Complex dielectric permittivity extraction based on multilayer thin film microstrip lines

Using ground penetrating radar (GPR), we monitored a controlled low-density non-aqueous phase liquid (LNAPL) gasoline spill at a test facility at Oregon Graduate Institute, near Portland OR. The results were different from some reported for uncontrolled gasoline spills, in which the gasoline apparently blurs the contrast in dielectric permittivity that usually exists at the top of the saturated zone (SZ), so that GPR reflections from the SZ are subdued. Instead, at OGI we saw a SZ reflection almost everywhere, but this reflection was brighter (higher amplitude) under the spill. The bright spots grew and spread as the spill progressed. We explain this effect by noting that sand grains above the SZ were quite moist, so that values of relative dielectric permittivity (RDP) were relatively high there. As the spilled gasoline displaced this interstitial moisture, RDP values dropped, leading to a GPR high velocity layer and concomitant bright spots.

This study investigated the effects of water saturation and wettability on the dielectric permittivity experimentally, using four-electrode impedance measurements, and theoretically, using models that account for the electrical double layer polarization. Complex impedance measurements, performed on Berea sandstone and on Ottawa-sand packs in the frequency range 10 Hz to 1 MHz, indicated a linearly varying relative dielectric permittivity with water saturations above 50%. The rate of change of the relative dielectric permittivity with saturation decreased as the frequency increased. The relative dielectric permittivity of water-wet samples was higher than that of the oil-wet samples at all water saturations. The difference was more pronounced as the saturation increased. The relative change was approximately 60% at a water saturation of 100%. To confirm these experimental observations, this study conducted simulations of rock wettability changes using a generalized Maxwell-Wagner model by varying the amount of ionic surface charge of rocks. In general oil-wetting agents react with the formation matrix by connecting their positively charged tails to the negatively charged silica surfaces, lowering the surface charge density. Simulations showed that there was about an order of magnitude difference in the relative dielectric permittivity as the rock surface charge changed by an order of magnitude. Both simulations and experimental results showed a trend of significant increase in the relative dielectric permittivity as the rock conditions changed from oil-wet to water-wet.

The effective techniques for remediation of sites polluted by dense non-aqueous phase liquids (DNAPLs) remains a challenge. Among the various technical monitoring methods, there is an increasing interest in studying the geophysical characteristics of contaminated soils, as indicators of the progress in clean-up programs. This work sought to investigate the variation of the electrical complex resistivity and the relative permittivity by analyzing the results obtained from spectral induced polarization (SIP) and time domain reflectometry (TDR). Different series of measurements during drainage and imbibition of DNAPLs in porous media were done to validate the clean-up process on sites polluted by DNAPLs. Therefore, a methodology based on laboratory work was designed and carried out to study the electrical complex resistivity (both in magnitude and phase) in the frequency range 0.183 Hz to 20 kHz, and the relative dielectric permittivity at 70 MHz. The experiments were done on small 1D cells. In these cells, glass beads were used as a porous medium. Two different fluid couples, i.e., coal tar (CT)/water and canola oil (CO)/salty ethanol (SE), were used to produce two-phase flow. Our findings highlight that due to the high resistivity of CO and CT, an increase in water saturation led to decrease in amplitude and phase. Saturation change of SE had the same effect on resistivity but no relationship was found for phase and saturation for the mixture CO and SE. It is also showed that the complex resistivity and relative permittivity measurements were compatible with generalized Archie's law and complete complex refractive index method (CRIM) model as two empirical models for defining the correlation between the electrical resistivity, relative permittivity, and saturation of each phase in the multiphase porous medium.

This paper comprises the details about the synthesis, thermal and sporadic investigations on the nano composites. For thermal analysis, the synthesized nano composite samples are subjected to Thermo gravitometric Analysis and Differential Scanning Calorimetry tests. Whereas breakdown tests, tracking test and dielectric breakdown tests are done through galvanic investigation. The effects of fillers of various concentrations in the range of 1%, 2% and 3% of their total volume subject to different frequency in particular from 1 kHz and 10 kHz for various components. The result shows the propitious behavior of polymer nano composites. The relative permittivity and loss tangent values are reduced radically in relation with frequency. The galvanic investigation of samples indicated the promising characteristics of tracking erosion test and electrical tests for various nano composites.

We report the microwave dielectric properties of BaTiO3 thin films fabricated via aerosol deposition, which is capable of applying functional ceramic films to Si-based semiconductor fabrication at room temperature. As the starting powder, BaTiO3 powder with an average particle size of 300 nm afforded a dense thin film with a thickness of 500 nm as well as a smooth interface with the Pt/Ti/SiO2/Si substrate. In comparison, the interface roughness of BaTiO3 thin film was degraded (>100 nm) when BaTiO3 powder with an average particle size of 450 nm was used as the starting powder, owing to the excessive impact energy during film growth. Metal-insulator–metal capacitors were realized on a Si wafer via electron beam evaporation and inductively coupled plasma etching in order to determine the relative permittivity, loss tangent, and current-voltage characteristics. The average values of the relative dielectric permittivity and loss tangent of the BaTiO3 thin film were 78 and 0.03, respectively, in the frequency range of 1–6 GHz.

Herein, we have reported the dielectric properties of single phase monoclinic double perovskite oxide of Sr2YbSbO6 having lattice parameter a=5.79 Å, b=5.79 Å, c=8.19 Å and β = 90.136° with grain size ranging between 0.5 to 2.4 µm. The sample has been synthesized by solid state ceramic method. We have performed the impedence spectroscopic study of the sample in the frequency range of 40 Hz to 5 MHz at various temperatures. The relaxation in the sample is polydispersive in nature and obeys the Cole-Cole model. The values of dielectric permittivity and loss tangent at room temperature are 117.94 and 0.18 respectively. The temperature variation of dc conductivity follows the Arrhenius Law with activation energy 0.2 eV and the conduction mechanism of the sample is governed by p-type polaron hopping. Due to its high dielectric permittivity and low loss tangent the sample can be fruitfully utilized for the fabrication of radio frequency devices.

This paper implements the spectral domain approach (SDA) to study the impacts from the thin metal ground upon dispersive propagation behaviors of interconnects. Three multilayer transmission structures, the thin-film microstrip line (TFMSL), metal-insulator-metal-insulator (MIMI) line, and inverted embedded microstrip (IEM) line, are analyzed with the focus on different metallization thicknesses.

The rapid expansion of wireless technology for commercial purposes, notably mobile telephony, has created a demand for low cost, high quality, fabrication processes and materials capable of use for microwave work. In this paper a thick-film process is described which not only meets the current requirements for wireless technology, but has been shown to offer outstanding potential for advanced integrated structures operating at higher microwave frequencies, into the mm-wave band. In addition, the paper addresses the key issues of material characterisation at microwave frequencies and describes some new techniques for obtaining accurate data on relative permittivity and loss tangent of thin dielectrics. Using this technique, measurements have been made on a new low loss low temperature co-fired ceramic (LTCC) material and results are reported. Measurements have also been made to establish the principal electrical properties of the material, namely dielectric loss, dielectric permittivity and line loss. The key measured data are: (i) very low loss tangent, 10/sup -4/ over the frequency range 8-12 GHz, (ii) consistent values of 3.9 for the dielectric relative permittivity, (iii) low line loss to at least 40 GHz, and (iv) low dispersion. Experimental work has also been carried out to compare the relative performance of etched and printed thick-film lines, using a range of substrates, including LTCC materials, over a wide range of frequencies. In particular, measured data on 50 ohm microstrip lines fabricated on alumina using the new thick-film gold technology gave line loss values varying from 0.005 dB/mm at 2 GHz to 0.033 dB/mm at 40 GHz, which is a further indication of the performance that is obtainable from the technology.

When we speak about moisture measurement in grain using capacitive sensors we face with different values of dielectric permittivity for different grain types in dehydrated state, what causes a method error that can be named ‘type uncertainty’. That problem is even more significant, because different varieties of the same grain have different values of dielectric permittivity, which depend from geographical origin, processing conditions etc. These situations can be hardly predicted automatically and type uncertainty can be compensated only in separate situations with the help of preliminary calibration. The main task of the research is to decrease the type uncertainty value by developing new method of moisture measurement with testing influences on the substance under research. To estimate the relevant level of testing influences a group of different materials with 2, 2,5, 3 and 3,5 dielectric permittivity values was taken for 0, 10, 20 and 30% of moisture content. It was suggested to apply two additive and two multiplicative testing influences on a substance under research. This was enough to build a system of equations, which solvation would give us a possibility to get almost linear static function of grain moisture meter and calculate initial moisture content of a substance. During the process of experimental researches nominal moisture content values 0%, 10%, 20% and 30% were reproduced by certain types of grain with different dielectric permittivity values: pearl barley (ɛ = 3,68); poppy (ɛ = 3,56); millet (ɛ = 3,17); pea (ɛ = 2,97); wheat cereals (ɛ = 2,55). Experimental setup for measuring moisture content was assembled using the substitution method to provide good accuracy for the conditions of capacitance measurement in substances with significant dielectric losses. Obtained experimental results helped to estimate the value of related full scale error, equal to γ = 1.7%, what corresponds the restrictions of OIML R59.KeywordsMoisture measurementGrainCapacitive sensorType uncertainty method errorTesting influenceRelated full scale error

Computer modeling of the dielectric properties of the cucurbit [7]uril (CB[7]) cavity  based on the Onsager-Liptay model was carried out by analyzing the solvatochromic shift of the absorption spectrum of 1- (3ammoniumpropyl) -4 - [(E) -2- (3,4-dimethoxyphenyl) ethynyl]pyridinium upon the formation of the inclusion complex with CB[7] in a water solution. The CB[7] cavity was considered as a polar environment into which the dye chromophore is placed. Positions of the maxima of the dye absorption spectra were measured experimentally in the following solvents: methanol, ethanol, i-propanol, n-butanol and water with known dielectric and optical properties. These values were used for parametrization of the Onsager-Liptay equation. Quantum-chemical calculations were used to determine molecular structures, dipole moments of the ground and excited states, and polarizability of the dye.  Theoretical value of the effective dielectric permittivity of the cavity is in good agreement with the literature data derived by another method. Also, we investigated the preferential solvation effect of pyridinium-N-phenolate betaine (organic dye) taken as a molecular probe in two binary solvents (water-BuOH and water-BuNH2) in concentration range 0-100%. The spectral solvatochromic shift in the dye's solvation shell and the environment's dielectric permittivity were linked using the aforementioned Onsager-Liptay model. It was demonstrated that the second component of the binary solvent in water solution greatly depletes the dye's solvation shell. Both the water-BuOH and water-BuNH2 solvents exhibit this property. The water-BuNH2 solvent scenario exhibits a higher absolute spectral shift than the second case. However, in the case of water-BuOH, the relative depletion is greater. Thus, we propose a new method for investigation the dielectric constant both in bulk liquids and in very small liquid volumes. The method's unique potential lies in the creation of nanoprobe devices that may be used to test the dielectric constant of small objects and nano-regions and to adjust the instantaneous solvent concentration in evaporating sessile droplets of binary solvent in various zones of the droplet.

Wireless Power Transmission (WPT) has been discussed as early as since 1900 year, however, has only developed intensively from 1973 to recently. In WPT system, one can wirelessly transmit a high power beam (a microwave or a laser beam) from a point to another point or from Geostationary Earth Orbit (GEO) to the Earth surface. For the WPT, getting the highest collection efficiency often is among the most desirable requirements. The collection efficiency of a wireless information system and that of the WPT could be determined by using the Free Space Path Loss models or the Friis transmission equation under idealized conditions and by using Goubau parameter (τ) with the value in the range of 1.5 –2.5, respectively. Besides, the collection efficiencies of both the wireless information system and WPT system could also calculated by using the solution of the mathematical energy flux equations but this method is particularly challenging as its mathematical expression strongly depends on the Earth atmosphere layers' the relative dielectric permittivity (e r ), the relative magnetic permeability (μ r ) and the refractive index (n) by altitude. This paper briefly presents 1D model of WPT, discusses some main features of the energy transfer environment and then offers a numerical estimation of the refractive index (n rn ) in the non-ionized region and the relative permittivity (e rn ) by altitude in both the non-ionized region from 0–90 km and the ionized region from 100 km –1000 km based on the published Pedersen and Field-aligned conductivities.

Deterioration of concrete due to the alkali–silica reaction (ASR) involves a reaction between alkaline ions in the cement pore solution and non-crystalline silica found in many aggregates. The product of reaction is a porous hydrophilic ASR gel, which causes expansion and cracking of concrete structure. Currently, there is no reliable method for non-destructive evaluation of ASR. We have investigated the feasibility of using relative dielectric permittivity obtained from X-band microwave backscattering of concrete. Advantages of this method of concrete evaluation are that measurements are non-contact and one-sided, and the approach is scalable to arbitrary-size concrete structures. The exploratory study was performed using an unrestrained set of accelerated ASR concrete prism specimens developed according to the ASTM1293 standard. One set of specimens contained no entrained air, while another set was contained entrained air. The specimens were removed from the environmental chamber at different times during a year-long study to create a set of different ASR maturity specimens. Strain measurements were performed on all specimens. Strain data both air entrained and non-air entrained sets were shown to be in close agreement with Larive model of isothermal unrestrained ASR expansion with similar fitting parameters. Relative dielectric permittivity of concrete specimens was correlated with strain data. Both sets show correlation between dielectric permittivity and strain, with stronger linear correlation observed for the air-entrained specimens. Development of such correlation would enable estimating expansion of actual concrete structures from microwave backscattering measurements, which could be used for risk stratification to guide and minimize coring.

Estimation of soil moisture of a high Andean wetland ecosystem (Bofedal) with geo-radar data and In-Situ measurements, Ayacucho - Peru

In this paper, a 28GHz CMOS frequency doubler with TFMS (thin film microstrip line) has been introduced in order to experimentally study the possibility of millimeter wave CMOS devices based on TFMS. The present doubler shows 2dB conversion loss and approximately 12dB suppression to fundamental frequency. The result shows that the CMOS technology compatible TFMS are promising on the design of millimeter-wave CMOS devices.

The objective of this research was to determine if a relationship could be found between dielectric strength and other properties of electrical insulating materials in the medium of liquid nitrogen on an empirical basis by using variables predicted by basic theory. A simple equation of the form E=A+Blog (rhov/xir tandelta) to predict the dielectric strength of a solid insulating material in liquid nitrogen medium has been proposed. The equation requires the values of volume resistivity (rhov), relative permittivity (xir) and loss tangent (tandelta) in the medium of liquid nitrogen, which may be obtained easily by low voltage non-destructive measurements. The values of electric strength calculated using this equation for Crepe paper, Kraft paper, varnished paper, pressboard, presspahn, mica, bakelite and asbestos are quite in agreement with the experimentally measured values. It is expected that the equations obtained will help the designers as a handy tool for quick estimation of breakdown strength of solid dielectrics dipped in liquid nitrogen.