss measurements) is attributed to bound transitions in the regions of 5 eV.
TL;DR: In this paper, a theoretical and experimental analysis of a simple lumped element model representing multiple reflection time domain spectroscopy (TDS) is presented, where an analytical expression is derived relating the experimentally determined scattering coefficient S11(iω) and the complex permittivity.
Abstract: A theoretical and experimental analysis of a simple lumped element model representing multiple reflection time domain spectroscopy (TDS) is presented. In the frequency domain, an analytical expression is derived relating the experimentally determined scattering coefficient S11(iω) and the complex permittivity. Permittivities thus determined for a number of cases in the frequency range 100 kHz to 2 GHz are shown to be a close approximation to the true permittivities in most circumstances. The conditions are discussed under which the analytical expression breaks down. The step response behavior for a Debye‐type dielectric is also calculated, leading to an improved accuracy in measuring dielectric relaxation parameters directly from time domain waveforms.
TL;DR: In this paper, the electric potential inside and outside a spherical shell, consisting of a nonlinear dielectric medium, is calculated when the shell is subjected (i) to a uniform external field, (ii) to the field of a permanent point dipole at the centre of the system, and (iii) to both these fields together.
01 Dec 1975
TL;DR: In this paper, it was shown that a slab of material having an appropriate relative permittivity can increase the antenna gain by 3-7 dB for typical cases. But the effect of dielectric material on the antenna performance was not considered.
Abstract: Structural constraints can require that the space within a radome can be filled with a rigid lightweight material, and the question arises as to whether the presence of this material can improve, rather than impair, the performance of the associated microwave antenna. Using a simplified model based on rectangular geometry, it is shown that a slab of material having an appropriate relative permittivity can increase the antenna gain by 3–7 dB for typical cases. Computations carried out using modal methods indicate that there is a pronounced periodic gain variation with slab length; this is confirmed by experiment for both planes of polarisation. The practical implementation of the enhancement technique is discussed and illustrated by typical airborne radar applications. Loss effects in the dielectric material are shown to be negligible and some simplified design data relevant to linear arrays are compiled in an Appendix.
TL;DR: In this article, the dielectric permittivity and dielectrics of four trihalogenated esters in six non-polar solvents having wide range of viscosities at 35 °C have been measured at 9.83 GHz.
Abstract: The dielectric permittivity e′ and dielectric loss e″ have been measured at 9.83 GHz for the solutions of four trihalogenated esters in six non-polar solvents having wide range of viscosities at 35 °C. The static permittivity e0 at 1 MHz and high frequency limiting permittivity e∞=nD2 have also been measured at 35 °C. The normalized plots of logτ vs. logη for these esters are linear for non-interacting solvents only. The anomalous behaviour of these solutes in other solvents has been explained in terms of solute-solvent interactions. The distribution parameter α, the free energies of activation ΔFτ, ΔFη and the dipole moment μ of these esters have also been reported.
TL;DR: In this article, a microwave bridge system with dielectric antennas of very small transverse dimensions (smaller than 10 mm) was described for measurements of the complex permittivity of slab materials.
Abstract: This paper describes the new microwave bridge system with dielectric antennas of very small transverse dimensions (smaller than 10 mm) convenient for measurements of the complex dielectric permittivity of slab materials. The system enables (i) to measure by nondestructive way the complex permittivity of dielectric and semiconducting samples the dimensions of which are comparable or smaller than the wavelength of probing microwaves, (ii) to detect the material inhomogeneities. This system was verified at the frequency 37·5 GHz. In this paper measurements of the resistivity of the Si samples are given. Results obtained are in good agreement with the theory.
12 May 1975
TL;DR: In this article, a simple non-destructive method to measure the complex permittivity of materials is described, which uses an iris terminated resonant section of waveguide in contact with the metal-backed sample.
Abstract: A simple non-destructive method to measure the complex permittivity of materials is described. It uses an iris terminated resonant section of waveguide in contact with the metal-backed sample. A numerical analysis of the structure permits one to relate the measured resonance characteristics to the sample permittivity