scholarly journals Measurement of the complex dielectric constant down to helium temperatures. I. Reflection method from 1 MHz to 20 GHz using an open ended coaxial line

2000 ◽  
Vol 71 (2) ◽  
pp. 473-477 ◽  
Author(s):  
H. C. F. Martens ◽  
J. A. Reedijk ◽  
H. B. Brom
Keyword(s):  
Dielectric Constant ◽  
Coaxial Line ◽  
Complex Dielectric Constant ◽  
Reflection Method

THE COMPLEX DIELECTRIC CONSTANT OF SOLUTIONS OF TRIMETHYLPENTANE AND NITROBENZENE NEAR THE CONSOLUTE TEMPERATURE

1961 ◽  
Vol 39 (3) ◽  
pp. 526-534 ◽  
Author(s):  
B. D. Ripley ◽  
R. McIntosh
Keyword(s):  
Dielectric Constant ◽  
Phase Separation ◽  
Standing Wave ◽  
Applied Field ◽  
Coaxial Line ◽  
Dielectric Constants ◽  
Complex Dielectric Constant ◽  
Experimental Procedure ◽  
Chemical Systems ◽  
Consolute Temperature

The complex dielectric constants of three compositions of trimethylpentane and nitrobenzene have been measured as a function of temperature for a range near the consolute temperature. The frequency employed was 3300 Mc/sec. The experimental procedure involved the study of the standing wave established in a coaxial line. The chemical systems showed maxima in both the real and imaginary parts of the complex dielectric constant at temperatures above those at which phase separation occurs. The finding of Semenchenko and Azimov is thus confirmed. A discussion of the validity of applying thermodynamic formulae to dielectrics showing loss is given and some qualitative remarks are offered concerning the change of the systems as they are cooled. These remarks are based upon the effect of the applied field upon the entropy of the solutions.

A Laboratory Technique for Measuring Dielectric Properties of Core Samples at Ultrahigh Frequencies

1985 ◽  
Vol 25 (04) ◽  
pp. 502-514 ◽  
Author(s):  
Liang C. Shen
Keyword(s):  
Dielectric Constant ◽  
Rectangular Waveguide ◽  
Coaxial Line ◽  
Core Sample ◽  
Complex Dielectric Constant ◽  
Laboratory System ◽  
The Core ◽  
Core Samples ◽  
Outer Conductor ◽  
Central Conductor

Abstract This paper describes an automated laboratory system that can measure accurately the dielectric properties of core samples in the ultrahigh-frequency properties of core samples in the ultrahigh-frequency (UHF) range. The system consists of a precision coaxial-line sample holder, a network analyzer, a plotter, a printer, and a desk computer. The computer is for measurement control, data acquisition, and data analysis. A new method is developed to measure and to compensate for the error of the network analyzer system. This method uses a brass sample and does not require standard terminations. A procedure for core sample preparation is also recommended to ensure accuracy of the data. Introduction The electromagnetic propagation tool (EPT) is a relatively new wireline sonde developed by Schlumberger for detection and quantification of hydrocarbon. It is operated at 1.1 GHz, which is in the UHF band of the electromagnetic spectrum. The EPT sonde measures the dielectric constant of the formation. Because water has a much higher dielectric constant (about 80 units) than oil (about 2 units) and gas (about 1 unit), the EPT sonde can distinguish hydrocarbon-bearing zones from the water-bearing zones even when the formation water is fresh. The dielectric constant of water at UHF is not very sensitive to salinity. Consequently, EPT is particularly useful in situations where the formation water resistivity is variable or unknown, as a result, for example, of water, steam, or chemical flooding. The EPT log displays the travel time and the rate of attenuation of the electromagnetic wave in the formation. From these data, the calculated complex dielectric constant of the formation may be calculated. This complex dielectric constant is related to water saturation, Sw, by an empirical formula called the complex refractive index method (CRIM): ............................(1) where = porosity, = dielectric constant of the water in the rock, = dielectric constant of oil or gas, and = dielectric constant of the rock grain. To verify the validity of the CRIM formula given by Eq. 1, a computer-controlled laboratory system has been set up to measure the dielectric constants of saturated core samples, dry core samples, and oils. The same system is now being used for routine measurements of cores for EPT log interpretation. Measurement Techniques Two basic techniques can be used to measure the complex dielectric constant of a saline-water-saturated rock at frequencies higher than 100 MHz. The first is the coaxial-line and waveguide method, and the other is the resonant-cavity method. We describe these methods and point out their advantages and disadvantages. Fig. 1 shows the configuration of the coaxial-line and waveguide method. In Figs. 1a and 1b, we see that the core sample is machined into a circular cylinder with a circular concentric hole drilled to fit the coaxial line. The line consists of an outer conductor and an inner conductor. In Fig. 1c, we see that the core sample is machined into a rectangular column to fit into a rectangular waveguide. The latter is a rectangular metal pipe without a central conductor. pipe without a central conductor. Longitudinal slots are cut along the outer conductor of the coaxial line (Fig. 1b) or on top of the rectangular waveguide (Fig. 1c) to allow a probe to be inserted partially into the region where electromagnetic fields are present. The probe travels along the length of the structure and detects the amplitude and the phase of the electromagnetic fields present in the structure. During the measurement, an electromagnetic wave of the selected frequency is sent propagating down the line or the waveguide until it encounters the core sample. Reflection occurs so that part of the wave is absorbed, and part is reflected and travels in the reverse direction. The phase and the amplitude of the reflected wave are determined by the complex dielectric constant of the sample. The reflected wave interacts with the incident wave and creates an interference pattern called the standing wave pattern. The complex dielectric constant of the core sample can be determined from the standing wave pattern recorded by the traveling probe. This method was used by Poley et al. for sandstone samples up to 1.2 GHz. It was also used by Tam to test nine dry rocks, mainly sedimentary, in the frequency range 150 to 1000 MHz. The rectangular waveguide was used by Roberts and Von Hippel to measure a variety of materials at 5 GHz. The configuration shown in Fig. 1a was used by Rau and Wharton to measure formation samples in the frequency range 500 MHz to 1.1 GHz. This arrangement calls for placing the sample at the center, rather than at the end, of a coaxial line. The amplitudes and the phases of both the reflected and the transmitted waves are recorded and are called the scattering matrix parameters. parameters. SPEJ p. 502

THE COMPLEX DIELECTRIC CONSTANT AT LOW MICROWAVE FREQUENCIES OF ETHYL CHLORIDE ADSORBED ON POROUS VYCOR GLASS

1961 ◽  
Vol 39 (3) ◽  
pp. 425-442 ◽  
Author(s):  
J. D. McCowan ◽  
R. McIntosh
Keyword(s):  
Dielectric Constant ◽  
Coaxial Line ◽  
Ethyl Chloride ◽  
Complex Dielectric Constant ◽  
Frequency Range ◽  
Vycor Glass ◽  
Microwave Frequencies ◽  
The Real ◽  
Porous Vycor Glass ◽  
Accuracy Of Measurement

The complex dielectric constant of the system Vycor glass – ethyl chloride has been measured at three temperatures in the range +11 °C to −33 °C and in the frequency range between 500 Mc sec−1 and 4000 Mc sec−1 by the use of a coaxial line. The real and imaginary parts of the dielectric constant of the adsorbate have also been evaluated. Appreciable loss in the adsorbed matter is found for small quantities adsorbed, and loss is again detected at the highest frequencies and lowest temperatures for the matter held in multilayers or condensed in capillaries. The frequency range and accuracy of measurement were not sufficient to classify the type of loss curve, but other evidence suggests that the loss for the first quantities adsorbed will turn out to be that for rotational oscillators. In general earlier observations of this system are confirmed and extended.

Microwave Bragg structures in a half-open coaxial line

2021 ◽  
Vol 1 (1) ◽  
pp. 4-12
Author(s):  
A. R. Nasybullin ◽  
O. G. Morozov ◽  
R. V. Farkhutdinov ◽  
T. M. Ishkaev
Keyword(s):  
Dielectric Constant ◽  
Numerical Calculation ◽  
Electromagnetic Fields ◽  
Coaxial Line ◽  
Wave Impedance ◽  
Complex Dielectric Constant ◽  
Urgent Problem ◽  
Bragg Structures ◽  
Microwave Structures ◽  
Coaxial Lines

Bragg microwave structures in a coaxial line have found application as converting elements in devices for dielectric control of liquid and bulk medias. A feature of the measuring conversion of the complex dielectric constant in coaxial structures is the introduction of the substance under study into the inner space of the line. The latter circumstance imposes certain restrictions on the design of the external conductor for express control. In this regard, the consideration of half-open coaxial lines based on an external conductor in the form of longitudinal conducting rods is an urgent problem. The article proposes a method for calculating the wave impedance of a half-open coaxial line using a numerical calculation of electromagnetic fields. Based on the results of modeling Bragg microwave structures in a half-open coaxial line, recommendations are made for the construction of conversion elements based on them.

Development of a Capacitor Probe to Detect Subsurface Deterioration in Concrete

1997 ◽  
Vol 503 ◽  
Author(s):  
B. K. Diefenderfer ◽  
I. L. Al-Qadi ◽  
J. J. Yoho ◽  
S. M. Riad ◽  
A. Loulizi
Keyword(s):  
Dielectric Constant ◽  
Portland Cement ◽  
Electromagnetic Waves ◽  
Low Cost ◽  
Complex Dielectric Constant ◽  
Life Cycle Costs ◽  
Parallel Plates ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Set Up

ABSTRACTPortland cement concrete (PCC) structures deteriorate with age and need to be maintained or replaced. Early detection of deterioration in PCC (e.g., alkali-silica reaction, freeze/thaw damage, or chloride presence) can lead to significant reductions in maintenance costs. However, it is often too late to perform low-cost preventative maintenance by the time deterioration becomes evident. By developing techniques that would enable civil engineers to evaluate PCC structures and detect deterioration at early stages (without causing further damage), optimization of life-cycle costs of the constructed facility and minimization of disturbance to the facility users can be achieved.Nondestructive evaluation (NDE) methods are potentially one of the most useful techniques ever developed for assessing constructed facilities. They are noninvasive and can be performed rapidly. Portland cement concrete can be nondestructively evaluated by electrically characterizing its complex dielectric constant. The real part of the dielectric constant depicts the velocity of electromagnetic waves in PCC. The imaginary part, termed the “loss factor,” describes the conductivity of PCC and the attenuation of electromagnetic waves.Dielectric properties of PCC have been investigated in a laboratory setting using a parallel plate capacitor operating in the frequency range of 0.1 to 40.1MIHz. This capacitor set-up consists of two horizontal-parallel plates with an adjustable separation for insertion of a dielectric specimen (PCC). While useful in research, this approach is not practical for field implementation. A new capacitor probe has been developed which consists of two plates, located within the same horizontal plane, for placement upon the specimen to be tested. Preliminary results show that this technique is feasible and results are promising; further testing and evaluation is currently underway.

MEASUREMENT OF THE COMPLEX DIELECTRIC CONSTANT OF LIQUIDS AT CENTIMETER AND MILLIMETER WAVELENGTHS

1957 ◽  
Vol 35 (9) ◽  
pp. 995-1003 ◽  
Author(s):  
A. G. Mungall ◽  
John Hart
Keyword(s):  
Dielectric Constant ◽  
Methyl Alcohol ◽  
Free Space ◽  
Normal Incidence ◽  
Complex Dielectric Constant ◽  
Families Of Curves ◽  
Millimeter Wavelengths ◽  
Centimeter Wave ◽  
Space Technique ◽  
Wave Region

The measurement of the complex dielectric constant of lossy liquids in the millimeter and centimeter wave region by a free-space technique is described. The method involves the measurement of absorption per wavelength and of reflectance at normal incidence. Families of curves are given for the relations between these two quantities and the real and imaginary parts of the complex dielectric constant. Results for ethyl and methyl alcohol at 9 and 13 mm. wavelength are compared with those obtained by waveguide techniques.

scholarly journals Characteristics of Poly(vinyl Alcohol) (PVA) Based Composites Integrated with Green Synthesized Al3+-Metal Complex: Structural, Optical, and Localized Density of State Analysis

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1316
Author(s):  
Shujahadeen B. Aziz ◽  
Muaffaq M. Nofal ◽  
Hewa O. Ghareeb ◽  
Elham M. A. Dannoun ◽  
Sarkawt A. Hussen ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Metal Complex ◽  
Band Gap ◽  
Optical Band Gap ◽  
Complex Dielectric Constant ◽  
Poly Vinyl Alcohol ◽  
Optical Parameters ◽  
Dispersion Energy ◽  
Casting Technique

The influence of dispersing Al-metal complex on the optical properties of PVA was investigated using UV–visible spectroscopy. Polymer composite films with various Al3+-complex amounts in the PVA matrix were arranged by solution casting technique by means of distilled water as a widespread solvent. The formation of Al3+-metal complex was verified through Ultraviolet–visible (UV-Vis) and Fourier-transform infrared spectroscopy (FTIR) examinations. The addition of Al-complex into the polymer matrix led to the recovery of the optical parameters such as dielectric constant (εr and εi) and refractive index (n). The variations of real and imaginary parts of complex dielectric constant as a function of photon wavelength were studied to calculate localized charge density values (N/m*), high-frequency dielectric constant, relaxation time, optical mobility, optical resistivity, and plasma angular frequency (ωp) of electrons. In proportion with Al3+-complex content, the N/m* values were amplified from 3.68 × 1055 kg−1 m−3 to 109 × 1055 kg−1 m−3. The study of optical parameters may find applications within optical instrument manufacturing. The optical band gap was determined from Tauc’s equation, and the type of electronic transition was specified. A remarkable drop in the optical band gap was observed. The dispersion of static refractive index (no) of the prepared composites was analyzed using the theoretical Wemple–DiDomenico single oscillator model. The average oscillator energy (Eo) and oscillator dispersion energy (Ed) parameters were estimated.

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