Showing papers on "Dielectric published in 1981"
TL;DR: In this paper, a theory for dielectric response of water-saturated sedimentary rocks based on a realistic model of the pore space is developed, where each grain is envisioned to be coated with water.
Abstract: We develop a theory for dielectric response of water‐saturated rocks based on a realistic model of the pore space. The absence of a percolation threshold manifest in Archie’s law, porecasts, electron‐micrographs, and general theories of formation of detrital sedimentary rocks indicates that the pore spaces within such rocks remain interconnected to very low values of the porosity ϕ. In the simplest geometric model for which the conducting paths remain interconnected, each grain is envisioned to be coated with water. The dielectric constant of the assembly of water‐coated grains is obtained by a self‐consistent effective medium theory. In the dc limit, this gives Maxwell’s relation for conductivity σ of the rock σ=2σwϕ/(3-ϕ), where σw is the conductivity of water. In order to include the local environmental effects around a grain, a self‐similar model is generated by envisioning that each rock grain itself is coated with a skin made of other coated spheres; the coating at each level consists of other coate...
945 citations
Book•
01 Jan 1981
TL;DR: In this article, the authors proposed a tunneling model based on the Vibrational Density of States of Amorphous Semiconductors (VDS) and three-pulse electric echo.
Abstract: 1. Introduction.- 1.1 Historical Background.- 1.2 Tunneling States.- 1.2.1 Energy Levels.- 1.2.2 Transition Probabilities and Relaxation Times.- 1.3 Organization of the Book.- References.- 2. The Vibrational Density of States of Amorphous Semiconductors.- 2.1 The Vibrational Density of States.- 2.2 Experimental Techniques.- 2.3 The Theoretical Problem.- 2.4 Brute Force Theory.- 2.4.1 Turning the Handle.- 2.4.2 Some Results of Brute Force.- 2.5 More Refined Approaches.- 2.5.1 Analytical Ideas.- 2.5.2 The Bethe Lattice.- 2.5.3 Indirect Numerical Methods.- 2.6 The Incorporation of Matrix Elements.- 2.7 Can One Derive Structural Information from g(?)?.- 2.8 A Less Myopic View of the Field.- References.- 3. Low Temperature Specific Heat of Glasses.- 3.1 Review of the Experimental Situation.- 3.2 Comparison with Theoretical Models.- 3.2.1 The Tunneling Model.- 3.2.2 The Cellular Model.- 3.3 Summary and Outlook.- References.- 4. The Thermal Expansion of Glasses.- 4.1 Theoretical Background.- 4.2 The High Temperature Expansion of Vitreous Silica.- 4.3 The Low Temperature Expansion of Glasses.- 4.3.1 Experimental Results.- 4.3.2 Discussion.- References.- 5. Thermal Conductivity.- 5.1 Thermal Transport in Crystalline Materials.- 5.2 Thermal Transport in Amorphous Materials.- 5.2.1 The Phonon Mean Free Path.- 5.2.2 Phonon Scattering Mechanisms.- 5.2.3 Summary.- 5.3 Probing the Localized Excitations.- 5.4 Synopsis.- References.- 6. Acoustic and Dielectric Properties of Glasses at Low Temperatures.- 6.1 General Comments.- 6.2 Acoustic and Dielectric Properties Above 10 K.- 6.2.1 Absorption.- 6.2.2 Sound Velocity and Dielectric Constant.- 6.3 Acoustic and Dielectric Properties Below 10 K.- 6.3.1 Acoustic and Dielectric Absorption.- a) Relaxation Effects.- b) Resonant Interaction.- 6.3.2 Sound Velocity and Dielectric Constant.- 6.3.3 Acoustic Dielectric "Cross"-Experiments.- 6.4 Theoretical Description of the Acoustic and Dielectric Properties by Two-Level Systems.- 6.4.1 Dynamical Properties of Two-Level Systems.- 6.4.2 Absorption Due to a Distribution of Two-Level Systems.- 6.4.3 Variation of Sound Velocity and Dielectric Constant.- 6.5 Comparispn Between Theory and Experiment.- 6.6 Microscopic Description: Tunneling Model.- 6.7 Summary.- References.- 7. Relaxation Times of Tunneling Systems in Glasses.- 7.1 Background.- 7.2 Resonance Dynamics of Two-Level Systems.- 7.2.1 Tunneling Model.- 7.2.2 Longitudinal Relaxation Time T1.- a) One-Phonon Relaxation.- b) Conduction Electron Relaxation.- 7.2.3 Transverse Relaxation Time T'2.- 7.2.4 Spontaneous Echo Decay.- 7.2.5 Stimulated Echo Decay.- 7.3 Experiments Measuring Relaxation Times.- 7.3.1 Acoustic Saturation.- 7.3.2 Saturation Recovery.- 7.3.3 Linewidth.- 7.3.4 Two-Pulse Phonon Echo.- 7.3.5 Two-Pulse Electric Echo.- 7.3.6 Three-Pulse Phonon Echo.- 7.3.7 Three-Pulse Electric Echo.- 7.4 Critical Assessment of Data.- 7.4.1 T1 Results.- a) Three-Pulse Echoes.- b) Saturation Recovery.- c) Distribution of Decay Times.- 7.4.2 T'2 Results.- a) Two-Pulse Echoes.- b) Linewidth.- 7.5 Conclusions.- References.- 8. Low Frequency Raman Scattering in Glasses.- 8.1 Introductory Comments.- 8.2 Vibrational Raman Spectrum of First Order.- 8.2.1 Experimental Results.- 8.2.2 Theory of Low-Frequency Spectrum.- a) Continuum Theory.- b) Bond Polarizabil ity Model.- 8.3 Quasielastic Spectrum.- 8.3.1 Experimental Results.- 8.3.2 Theory.- a) Physical Origin of the Quasielastic Scattering.- b) Relation Between Raman Scattering and Ultrasonic Absorption.- c) Defect Model.- 8.4 Conclusion.- References.- Additional References with Titles.- Subject and Material Index.
739 citations
TL;DR: In this article, the optical properties of small dielectric spheroids with or without adsorbed molecules are studied theoretically and expressions for the absorption line shapes, the radiative and nonradiative decay rates, and quantum yields are derived.
Abstract: Optical properties of small dielectric spheroids with or without adsorbed molecules are studied theoretically. Expressions for the absorption line shapes, the radiative and nonradiative decay rates, and quantum yields are derived. In the case of a molecule near a spheroid the magnitudes differ dramatically from the corresponding case of a molecule near a plane.
686 citations
TL;DR: In this article, a wide ranging critical analysis of the existing wealth of data shows that the dielectric loss obeys power-law dependences on frequencies, both below and above any loss peaks that may be present.
Abstract: The frequency dependence of the dielectric response of solids shows an apparently bewildering variety of patterns, virtually none of which corresponds to the classical Debye behaviour. However, a wide ranging critical analysis of the existing wealth of data shows that the dielectric loss obeys power-law dependences on frequencies, both below and above any loss peaks that may be present. This corresponds to power-law dependences on time under step-function excitation and it applies completely generally regardless of the detailed physical and chemical nature of the materials in question and also applies equally to dipoles, ions and hopping electrons as the polarizing species. Moreover, the power-law responses persist down to the lowest temperatures in the milliKelvin range, thus proving the importance of non-thermal transitions. The power laws are characterized by exponents in the range ± 1 and they cover as special cases the complete range of the observed types of response, from virtually frequency-independent “flat” losses often seen in low-loss materials, through various forms of asymmetric loss peaks to strongly dispersive behaviour in which both the real and the imaginary components of the susceptibility vary almost inversely with frequency. The “universality” of the power law strongly suggests the dominance in all materials of a common mechanism of dielectric relaxation and this is found in many-body interactions which provide a model capable of explaining the totality of the observed responses of solids, including both the frequency- and the temperature-dependence. In this interpretation, the classical one-particle Debye law represents but a singularity in a more general behaviour and is usually overshadowed by the new many-body mechanisms.
487 citations
TL;DR: In this paper, a fitting fitting formula for the dielectric screening function of the degenerate electron liquids at metallic and lower densities was proposed, which accurately reproduces the recent Monte Carlo results as well as those of the microscopic calculations and satisfies the selfconsistency conditions in the compressibility sum rule and the short-range correlation.
Abstract: We propose a fitting formula for the dielectric screening function of the degenerate electron liquids at metallic and lower densities which accurately reproduces the recent Monte Carlo results as well as those of the microscopic calculations and which satisfies the self-consistency conditions in the compressibility sum rule and the short-range correlation.
424 citations
TL;DR: A review of the physical properties of polyvinylidenefluoride (PVDF) with particular emphasis on its piezoelectric activity is given and the applications of this material are discussed as discussed by the authors.
Abstract: A review of the physical properties of polyvinylidenefluoride (PVDF) with particular emphasis on its piezoelectric activity is given and the applications of this material are discussed. PVDF is a semicrystalline polymer whose crystalline domains appear in four different forms. These forms may be interconverted by the application of heat, electrical fields, and pressure. Thermal poling or corona poling will orient the molecular dipoles in the crystalline parts and thus yield a permanent polarization. This polarization causes, by means of differences in the dielectric and elastic properties of the amorphous and crystalline parts, the piezoelectricity of PVDF. The piezoelectric constant d31 reaches values of about 35 pC/N at room temperature. At decreasing temperatures a drop of d31 and d33 is observed. Compared to other piezoelectric materials, PVDF has such unique properties as flexibility, ruggedness, availability as thin films, and low acoustic impedance, but a somewhat smaller electromechanical coupling factor. Applications of PVDF are in transducers for audiofrequency, ultrasonic, underwater, and electromechanical use and in pyroelectric and optical devices.
383 citations
TL;DR: In this article, a nonradiative dielectric waveguide is proposed in which dielectic strips are sandwiched between two parallel metal plates separated by a distance smaller than half a wavelength.
Abstract: A nonradiative dielectric waveguide is proposed in which dielectic strips are sandwiched between two parallel metal plates separated by a distance smaller than half a wavelength. Though the structure is substantially the same as that of the H-guide, it is based on a quite different principle of operation. This dielectric guide is particularly applicable in millimeter-wave integrated circuits, since it is not only small in size, but also allows bends and junctions to be incorporated into the circuits with very little radiation and interference. A design diagram is given. Losses and coupling coefficients of the strips are calculated, as well. Some basic circuit components, such as 90° and 180° bends and T-junctions, made of polystyrene strips, are measured to confirm their usefulness in millimeter-wave integrated circuits.
373 citations
TL;DR: In this article, the existence range of a homogeneous phase ZrxTiySnzO4 with x+y+z=2 was investigated and the unusual variation of the lattice parameters with the Sn content was discussed and the range of compositions suitable for dielectric resonators was defined.
278 citations
Patent•
23 Feb 1981TL;DR: In this paper, an electric field having a spatial intensity distribution according to an image signal is applied to a liquid crystal at a spatial period, so that a spatially phase-modulated phase diffraction grating is formed in the liquid crystal layer.
Abstract: A liquid crystal light valve projection type image display apparatus comprises an electro-optic element and a Schlieren optical system. The electro-optic element has a liquid crystal layer having a dielectric and optical anisotropy. An electric field having a spatial intensity distribution according to an image signal is applied to said liquid crystal at a spatial period, so that a spatially phase-modulated phase diffraction grating is formed in the liquid crystal layer. Thus, a projected image in enlarged form is obtained. The fact that the electric field with a spatial period is applied to the liquid crystal leads to a constant light diffraction angle, and the modulation of the diffraction light intensity in the applied electric field enables an image corresponding to the input image signal to be projected at high light utilization.
259 citations
TL;DR: In this article, a singularity in the dielectric constant of a random metal-insulator composite below the percolation threshold is reported, where the composite sample consists of small silver particles randomly dispersed throughout a KCl matrix.
Abstract: Measurements are reported of a singularity in the dielectric constant of a random metal-insulator composite below the percolation threshold. The composite sample consists of small silver particles randomly dispersed throughout a KCl matrix. The dielectric constant is found to obey a scaling relation with a critical exponent of $s=0.73\ifmmode\pm\else\textpm\fi{}0.07$.
259 citations
TL;DR: Strong evidence supporting the van de Hulst dielectric surface-wave model for these resonances is presented and use of resonances for high precision measurement of sphere size and sphere distortion, index of refraction, temperature, and vapor pressure is discussed.
Abstract: Use of the wavelength and size dependence of light scattering from optically levitated liquid drops is demonstrated as a sensitive means of detecting optical resonances of dielectric spheres. High resolution spectra are presented of the radiation pressure, far- and near-field backscatter, and 90 degrees scatter. Excellent agreement is found between experimental spectra and high resolution Mie calculations of Chylek et al. Strong evidence supporting the van de Hulst dielectric surface-wave model for these resonances is presented. Use of resonances for high precision measurement of sphere size and sphere distortion, index of refraction, temperature, and vapor pressure is discussed.
TL;DR: In this article, the authors present a complete blbliography to English language publications on dielectric resonators and present several examples of oscillator applications, as well as a tutorial for new 2-, 4-, and 6GHz bandpass filters.
Abstract: Dielectric resonators are being used in microwave filters and oscillators now that high-dielectric-constant, high-Q, temperature-stable ceramics have been developed. This paper reviews dielectric resonators with emphasis on applications, contains tutorial material, deseribes new 2-, 4-, and 6GHz bandpass filters, and presents several examples of oscillator applications. A complete blbliography to English language publications on dielectric resonators is included.
TL;DR: In this article, the largest electrocaloric effect (26°K) was measured for coarse grain material in the PZST system, in the vicinity of the Curie point.
Abstract: When an electric field is applied to a dielectric material under adiabatic conditions there is a resultant change in temperature, a phenomenon known as the electrocaloric effect Compositions in the Pb(Zr,Sn,Ti)O3 system (PZST) have several phases of nearly equal free energy, allowing antiferroelectric (AFE) to ferroelectric (FE) and paraelectric (PE) to ferroelectric (FE) transitions to occur Data are presented for electrocaloric measurements on AFE materials in the vicinity of the Curie point The effect of microstructure is reported, and experimental values are related to dielectric properties through thermodynamic relations Culmination of this work resulted in the largest electrocaloric effect (26°K) measured to date for coarse grain material in the PZST system
TL;DR: In this article, it is shown that within the present limit of experimental error, the simple Debye function is appropriate to describe the relaxational behaviour of water at microwave frequencies, however, a discrepancy between the values predicted by extrapolation of the relaxation function and the measured quantities is found.
Abstract: Complex permittivity values of water measured in this laboratory and also in a recent programme of interlaboratory measurements are reported and combined with results from the literature. Various relaxation spectral functions are considered as potential analytical representation of the extensive sets of data. It is shown that - within the present limit of experimental error - the simple Debye function is appropriate to describe the relaxational behaviour of water at microwave frequencies. In the far infrared, however, a discrepancy between the values predicted by extrapolation of the relaxation function and the measured quantities is found. The parameters of the Debye relaxation function as obtained by a nonlinear regression analysis are presented for thirteen temperatures and are briefly discussed.
TL;DR: It is shown that the dielectric tube leaky waveguide can be bent with a small bending radius compared with a metallic hollow waveguide when the guide material is appropriately selected.
Abstract: A general method is presented of evaluating bending losses in hollow-core waveguides; analytic expressions are obtained for metallic hollow, dielectric hollow, and tube leaky waveguides on the basis of the 2-D slab waveguide model. Numerical examples are given for waveguides made of different kinds of metals, oxide, and dielectric materials at 10.6 μm. It is shown that the dielectric tube leaky waveguide can be bent with a small bending radius compared with a metallic hollow waveguide when the guide material is appropriately selected.
TL;DR: The dielectric permittivity and conductivity of various canine tumor and normal tissues, and single excised muscle fibers from the giant barnacle, at frequencies from 10 MHz to 18 GHz are summarized, with emphasis on the mechanisms thai are responsible for the dielectrics of the tissues.
Abstract: We summarize the dielectric permittivity and conductivity of various canine tumor and normal tissues, and single excised muscle fibers from the giant barnacle, at frequencies from 10 MHz to 18 GHz, with emphasis on the mechanisms thai are responsible for the dielectric properties of the tissues. We discuss the variation in the dielectric properties with tissue water content and provide simple empirical formulas to allow the estimation of the dielectric properties of other soft tissues on the basis of the net tissue water content. From these considerations, we consider the possible variation in dielectric properties of living tissue in situ, with those of the excised tissue, and of tumor vs. normal tissues.
TL;DR: In this article, the spatial distribution of the electric field within a dielectric sample is shown to be obtainable unambiguously from the time dependence of the opencircuit voltage or short-circuit current during the propagation of a stress wave across the sample.
Abstract: The spatial distribution of the electric field within a dielectric sample is shown to be obtainable unambiguously from the time dependence of the open-circuit voltage or short-circuit current during the propagation of a stress wave across the sample. Experiments in which the pressure wave is generated by the impact of a pulsed laser beam on a metal target bonded to the dielectric plate under investigation have led to the first straightforward visualization of electric field distributions in solid dielectrics.
TL;DR: In this paper, the dielectric premittivities of chalcogenide compounds are explained by means of a model of a hopping process over a potential barrier between localized sites, and the theory shows, in agreement with the experimental results, that ϵ ′' = Aω m, where m is a function of temperature.
Abstract: The frequency (2 × 10 4 −2 × 10 7 Hz) and temperature (250–600 K) dependence of the imaginary part of the permittivity, ϵ′', of As 2 Se 3 and Tl 2 SnSe 8.61 is explained within a theoretical model. The dielectric premittivities of these compounds are correctly explained by means of a model of a hopping process over a potential barrier between localized sites. We have found that the glassy system of chalcogenide can exist in the form of dipoles. The theory shows, in agreement with the experimental results, that ϵ ′' = Aω m , where m is a function of temperature.
TL;DR: The phase transition in a copolymer of 55% vinylidene fluoride and 45% trifluoroethylene near 70°C has been investigated by measuring the temperature dependence of fundamental properties as mentioned in this paper.
Abstract: The phase transition in a copolymer of 55% vinylidene fluoride and 45% trifluoroethylene near 70°C has been investigated by measuring the temperature dependence of fundamental properties. The remanent polarization disappeared near 70°C. The dielectric relaxation strength showed a peak indicating an anomaly and the dielectric relaxation time showed a critical slowing down phenomenon. A change in crystal lattice spacing associated with remanent strain and an anomalous specific heat were observed. These results are consistent with a ferroelectric phase transition. Comparison is made between observation and prediction by phenomenological and simple dipolar theories for a order-disorder type transition.
TL;DR: In this paper, the authors used the Foldy approximation to find an equation for the mean field and derived an effective permittivity for the scattering medium from this equation, from which the correlation of the scattered field was found by employing the distorted Born approximation, i.e., particles embedded in the effective medium are assumed to be single scatterers.
Abstract: Electromagnetic backscattering from a sparse distribution of lossy dielectric particles having random orientation and position is studied. The paper begins by using the Foldy approximation to find an equation for the mean field. From this equation, an effective permittivity for the scattering medium is obtained. The correlation of the scattered field is found by employing the distorted Born approximation, i.e., particles embedded in the effective medium are assumed to be single scatterers. The above method is then used to find the backscattering coefficients from a leaf canopy. The leaf canopy is modeled by a half space of dielectric discs that are small in comparison to a wavelength. Numerical results show that the depolarized cross section is a sensitive function of leaf inclination angle statistics.
TL;DR: In this paper, the ferroelectric properties of polyvinylidene fluoride and trifluoroethylene copolymer were studied and it was found that the phase transition was accompanied by an expansion of the crystal lattice.
Abstract: The ferroelectric properties of vinylidene fluoride‐trifluoroethylene copolymer were studied. The infrared absorption spectra and x‐ray diffraction patterns of the melt‐crystallized film suggested the similar crystalline form to the polar form I of polyvinylidene fluoride. It was found that the ferroelectric‐to‐paraelectric phase transition occurred at 70 °C and was the first order in the melt‐crystallized copolymer film by studying the dielectric constant, piezoelectric constant, D‐E hysteresis loop, and DSC measurement. The Curie constant was 2200 K. The phase transition was accompanied by the expansion of the crystal lattice.
TL;DR: The amplitude of the orientational dielectric dispersion of impure polycrystalline ice has been measured at temperatures down to 133 K in an attempt to find evidence for an ordering transition as mentioned in this paper.
Abstract: The amplitude of the orientational dielectric dispersion of impure polycrystalline ice Ih has been measured at temperatures down to 133 K in an attempt to find evidence for an ordering transition. The Curie–Weiss temperature is 6.2±1.7 K and so, within the experimental precision, there is no significant evidence that the molecular orientations become more correlated than the ice rules require. From the most recent results on polycrystalline ice, the Curie–Weiss temperature is 15±∼11 K. As this temperature is far below the lowest experimental temperatures, the evidence for an ordering temperature is not firm. The activation energy for dielectric relaxation in the impure ice is 25.5 kJ mol−1 at high temperature and increases at low temperatures. The low activation energy is caused by impurities that generate orientational defects in about the maximum number physically possible, and is mainly the activation energy for diffusion of the defects. At lower temperatures, the impurities produce fewer defects and t...
Patent•
26 Oct 1981TL;DR: An H-plane sectoral horn antenna is loaded with low-loss dielectric insertsn alternative embodiments so as to reduce beamwidth, increase axial gain and to achieve non-mechanical beam scanning as discussed by the authors.
Abstract: An H-plane sectoral horn antenna is loaded with low-loss dielectric insertsn alternative embodiments so as to reduce beamwidth, increase axial gain and to achieve non-mechanical beam scanning. In one embodiment, the antenna is transversely loaded with a multi-layer dielectric array containing an air gap of critical thickness between four dielectric strips. In another embodiment, the antenna is longitudinally and symmetrically loaded with wedge-shaped dielectric strips separated by a critical air gap between the dielectric and antenna walls.
TL;DR: In this article, the shape of axisymmetric dielectric drop in a uniform electric field is computed numerically and the problem is formulated as a nonlinear integro-differential system of equations.
Abstract: The shape of an axisymmetric dielectric drop in a uniform electric field is computed numerically. The problem is formulated as a nonlinear integro‐differential system of equations. They are discretized and the resulting algebraic system is solved by Newton’s method. The results show that when the dielectric constant e is larger than a critical value ec, the drop develops two obtuse‐angled conical points at its ends for a certain field strength. For e
TL;DR: The dielectric function epsilon identical with ePSilon(1) + iepsilon(2) has been determined for Al (2)O(3) films prepared by electron beam evaporation, in the 5-50-microm wavelength range.
Abstract: The dielectric function ∊ = ∊1 + i∊2 has been determined for Al2O3 films prepared by electron beam evaporation, in the 5–50-μm wavelength range. The data were extracted from spectrophotometric recordings of transmittance and reflectance by use of a novel technique. Supplementary measurements were made of the refractive index for visible and near-infrared wavelengths and of the dielectric constant at 1 MHz. Kramers-Kronig analysis was employed to check the consistency of our results for ∊1 and ∊2.
TL;DR: In this article, the dielectric and elastic properties of cyano-substituted nematic liquid crystals are investigated in terms of molecular properties and molecular association, and the results are discussed in terms both molecular and molecular associations.
Abstract: The dielectric and elastic properties of cyano‐substituted nematic liquid crystals are investigated. The results are discussed in terms of molecular properties and molecular association.
TL;DR: In this paper, the authors derived the angular distribution of light emitted into the half-spaces 1 and 2, and derived the dipole radiation patterns for the case in which any numbers of loss-free or absorbing, dielectric or metallic thin films are present between the loss-less layer 0 of arbitrary thickness containing the source and the halfspaces 0 and 2.
Abstract: The emission of light by sources, e.g., by luminescent centers, located in a thin nonabsorbing dielectric layer 0 between two half-spaces 1 and 2 is investigated theoretically. It is assumed that the light is emitted in electric or magnetic dipole transitions. But the theory is given in such a form that it can easily be extended to electric and magnetic quadrupole and higher-order multipole transitions. The electromagnetic boundary-value problem is solved rigorously for sources in layers 0 of arbitrary thickness. The radiation patterns, i.e., the angular distributions of light emitted into the half-spaces 1 and 2, are calculated. The theory takes into account the following effects that strongly influence the radiation patterns: (1) the wide-angle interferences that are a consequence of the coherence of the plane waves emitted into different directions, (2) the multiple-beam interferences that result from the multiple reflections of the plane waves between the interfaces 0/1 and 0/2, and (3) that evanescent waves present in the near field of the source radiate into media 1 and/or 2 if these media are denser than layer 0. This emission process is influenced by evanescent-wave effects analogous to the wide-angle interferences and the multiple-beam interferences of the plane waves. The limiting case of extremely thin layers 0 with optical thickness much smaller than the wavelength is also treated. Explicit analytical expressions are presented for the dipole radiation patterns in this case. Furthermore, the theory is generalized for sources in plane-stratified-layer systems. The dipole radiation patterns are derived for the case in which any numbers of loss-free or absorbing, dielectric or metallic thin films are present between the loss-free layer 0 of arbitrary thickness containing the source and the half-spaces 1 and 2.
TL;DR: In this article, the real part of the dielectric constant e′ of rocks at low frequencies can be anomalously high due to the presence of a small concentration η of high aspect ratio particles.
Abstract: We show that the real part of the dielectric constant e′ of rocks at low frequencies can be anomalously high due to the presence of a small concentration η of high aspect ratio particles. For oblate spheroidal grains (a≪b=c) with depolarization factor along symmetry (-a) axis, Ls≅1-δ, δ=πa/2b, the static value of the dielectric constant of rock es and dc conductivity σ(0) are given for (1)δ ηbyσ(0)≅σR(1-η/δ), es≅ηe′m/δ2. Here e′m is the dielectric constant of the grain; σR is the dc conductivity of the host rock. Case (1) corresponds to the well known Maxwell‐Wagner effect with es diverging as η → 0, and σ(0)→0. Case (2) gives a novel result that es may diverge for δ>η≫δ2, with a nonvanishing σ(0). Case (2) is applied to explain frequency and salinity dependences and the giant values (∼104) of the dielectric constant of conducting sedimentary rocks. For η∼10-4, δ∼10-3, e′m=10, we find es∼1000, which is large compared to e′m or the dielectric constant of water e′w(∼80).
TL;DR: In this article, an exact field theory solution for the cylindrical TM/sub 010/ cavity with a coaxial lossy dielectric cylinder is given, and the error in the calculated field solutions is estimated to be less than 1 percent of the true values.
Abstract: An exact field theory solution for the cylindrical TM/sub 010/ cavity with a coaxial lossy dielectric cylinder is given. The error in the calculated field solutions is estimated to be less than 1 percent of the true values. Correction for the cavity holes used to introduce the sample is taken into account. The exact solution shows that the real part of the permittivity (epsilon') is a complex function of both the frequency shift and the change in the loaded Q-factor (Q/sub L/). On the other hand the imaginary part (epsilon") is nearly proportional to delta(1/Q/sub L/) and it has different slopes for varying frequencies. By means of active cavity techniques already reported, experimental measurements on epslion' and epsilon" taken at 2.2 GHz on a number of materials (water, teflon, n-proponal, methanol, etc.) agree with published data within 1 percent even when rising large samples.