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A controlled column experiment was conducted to investigate the geophysical response of gasoline spills into the partially saturated sand column. The column was 0.61 diameter (ID) and 2 m high cylindrical polyvinyl chloride, which was packed with the Borden sand to a height of 1.95 m, flushed with CO2, saturated, and drained to a height of 0.73 m. The monitoring techniques used for this experiment was DC resistivity and time domain reflectometry (TDR) methods. The column was equipped with resistivity electrodes and TDR probes, which were placed on the column wall vertically with 3 cm intervals, on opposite sides, two monitoring wells, an injection well, a manometer, an outlet/inlet system, and a vent. A total amount of 5 liters of standard API 91-01 gasoline was added to the system in steps of 1, 2, and 2 liters to examine the geophysical response to different amounts of gasoline. Measurements were taken before and after each injection and also during subsequent fluctuation of the water table. Both monitoring techniques were able to record even the minor changes in the trend of conductivity and permittivity profiles due to the addition of the small amount of gasoline during the first spill. The conductivity and permittivity profiles obtained before lowering the water level below the original level and those obtained after the water level reached to the original level do not match, which is an indication of entrapped gasoline inside the pores. Two core samples was taken from the sand symmetrically after each water table fluctuation and analyzed for total petroleum hydrocarbon (TPH) analysis and the results were compared to the conductivity and permittivity results. The conductivity profile obtained using DC resistivity method was compared to that of obtained using TDR method. The profiles match in the saturated zone where all of the pores are connected with water and therefore electrolytic conduction is predominant. In the unsaturated zone, where there is low pore water connectivity, TDR measured conductivity values are higher than those measured using the resistivity method. Water saturation values were calculated using conductivity and permittivity values before and after each injection. Different values of saturation exponent (n) were tested for Archie’s law until an appropriate value was found which gave the best water saturation from conductivity data for clean Borden sand. Then, the water saturation obtained from permittivity values using Topp’s equations for different materials were compared to that of obtained from conductivity values using Archie’s equation. Topp’s equation for 30 µm glass beads provided the best match. Furthermore, other equations developed by other researchers were examined to obtain water saturation profiles from the permittivity values; all of them overestimate the water saturation for Borden sand. The water saturation profiles after the gasoline spills obtained using both Archie’s law and Topp’s equation do not match, perhaps because both equations were developed for three-phase (water-solid-air) systems.

A controlled column experiment was conducted to investigate the geophysical response of gasoline spills into the partially saturated sand column. The column was 0.61 diameter (ID) and 2 m high cylindrical polyvinyl chloride, which was packed with the Borden sand to a height of 1.95 m, flushed with CO2, saturated, and drained to a height of 0.73 m. The monitoring techniques used for this experiment was DC resistivity and time domain reflectometry (TDR) methods. The column was equipped with resistivity electrodes and TDR probes, which were placed on the column wall vertically with 3 cm intervals, on opposite sides, two monitoring wells, an injection well, a manometer, an outlet/inlet system, and a vent. A total amount of 5 liters of standard API 91-01 gasoline was added to the system in steps of 1, 2, and 2 liters to examine the geophysical response to different amounts of gasoline. Measurements were taken before and after each injection and also during subsequent fluctuation of the water table. Both monitoring techniques were able to record even the minor changes in the trend of conductivity and permittivity profiles due to the addition of the small amount of gasoline during the first spill. The conductivity and permittivity profiles obtained before lowering the water level below the original level and those obtained after the water level reached to the original level do not match, which is an indication of entrapped gasoline inside the pores. Two core samples was taken from the sand symmetrically after each water table fluctuation and analyzed for total petroleum hydrocarbon (TPH) analysis and the results were compared to the conductivity and permittivity results. The conductivity profile obtained using DC resistivity method was compared to that of obtained using TDR method. The profiles match in the saturated zone where all of the pores are connected with water and therefore electrolytic conduction is predominant. In the unsaturated zone, where there is low pore water connectivity, TDR measured conductivity values are higher than those measured using the resistivity method. Water saturation values were calculated using conductivity and permittivity values before and after each injection. Different values of saturation exponent (n) were tested for Archie’s law until an appropriate value was found which gave the best water saturation from conductivity data for clean Borden sand. Then, the water saturation obtained from permittivity values using Topp’s equations for different materials were compared to that of obtained from conductivity values using Archie’s equation. Topp’s equation for 30 µm glass beads provided the best match. Furthermore, other equations developed by other researchers were examined to obtain water saturation profiles from the permittivity values; all of them overestimate the water saturation for Borden sand. The water saturation profiles after the gasoline spills obtained using both Archie’s law and Topp’s equation do not match, perhaps because both equations were developed for three-phase (water-solid-air) systems.

A new model for the complex dielectric constant, ε, of aqueous ammonia (NH4OH) has been developed based on laboratory measurements in the frequency range between 2-8.5 GHz for ammonia concentrations of 0-8.5 %NH3/volume and temperatures between 277-297 K. The new model has been validated for temperatures up to 313 K, but may be consistently extrapolated up to 475 K and ammonia concentrations up to 20 %NH3/volume. The model fits 60.26 % of all laboratory measurements within 2σ uncertainty. The new model is identical to the Meissner and Wentz (2004) model of the complex dielectric constant of pure water, but it contains a correction for dissolved ammonia. A description of the experimental setups, uncertainties associated with the laboratory measurements, the model fitting process, the new model, and its application to approximating jovian cloud opacity for NASA's Juno mission to Jupiter are provided.

There are several methods for the full-wave characterization of waveguide discontinuities; Finite Element Method (FEM), Finite Difference Technique (FDT), and Method of Moments (MoM) are popular. However, these methods are not easily applied when studying the modal anatomy of a discontinuity. Other full-wave techniques are better suited. This dissertation discusses the formulation of a technique known as Generalized Transverse Resonance (GTR), which is a subset of Method of Moments. Generalized Transverse Resonance is a hybrid method combining the Transverse Resonance Method (TRM) with the Mode Matching Technique (MMT). The understanding of the generalized transverse resonance method starts with a discussion of Longitudinal Section Waves and from this derives the transverse resonance method for layered media para1lel to the wave propagation. It is shown that Maxwells equations can be represented as a mode function and voltage or current. This representation is used to reduce to the problem of merging the TRM and MMT into the GTR method by using network theory. The propagation constant is found by solving the wave equation, as an eigenvalue problem, subject to the boundary conditions. Discussed is the relative convergence phenomenon followed by the optimization strategy. Once the propagation constant is found, the cross sectional fields can be solved and from the fields the characteristic impedance is found. Theoretical data is compared to measure data to show the accuracy of the GTR method. Presented is an understanding of the propagation characteristics of a CPW transmission line in proximity with high and low loss silicon. This data will show the loss and propagation characteristics for four CPW structures using two separate silicon lids at six different heights above the transmission line. Two modes have been clearly identified and will be explained.

The composition-dependent Curie temperature and bias-dependant dielectric permittivity of Barium Strontium Titanate (BST) makes it very attractive for tunable application in the RF/Microwave regime. In this research work, the performance of BST varactors fabricated on the conventional Pt/Ti/SiO2/Si bottom electrode stack were compared with those fabricated using chemical vapor deposited Nanocrystalline Diamond (NCD) as the diffusion barrier layer instead of SiO2. The varactors fabricated on NCD films displayed much better symmetry in capacitance-voltage behavior and better overall quality factors than varactors fabricated on SiO2. The improvement in performance can be attributed to existence of stable interfaces in the devices fabricated on NCD which reduced the bottom electrode losses at high frequencies. The SiO2 based BST varactors on the other hand displayed better reliability and breakdown fields. The main purpose of this research work is to develop a robust Metal Insulator Metal (MIM) structure to achieve better all round performance of BST varactors. In the second part of this research work, the prospect of developing diamond based layered Surface Acoustic Wave (SAW) devices using Ba0.8Sr0.2TiO3 as the piezoelectric layer is investigated. Structural characterization of BST thin films deposited on Si/NCD/Pt and Si/SiO2/Ti/Pt stack were performed using X-Ray Diffraction (XRD) and Atomic Force Microscopy (AFM). Cross-sectional studies on the two stacks were performed using Scanning Electron Microscopy (SEM). X-Ray Mapping (XRM) was then done to ascertain the quality of the interfaces and to check for interdiffusion between layers. MIM structures in the Coplanar Waveguide (CPW) configuration were fabricated using conventional lithography and etching techniques for high frequency measurements. The performance of the fabricated varactors was characterized from 100 MHz to 1 GHz. For the SAW application, structural characterization of Ba0.8Sr0.2TiO3 on Chemical Vapor Deposited (CVD) diamond was done and the deposition procedure was optimized to obtain thick BST films. SAW bandpass filters and resonators were designed wherein the device geometry was varied over a wide range in order to characterize the variation in device performance with geometry. Finally interdigital capacitor structures were fabricated and used for conducting Curie temperature measurements on the deposited BST films in order to determine the operation range of the deposited BST films.

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / In this paper, a new technique utilizing a scatterer of high dielectric constant in between electrically small antennas to achieve good Direction of arrival (DOA) estimation performance is demonstrated. The phase information of the received signal at the antennas is utilized for direction estimation. The impact of the property of the scatterer on the directional sensitivity and the output signal to noise ratio (SNR) level are studied. Finally the DOA estimation accuracy is analyzed with the proposed technique under the consumption of white Gaussian noise environment.

The performance of modern high frequency components and electronic systems are often limited by the properties of the materials from which they are made. Over the past decade, there has been an increased emphasis on the development of new, high performance dielectrics for use in high frequency systems. The development of these materials requires novel broadband characterization, instrumentation, and extraction techniques, from which models can be formulated. For this project several types of dielectric sheets were characterized at terahertz (THz) frequencies using quasi-optical (free-space) techniques. These measurement systems included a Fourier Transform Spectrometer (FTS, scalar), a Time Domain Spectrometer (TDS, vector), a Scalar Network Analyzer (SNA), and a THz Vector Network Analyzer (VNA). Using these instruments the THz spectral characteristics of dielectric samples were obtained. Polarization based anisotropy was observed in many of the materials measured using vector systems. The TDS was the most informative and flexible instrument for dielectric characterization at THz frequencies. To our knowledge, this is the first such comprehensive study to be performed. Anisotropy effects within materials that do not come into play at microwave frequencies (e.g. ~10 GHz) were found, in many cases, to increase measured losses at THz frequencies by up to an order of magnitude. The frequency dependent properties obtained during the course of this study included loss tangent, permittivity (index of refraction), and dielectric constant. The results were largely consistent between all the different systems and correlated closely to manufacturer specifications over a wide frequency range (325 GHz-1.5 THz). Anisotropic behavior was observed for some of the materials. Non-destructive evaluation and testing (NDE/NDT) techniques were used throughout. A precision test fixture was developed to accomplish these measurements. Time delay, insertion loss, and S-parameters were measured directly, from which loss tangent, index of refraction, and permittivity was extracted. The test materials were low-loss dielectric slabs ranging in thickness from 1-60 mils. The substrate sheets were PTFE, fiberglass, and epoxy-ceramic composite substrates. The other group was polyethylene plastic sheets (LDPE/HDPE/UMHW) and 3D printer Photopolymers. The results were verified by using several online THz spectral databases and compared to manufacturer data sheets. Permittivity and loss of some of the test samples varied as a function of polarization angle. 0 - 90 degrees of rotation were tested (i.e., H-V, and 45 degrees polarization). Inter-molecular scattering in the composite materials raised the loss considerably. This effect was verified. Standard, well documented, material types were selected for the project for best comparison. These techniques can also be applied to analyze newer substances such as nanodielectrics.

Hydrate-bearing sediments may contribute to the availability of energy resources, affect climate change, or cause seafloor instability. The comprehensive study of hydrate-bearing sediments documented in this manuscript includes physicochemical aspects of hydrate nucleation near mineral surfaces, the validity of THF as a substitute guest molecule for the study of hydrate-bearing sediments, and the effects of hydrate formation on the electromagnetic and the mechanical properties of various soils with a wide range of specific surface. Natural marine sediments are included as part of this investigation to explore the effects of inherent fabric, salts, organic matter, and stress history on the geophysical properties of hydrate-bearing sediments. Experiments are designed to reproduce the state of effective stress in the field at the time of hydrate formation. A comprehensive set of instruments is deployed in this study, and the unprecedented development of electrical resistivity tomography for the study of hydrate formation and dissociation is also documented in detail. Results from this research have important implications for geophysical field characterization and monitoring processes such as production.

The main purpose of this dissertation was to address key issues in the design and analysis of RF/microwave filters for wireless applications. Since RF/microwave filters are one of the bulkiest parts of communication systems, their miniaturization is one of the most important technological challenges for the development of compact transceivers. In this work, novel miniaturization techniques were investigated for single-band, dual-band, ultra-wideband and tunable bandpass filters. In single-band filters, the use of cross-shaped fractals in half-mode substrate-integrated-waveguide bandpass filters resulted in a 37 percent size reduction. A compact bandpass filter that occupies an area of 0.315 mm2 is implemented in 90-nm CMOS technology for 20 GHz applications. For dual-band filters, using half-mode substrate-integrated-waveguides resulted in a filter that is six times smaller than its full-mode counterpart. For ultra-wideband filters, using slow-wave capacitively-loaded coplanar-waveguides resulted in a filter with improved stopband performance and frequency notch, while being 25 percent smaller in size. A major part of this work also dealt with the concept of 'hybrid' RF MEMS tunable filters where packaged, off-the-shelf RF MEMS switches were used to implement high-performance tunable filters using substrate-integrated-waveguide technology. These 'hybrid' filters are very easily fabricated compared to current state-of-the-art RF MEMS tunable filters because they do not require a clean-room facility. Both the full-mode and half-mode substrate-integrated waveguide tunable filters reported in this work have the best Q-factors (93 - 132 and 75 - 140, respectively) compared to any 'hybrid' RF MEMS tunable filter reported in current literature. Also, the half-mode substrate-integrated waveguide tunable filter is 2.5 times smaller than its full-mode counterpart while having similar performance. This dissertation also presented detailed analytical and simulation-based studies of nonlinear noise phenomena induced by Brownian motion in all-pole RF MEMS tunable filters. Two independent mathematical methods are proposed to calculate phase noise in RF MEMS tunable filters: (1) pole-perturbation approach, and (2) admittance-approach. These methods are compared to each other and to harmonic balance noise simulations using the CAD-model of the RF MEMS switch. To account for the switch nonlinearity in the mathematical methods, a nonlinear nodal analysis technique for tunable filters is also presented. In summary, it is shown that output signal-to-noise ratio degradation due to Brownian motion is maximum for low fractional bandwidth, high order and high quality factor RF MEMS tunable filters. Finally, a self-sustained microwave platform to detect the dielectric constant of organic liquids is presented in this dissertation. The main idea is to use a voltage- controlled negative-resistance oscillator whose frequency of oscillation varies according to the organic liquid under test. To make the system self-sustained, the oscillator is embedded in a frequency synthesizer system, which is then digitally interfaced to a computer for calculation of dielectric constant. Such a system has potential uses in a variety of applications in medicine, agriculture and pharmaceuticals.