Showing papers on "Relative permittivity published in 1988"

Cross polarization characteristics of rectangular patch antennas

Abstract: The authors present detailed results showing the variation of a quantity characterizing the crosspolarization for different feed positions, substrate thickness, and relative permittivity. The results are given both when the excitation is at the resonant frequency of the TM/sub 01/ mode and when the excitation is at the resonant frequency of the TM/sub 10/ mode. >

Dielectric properties of supercooled glycerol-water solutions

Abstract: Dielectric properties of glycerol-water mixtures from 5 mHz to 2 MHz are studied over the temperature range 140 to 350 K. Dielectric relaxation time can be fitted according to the new free-volume percolation model of Cohen and Grest (1981, 1984). Static permittivity varies linearly with reciprocal temperature. Suitable extrapolations to zero glycerol concentration allowed the calculation of the dielectric relaxation time and the static permittivity of supercooled water with the relationship xi =-36.7+33980/T behavior is in good agreement with the random network model proposed by Sceats and Rice (1982). >

Precise Measurement Method for Complex Permittivity of Microwave Dielectric Substrate

Abstract: A new technique for the measurement of the complex permittivity of dielectrie substrates using a dielectric resonator is reported. This method is a non-contact measurement using two dielectric resonators which support TE mode. This paper describes some examples of measurements.

An improved MFIE formulation for TE-wave scattering from lossy, inhomogeneous dielectric cylinders

Abstract: A method-of-moments formulation involving the magnetic-field integral equation (MFIE) is presented for the analysis of nonhomogeneous electric (TE) source. The approach involves the use of triangular subdomain cells, a piecewise linear expansion for the total magnetic field, and point matching at the nodal points of the triangular-cell model. Results for internal fields and radar cross section are presented and shown to be stable and convergent, even for dielectrics characterized by a large-magnitude complex relative permittivity. It is noted that the complementary problem of TM-wave scattering from ferrite cylinders characterized by a permeability function can be treated using the dual to the approach presented. >

Soft mode behaviour of a room temperature ferroelectric liquid crystal

Abstract: The complex dielectric permittivity was studied in the frequency region 100 Hz ÷ 100 kHz in the vicinity of the SA→ SC* phase transition temperature Tc = 32°C for benzoic acid 4-octyloxy 4–|(2-methyl butyloxy) carbonyl | phenylester. The d.c. electric field of the intensity E = 4 kV/cm was used to unwind the helicoidal structure in S C* phase, therefore the contribution to ϵ from the Goldstone mode was eliminated. It was found that at 100 Hz the temperature dependence of the soft node contribution had the form of the Curie-Weiss law in both SA and SC* phases. At higher frequencies the maximum of ϵ at TC is lowered and at frequencies 10 ÷ 40 kHz a minimum appears. This behaviour was explained by the temperature dependence of the soft mode relaxation frequency fS which was evaluated by fitting the complex permittivity data to the Debye relaxation formula. It was established that fS depended linearly on temperature in SA as well as in SC* phases with a minimum of 1 kHz at TC.

The dielectric properties of rabbit tissue, pure water and various liquids suitable for tissue phantoms at 35 GHz.

Abstract: Newly developed microwave apparatus was used to measure the complex permittivity of some rabbit tissues and water over the temperature range 20-37 degrees C. Various liquid mixtures which might be suitable as phantom tissue equivalents at 35 GHz were also considered. Some of the measured tissue data were compared with previous lower frequency data and it was concluded that the observed behaviour was not anomalous.

Diurnal And Seasonal Wriations In The Microwave Dielectric Constant Of Selected Trees

Abstract: In situ dielectric probes were used to monitor the L-band dielectric constant of several tree species as a function of time. Observation sequences included both diurnal and seasonal sampling strategies applied to arrays of coaxial probes inserted to various depths in the bole of the tree. The magnitude of the dielectric constant is not uniform throughout the bole, but forms concentric shells related to the wet and dry density of the media. Furthermore, for certain tree varieties and at certain times of year, the observed diurnal change in relative permittivity can be up to an order of magnitude. In addition, the relative permittivity can be radially asymmetric at certain times of day. The implications of these dielectric properties with respect to microwave scattering by the tree trunks are discussed.

Dielectric constant of binary mixtures of liquids

Abstract: Experimental results on the dielectric properties of silicone fluid and water-free methanol are reported. The results are compared with the results obtained by calculations using several available formulas for calculating the dielectric constants of liquid mixtures. A new formula for the calculation of the dielectric constant based on the fundamental properties of the individual components is suggested. >

Semiconductor substrate and manufacture thereof

Abstract: PURPOSE: To obtain a semiconductor substrate, whose apparent relative permittivity is low and whose operating speed is fast, by a method wherein a multitude of pieces of voids are distributed in the interior of an insulating film formed on a noninsulating semiconductor supporting substrate. CONSTITUTION: An Si substrate 1 is oxidized to form an SiO 2 on its surface, this film 2 is selectively etched to form stripped grooves and an SiO 2 film 12 holding voids is obtained. Then, one more Si substrate 1 for forming a semiconductor thin film is superposed on the surface of the film 12 and an annealing is performed in an nitrogen-containing atmosphere. When an electrostatic pressure is applied to this annealing, the adhesion of the substrate 1 to the substrate 1 is more improved. After both substrates 1 are adhered to each other, the upper substrate 1 is polished to form into a thin film and an Si thin film 11 is formed. Accordingly, the apparent relative permittivity of this substrate is reduced because a multitude of pieces of the voids are distributed in the interior of the insulating film. Thereby, a semiconductor substrate, whose strain capacitance is small and whose operating speed is fast, can be manufactured. COPYRIGHT: (C)1989,JPO&Japio

Improved Cavity Resonance Method For Nondestructive Measurement Of Complex Permittivity Of Dielectric Plate

Abstract: An improved cavity resonance method is proposed to measure the complex permittivity of dielectric plate sample nondestructively. A plate sample is clamped by two halves, into which a cavity is cut at the center. The effect of the fringing field is accurately calculated by the Ritz-Galerkin method.

Technique for extracting dielectric permittivity from data obscured by electrode polarization

Abstract: A technique was developed by which the dipole orientation component can be extracted from the total measured permittivity in the presence of electrode polarization. The static dielectric permittivity and relaxation times for fluids containing mobile ions can thus be determined unambiguously. The approach is based on the use of nonlinear regression to fit an established model for the frequency dependence of permittivity to the measured data. >

Tubular dielectric waveguides and resonators

Abstract: The effect of the central hole in tubular dielectric waveguides is quantitatively displayed in eigenvalue diagrams for the five lowest modes of propagation. The measurement of the relative dielectric constant for tubular dielectric resonators is described. The tuning mechanism which utilizes a dielectric rod protruding into the tubular TM/sub 01/ resonator is analyzed by the finite integrated method. >

Odd-Even Effects in the Dielectric Properties of Nematics 4-(Trans-4′-N-Alkylcyclohexyl)Isothiocyanatobenzenes

Abstract: The anisotropy of the static electric permittivity and conductivity for the homologous series of nematics: 4-(trans-4′-n-alkylcyclohexyl)isothiocyanato-benzenes (n-CHBT) for n = 3–10 have been measured. It is shown that the odd-even effect in the dielectric anisotropy Ac is related to the perpendicular component of electric permittivity. The odd-even effect is found in n-CHBT for both the anisotropy in the conductivity and the activation energy for ionic movement.

Proof of the existence of the lifshitz point in NH4HSeO4

Abstract: The effect of the do electric biasing field on the dielectric permittivity and birefringence of NH4HSeO4 (AHSe) single crystals between 240 and 270K has been investigated. It has been confirmed that under the influence of the field EL≥ 14kV/cm the IC phase disappears.

Longitudinal and transverse current distributions on coupled microstrip lines

Abstract: The normalized longitudinal and transverse current distributions on coupled microstrip lines are obtained for even and odd modes by using the charge conservation formula and the charge distributions calculated by a Green's function technique. Their dependence on the shape ratios w/h and s/h and on the relative permittivity epsilon * of the substrate is shown. >

On the calculation of the dielectric properties of suspensions

Abstract: The dielectric properties of suspensions are usually calculated from the quasi-static solution of the Laplace equation for the potential around a single particle in the continuous phase. The results are only straightforward for the static conductivity and for the high frequency permittivity, since these expressions only involve the potentials which are in phase with the applied field. The static permittivity and the high frequency conductivity, are much more difficult to evaluate, since they strongly depend on the limiting behaviour of the out of phase terms, which actually vanish in these two limits. Using arguments based on the stored energy and on the dissipated power, it is shown how the expressions for the static permittivity and the high frequency conductivity, can be calculated using only the in phase terms of the potential. The results are much easier to derive than using the classical procedure, and they contribute to a better understanding of the meaning of the relaxation amplitudes. A ...

An accurate method for permittivity and loss tangent measurements of low loss dielectric using TE/sub 01 delta / dielectric resonators

Abstract: Accurate methods of permittivity and loss tangent measurements of low loss dielectrics using TE/sub 01 delta / mode dielectric resonators are discussed To reduce influence of conductor losses on the Q-factor of the resonant system the dielectric specimen is placed far from metal walls but conductor losses are taken into account by means of a rigorous methods of analysis It is shown that using these methods accuracy of loss tangent measurements can be improved 2-3 times in comparison with the classical Courtney method< >

Investigation of soil as a lossy dielectric

Abstract: The authors present results of measurements and laboratory tests performed with several soil samples to investigate their dielectric and conduction characteristics in the predominant range of frequencies for transient phenomena in electric power systems. The effects of such factors as humidity and frequency variation on these characteristics are considered, and an analysis of the obtained data is presented. At constant frequency, an increase of humidity results in an increase of permittivity and a decrease of resistivity and affects the value of loss tangent. When frequency is increased, the permittivity and resistivity decrease significantly. The loss tangent presents a maximum at intermediate frequency values. It is remarkable that at higher frequencies this parameter shows values not much different from those at lower frequencies. >

Polar properties induced in NaNbO3 by Mn dopant

Abstract: An additional maximum in the dielectric permittivity was obsrved in the samples of sodium niobate doped with manganese. Electric hysteresis loop was detected when the concentration of the manganese dopant exceeded its critical value.

Millimeter Wave Measurement Of Complex Permittivity By Improved Dielectric Disk Resonator Method

Abstract: A resonance method using a dielectric disk resonator, consisting of a plate sample clamped between two conductor cylinders, is described for measuring the temperature dependence of the complex permittivity in the millimeter wave region An alumina substrate is measured at 36 GHz by this method

Ultra-low dielectric constant porous silica thick films for high-speed IC packaging

Abstract: Interconnect systems which are required in high-speed GaAs digital ICs use stripline techniques for signal traces which must be deposited over very low dielectric constant substrates. Materials with relative dielectric constant k less than 3 and having low-loss tangent up to microwave frequencies are required for ceramic materials. Such values are impossible to achieve in single-phase ceramic monoliths; composite approaches are necessary. A technique for preparing porous silica films 1-10- mu m thick is presented. The dielectric constant of these films is in the range of 2.4 to 2.8 with a loss tangent less than 0.005 at 1 kHz. >

On the Feasibility of Millimeter Wave Directional Filters using Dielectric Resonators

Abstract: This paper is concerned with the feasibility of millimeter wave directional filters using high permittivity (? r= 36) cylindrical dielectric resonators. Measured filter responses at about 35 GHz are presented.

Silent discharge generating device and gas treatment

Abstract: PURPOSE:To provide a large silent discharge generating space, gas permeable and stabilized, by setting structure for permeating gas with a number of air- permeable small hole spaces constituted of dielectric materials showing relative permittivity of given range between a couple of electrodes. CONSTITUTION:A net-shaped ground electrode 8 and an electric field applicator 9 formed with conductive materials are provided in an insulated device case 5, and globular particles 11 constituted of dielectric materials of the given relative permittivity such as barium titanate and the like are filled between said both electrodes 8 and 9 to constitute a structure 10 for permeating gas. When alternating voltage is applied from an electric source 14 to the electric field applicator 9, external electric field is applied to the whole of globular particles 11, and silent discharge is generated in slightly formed spaces between globular particles 11. For instance, the air to be treated containing NO flows from the upstream side 6 of the gas 5 to the downstream side 7 to mix NH3 and water content into the air to be treated. The air to be treated reacts during passing the area of generating silent discharge and turns into NH4NO3 and the like which are adhered to the surface of globular particles 11 and collected.

Mode analysis of a dielectric-loaded Raman-type free-electron laser

Abstract: The Raman-type free-electron laser consists of a relativistic electron beam contained in a dielectric-induced parallel plate waveguide and an array of permanent magnets for the wiggler. Under the influence of the periodic magnetostatic field, the coupling between the scattered electromagnetic wave of the TE mode (positive-energy wave) and the electron plasma wave of the TM mode (negative-energy wave) is investigated in detail. The following results are obtained. First, when a dielectric sheet is loaded on the waveguide, the maximum growth rate and the oscillation frequency can be greater than those for the vacuum Raman-type free-electron laser. Second, by choosing proper values for the relative permittivity of the dielectric sheet and the ratio of the beam guide, the beam energy can be greatly lowered without degrading the oscillation characteristics. Third, the growth rate decays exponentially with the oscillation frequency kept almost constant as the beam-dielectric gap increases. >

Anomalous high permittivity in salty ice-a new dielectric phenomenon

Abstract: The dielectric properties of salty ice including some one-valence alkali halides have been studied in the temperature range from -5 degrees C to -60 degrees C. It has been discovered that the salty ice has a very high permittivity, which can be over ten times higher than that for ordinary ice at the same conditions. The permittivity can be over 1000 and depends on the saline ionic concentration and radius of ion in salty ice. The authors conclude that the anomalous high-permittivity phenomenon is produced by the additional polarization effect in salty ice. The mechanism is due to thermionic polarization by the action of a high effective electric field. >

Equations for Complex Relative Permittivity of Saline Water

Abstract: Equations hare been presented to calculate the complex relative permittivity of saline water as a function of salt content and temperature of water. The results obtained from these equations show good agreement with the published measured data.

Treating device for microwave plasma

Abstract: PURPOSE:To form uniform plasma by fitting a dielectric plate consisting of a dielectric which is large in relative dielectric constant and small in dielectric loss to the inner wall of the terminal part of a waveguide or the terminal part and the inner wall of the part adjacent to the terminal part. CONSTITUTION:Output electric power of a microwave oscillator 1 is led to a reaction vessel 3 made of quartz via a waveguide 2. Specified kind of gas is introduced into the reaction vessel 3 via a gas feed pipe 6 and discharged at constant flow rate through an exhaust pipe 7. Thereby the inside of the reaction vessel 3 is maintained at constant pressure and the introduced gas is made to plasma by means of microwave electric power and etching processing or depositing treatment of a thin film is performed on the surface of a sample 4 placed on a sample base 5. The cross-section of the waveguide 2 is a rectangular shape or a circular shape and its end is housed in the reaction vessel 3 and enlarged into a tapered shape to reduce the reflection of microwave electric power.