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The advancement of both electronics and instrumentation technology has fostered the development of multi-physics platforms that can probe the earth’s subsurface. Remote, non-destructive testing techniques have led to the increased deployment of electromagnetic waves in sensor technology. Electromagnetic wave techniques are reliable and have the capacity to sense materials and associated properties with minimal perturbation. However, meticulous data analyses and mathematical derivations reveal inconsistencies in some formulations. Thus, revisiting the fundamental physics that underlies both electrical impedance experimental setups and electromagnetic properties are paramount. This study aims to unravel inherent limitations in the understanding of the relationships between electromagnetic and non-electromagnetic properties that are relevant to the characterization of fluids in porous media. These correlations pervade porosity, permeability, specific surface, pore size distribution, tortuosity, fluid discrimination, diffusion coefficient, degree of saturation, viscosity, temperature, phase transformation, miscibility, salinity, and the presence of impurities. The focus is on the assessment of liquids, soils, rocks, and colloids using broad spectral frequency complex permittivity, conductivity, magnetic permeability, and nuclear magnetic resonance relaxometry. Broadband electrical properties measurement for saturated porous media can provide multiple physical phenomena: Ohmic conduction, electrode polarizations, Maxwell-Wagner spatial polarizations, rotational, and segmental polarizations. Liquids dominate the electromagnetic signatures in porous media as dry minerals are inherently non-polar and non-conductive. Results reveal that voltage drops due to the discontinuity of charge-carrier at the electrode-electrolyte interface named electrode polarization inherently affect the low-frequency electrical measurements both in two- and four-probe configurations. Rotational polarizations that occur in MHz-GHz ranges are defined by the electrical dipole moment and effective molecular volume. Both viscosity and effective molecular volume govern the NMR transverse relaxation time. An engineered soil suspension with ferromagnetic inclusions exhibits excellent characteristics for drilling fluid application. Overall, the study highlights the complementary nature of conductivity, permittivity, and NMR relaxation for the advanced characterization of fluid saturated geomaterials.

This study focus on trying to understand what factors regarding bumper materials and coatings affect the radar transparency at 77 GHz. Dielectric spectroscopy was done at 25 unique samples, consisting of various plastic substrates, primers, basecoats and clearcoats with the Free-spaced method in the 60-90 GHz region. The plastic substrate consisted of Polypropylene-blend with different fillers such as talc, carbon black and metal flakes. The basecoats analyzed were 2 solid factory coatings (one black and one white), 5 factory coating containing different effect pigments such as metal flakes, Xiralic, and Mica, 1 factory PVD coating and 2 aftermarket basecoats. All samples were provided by a Volvo Cars’ supplier, however, some samples were repainted with the aftermarket coatings. The complex permittivites were calculated for each PP-blend and coating from the curve fitting of the measured S-parameters from the Free-spaced method. Material analysis such as thickness measurements of the plastic substrate and coatings, ATR-FTIR spectroscopy, TGA and DSC were done at all plastic substrates. The plastic substrates and the coating were also observed in optical microscope and in SEM. The calculated permittivities were compared with the results from the material analysis and correlations between increased metal content in the basecoat and higher real permittivity were found. Some relationship between the size of the metal flakes and the radar transparency could also be observed. Further, correlations between higher real permittivity with higher concentration of talc and carbon black were detected. MATLAB was used to provide an example for optimization of the plastic thickness for a given basecoat in order to have minimal reflection at 77 GHz.

Clay, quartz and feldspar are widely available in Uganda. The location and properties of various clay deposits are reported in the literature, but little is reported on feldspar and quartz deposits. In this work an extended literature on ceramics and porcelains in particular, is documented. Samples from two deposits of feldspar and two deposits of quartz are characterised and found to possess requisite properties for making porcelain insulators. Sample porcelain bodies are made from materials collected from selected deposits using different mixing proportions of clay, feldspar and quartz. Their properties in relation to workability, firing temperature, dielectric and bending strengths are studied. It is found that a mixture consisting of 30% Mutaka kaolin, 15% Mukono ball clay, 30% Mutaka feldspar and 25% Lido beach flint yields a body with highest mechanical strength (72MPa) and dielectric strength (19kV/mm) when fired at 1250°C. The strength (both mechanical and dielectric) is found to decrease with increasing firing temperature. At high firing temperatures, the undissolved quartz in the body decreased, the glass content increases and pores are formed. Mullite content on the other hand does not change at temperatures above 1200°C but there are significant differences in the morphologies of the mullite crystals in the samples. Optimum mechanical and electrical properties are found at maximum virtification and a microstructure showing small closely packed mullite needles. / QC 20101122

A higher degree of system level integration can be achieved by integrating the passive components into semiconductor devices, which seem to be an enabling technology for portable communication and modern electronic devices. Greater functionality, higher performance and increase in reliability can be achieved by miniaturizing and reducing the number of components in integrated circuits. The functional potential of small electronic devices can be enormously increased by implementing the embedded capacitors, resistors and inductors. This would free up surface real estate allowing either a smaller footprint or more silicon devices to be placed on the same sized substrate. This thesis focuses on the effect of deposition temperature and post deposition annealing (PDA) in different gas ambient on the electrical properties of sputter deposited ferroelectric Barium Strontium Titanate (Ba0.5St0.5) TiO3 thin film capacitors. Approximately 2000A of Barium Strontium Titanate (BST) thin film was deposited at different substrate temperatures (400,450,500 and 550[degrees]C) on cleaned silicon substrates. These BST films were then annealed separately in 100% N2, 100% O2 and 10% O2 + 90% N2 at 575[degrees]C in sputtering machine (PVD anneal) and a three zone annealing Lindberg furnace. The objective of this thesis was to compare the effect of PDA on the electrical properties of BST films deposited at different substrate temperatures between PVD annealing and furnace annealing. For this work, tantalum thin film was used as top and bottom electrode to fabricate the capacitors. BST thin film capacitors were fabricated and characterized for leakage current and dielectric breakdown. Roughness study on pre and post annealed BST films were done using optical profilometer. The capacitors were tested using HP impedance analyzer in the frequency range from 10Hz through 1 MHz. From the experiments, 100% O2 annealed furnace annealed BST thin film seem to have better dielectric constant, higher breakdown voltage and nominal capacitance density.

A modified CVD reactor was designed with a deposition chamber capable of accommodating 8" wafers, with the capacity to remotely pyrolyze two different precursors. The design was based on a previous working reactor, with the most notable improvements being a showerhead design for more even delivery of gaseous precursor and a separate heating control of the substrate holder and deposition chamber walls. The performance of the reactor was analyzed by testing the pressure gradients within and the thickness uniformity of films deposited on 8" wafers. The reactor exhibited a linear pressure gradient within, and the thickness uniformity was excellent, with a slight increase in thickness towards inlet of the showerhead. The thickness difference between the maximum and minimum thickness on an 8" wafer was 14%. Films of polyparaxylylene (PPXN), polychloroparaxylylene (PPXC), SiO₂, and PPXC/SiO₂ were deposited, with deposition rates and indices of refraction comparable to those obtained on the old reactor design. A full factorial study was performed to determine the effect of the substrate temperature, the sublimation temperature, and the pyrolysis temperature on the deposition rates of PPXC. It was determined that the substrate temperature has the greatest effect, with about 50% contribution, and deposition rates increased with decreasing substrate temperature. The sublimation temperature contributed 25%, with increasing sublimation rates leading to higher deposition rates. The pyrolysis contributes very little, with about 2%, and the variance ratio did not fall within a 90% confidence level. A low dielectric constant polymer, poly(tetrafluoro-p-xylylene) (VT-4), was synthesized by chemical vapor deposition from 4,5,7,8,12,13,15,16-octafluoro-[2.2]-paracyclophane (DVT-4). The main motivation was to find a cheaper alternative to poly( alpha, alpha , alpha ', alpha '-tetrafluoro-p-xylylene) (AF-4) with similar properties. The dielectric constant of VT-4 was measured as 2.42 at 1 MHz, and the in-plane and out-of-plane indices of refraction were 1.61 and 1.47 at 630 nm. The large negative birefringence suggests a low out-of-plane dielectric constant, which is desired for interlayer dielectrics. The VT-4 polymer was found to be stable at 460 °C by thermogravimetric analysis (TGA). Polymer/Siloxane nanocomposites were studied as an alternate path to a polymer/silica composite. This study showed that incorporation of a four-ringed liquid siloxane precursor into the parylene PPXC is not feasible. A solid precursor cube-like molecule, vinyl-T8, was incorporated with ease. Pyrolysis of vinyl-T8 at different temperatures revealed complex behavior, with the formation of polymerized vinyl-T8 (through free radical addition at the vinyl groups) as well as silica-like structures forming above 500 °C as a result of the breaking up of the cage structure of vinyl-T8. Codepositions of PPXC and vinyl-T8 were then examined as a possible path towards a polymer/silica nanocomposite. At deposition temperatures below 5 °C, precipitation of excess vinyl-T8 into cubic micron-sized crystals occurred. As this was undesirable, studies were continued at higher deposition temperatures. A Taguchi orthogonal array was set up to study the effect of the sublimation temperatures of the two precursors as well as the pyrolysis temperature and the substrate temperature on the deposition rate, the index of refraction and the weight loss after a 500 °C anneal. The deposition rate depended mostly on the sublimation temperature of the PPXC and the substrate temperature. The lowest index of refraction (and thus the lowest dielectric constant) was obtained with the lowest sublimation temperatures of 134 °C for PPXC and 195 °C for vinyl-T8 and a pyrolysis temperature of 200 °C. Each of the factors was found to have an effect on the index of refraction, with the sublimation temperature of vinyl-T8 having the most influence. The films degraded at 500 °C, indicating that post-deposition annealing of the films did not lead to a conversion of the vinyl-T8 to a SiO₂-like structure (which would be stable at that temperature). X-ray diffraction spectra of the films revealed peaks which were not present for any of the vinyl-T8 films or characteristic of PPXC. Therefore, some type of interaction between the two components occurred and affected the morphology, most likely the formation of a block copolymer. Thus, though polymer/silica films were not attained, the resulting composites had comparable properties with higher deposition rates and a cleaner process. / Master of Science

No / Two Cylindrical Dielectric Resonators DR asymmetrically placed on a thin dielectric substrate and fed by a single rectangular slot for wideband wireless applications are presented. Optimized design procedures were applied within a well-known electromagnetic solver to achieve the improved elements dimensions of the antenna geometry. The simulated and measured results show that the proposed DRA can achieve 29% relative bandwidth at 10 dB return loss covering the spectrum range from 9.62 GHz to 12.9 GHz with a maximum gain of 8 dB.

No / A small dielectric resonator antenna has been designed for ultra wideband (UWB) communication system applications. The antenna element is a rectangular low permittivity ceramic block, with a dielectric constant of 9.4, and the modified T-shaped feed network includes a 50 ohm microstrip line to achieve strong coupling, and some bandwidth enhancement. The antenna performance is simulated and measured over a frequency band extending from 3100 MHz to 5500 MHz; the impedance bandwidth over this interval is 55.8% with VSWR <; 2, making the antenna suitable for UWB applications.

Yes / In this paper, a 2.45 GHz band microwave sensor design is introduced to be utilized for the dielectric constant determination of ethanol-water solutions. The introduced microwave sensor is composed of two symmetrically positioned, directly coupled inter-connected split-ring resonators with a circular ring-shaped detection area in the middle region, into which a small amount of ethanol-water solution is dropped. The fabricated prototype of the microwave sensor has a total component size of 12 mm x 30 mm on Rogers RO4003 substrate. The sensor measurement performance is numerically evaluated and experimentally validated in good agreement. The introduced microwave sensor has the structural design novelty of possessing the main detection region in a form of a circular hollow where a disposable 3D printed fluid cup can be accommodated for multiple uses. The introduced microwave sensor has technical feasibility to be used as an ingredient identification device for the chemical solutions to figure out complex dielectric parameters of ethanol-water specimens with small, low-cost, reusable, easy-to-fabricate features as well as the determination of volume percentage concentration of ethanol content.