As seismic waves travel through the earth, the visco-elasticity of the earth's medium will cause energy dissipation and waveform distortion. This phenomenon is referred to as seismic absorption or attenuation. The absorptive property of a medium can be described by a quality factor Q, which determines the energy decay and a velocity dispersion relationship. Four new ideas have been developed in this thesis to deal with the estimation and application of seismic absorption. By assuming that the amplitude spectrum of a seismic wavelet may be modeled by that of a Ricker wavelet, an analytical relation has been derived to estimate a quality factor from the seismic data peak frequency variation with time. This relation plays a central role in quality factor estimation problems. To estimate interval Q for reservoir description, a method called reflectivity guided seismic attenuation analysis is proposed. This method first estimates peak frequencies at a common midpoint location, then correlates the peak frequency with sparsely-distributed reflectivities, and finally calculates Q values from the peak frequencies at the reflectivity locations. The peak frequency is estimated from the prestack CMP gather using peak frequency variation with offset analysis which is similar to amplitude variation with offset analysis in implementation. The estimated Q section has the same layer boundaries of the acoustic impedance or other layer properties. Therefore, the seismic attenuation property obtained with the guide of reflectivity is easy to interpret for the purpose of reservoir description. To overcome the instability problem of conventional inverse Q filtering, Q compensation is formulated as a least-squares (LS) inverse problem based on statistical theory. The matrix of forward modeling is composed of time-variant wavelets. The LS de-absorption is solved by an iterative non-parametric approach. To compensate for absorption in migrated seismic sections, a refocusing technique is developed using non-stationary multi-dimensional deconvolution. A numerical method is introduced to calculate the blurring function in layered media, and a least squares inverse scheme is used to remove the blurring effect in order to refocus the migrated image. This refocusing process can be used as an alternative to regular migration with absorption compensation.

The conventional planar micro transformers presented very low quality-factor (Q<10) and very high insertion loss (-6 ~ -10 dB) at high operation frequency since most of the microwave power is dissipated through the silicon substrate. To increase the quality-factor and reduce the insertion loss of silicon-based transformers, this dissertation presents a two-port and three-port micro transformers with suspending structure utilizing the micro-electro-mechanical systems (MEMS) technology. The proposed silicon-based transformers are constructed by two winding and suspending micro inductors. Each suspending micro inductor consists of a 0.32 &#x00B5;m-thick TaN/Ta/Cu bottom electrode, a 10 &#x00B5;m-height supporting copper vias and a 6 &#x00B5;m-thick spiral copper conducting layer. This research adopts the Taguchi method and commercial electromagnetic simulation software (Ansoft-HFSS) to optimize the dimensional specifications of the copper conducting layer. Many high frequency characteristics of the suspending micro transformers are simulated, including the inductance, the magnetic coupling factor, the quality-factor, the magnitude imbalance, the phase imbalance, the common mode rejection ratio (CMRR) and the insertion loss. In this research, the surface micromachining and electrochemical deposition techniques are used to implement the suspending micro transformers. The main fabrication steps include five photolithography and eight thin-film deposition processes. According to the simulation and measurement results from the commercial network analyzer (Agilent-E8364B) and software (Agilent-ADS), the implemented two-port transformer demonstrates a high magnetic coupling factor (0.78) and a very high quality-factor (Q=17.20) at 5.2 GHz. On the other hand, the proposed three-port transformer presents a low magnitude imbalance (-0.02 dB), a low phase imbalance (1.65¢X), a high CMRR (36.78 dB) and a very low insertion loss (-4.52 dB) under the same operation frequency. In this dissertation, a novel suspending micro transformer has been developed and characterized. The proposed micro transformer is very suitable for being used in the portable microwave communication system due to its small chip size (0.7 mm¡Ñ0.7 mm¡Ñ0.5 mm) and excellent high-frequency characterization.

Recently, the evolutions of wireless communication systems are growing rapidly to satisfy the personal communication requirements. Compact, small size, low cost, and multi-function are the major developing trends among these modern wireless communication devices. The use of ceramic materials with high permittivity can effectively reduce the sizes of microwave devices. This thesis consists of two parts: the research of microwave dielectric materials and the implementation of microstrip ceramic antennas. In the first part of the dissertation, the systematic investigations of the microstructure and microwave dielectric properties in respect of BiNbO4-based ceramics and MCAS glass-added Al2O3-TiO2 ceramics have presented. By the addition of CuO, V2O5, or CuO-V2O5 mixture, the BiNbO4 ceramics can be densified at lower sintering temperatures less than 940¢J. The excellent microwave dielectric properties are obtained as 0.5 wt% CuO or V2O5 are added as sintering aids. The exceeded additive amount or sintering temperatures will result in the appearance of abnormal grain growth and the increase of grain boundary inclusions, which will decrease the microwave dielectric properties including the quality factor (Q) and the temperature coefficient of resonant frequency (£nf). The CuO-added BiNbO4 ceramics reveal a negative £nf value and V2O5-added BiNbO4 ceramics reveal a positive one. The £nf values can be reduced to near 0 ppm/¢J by controlling the weight ratio of CuO/V2O5. Another method to reduce the £nf values to near 0 ppm/¢J is the substitution of Sm for Bi. For the (Bi1-xSmx)NbO4 ceramics, the presence of the £]-form of (Bi1-xSmx)NbO4 ceramics will affect the grain growth, density, Q¡Ñf values and £nf values, but that has no apparent effect on £`r values. On the whole, a high permittivity, an acceptable quality factor, and the temperature stable BiNbO4-based ceramic can be obtained. As for (1-x)Al2O3-xTiO2 ceramics, the addition of MCAS glass can lower the sintering temperatures of (1-x)Al2O3-xTiO2 ceramics from 1500¢J to 1300¢J. And the £nf value can be adjusted to near zero by controlling the TiO2 content and sintering temperature. The appearance of Al2TiO5 phase, resulted from the consumption of TiO2, exhibits intense effect on the microwave dielectric properties of (1-x)Al2O3 -xTiO2 ceramics. The major contributions in this research would be the lower sintering temperatures and the near 0 ppm/¢J of £nf value. The 2wt%- MCAS-added (1-x)Al2O3-xTiO2 ceramics sintered at 1300¢J and x = 0.12 has a minimum £nf value of ¡V0.6 ppm/¢J. In the second part of the dissertation, the microstrip antennas with high permittivity BiNbO4 ceramics (£`r = 43) substrate are fabricated. The bandwidths obtained are narrow and insufficient for the WLAN application. The techniques of U-slots patch and stacked structure are used to enhance the bandwidth of the microstrip ceramic antennas by combining the two adjacent resonant modes. The results indicate that the impedance bandwidth can be enhanced from 2.3% to 5.3% by embedding double U-shaped slots in the rectangular patch, or to 4.5% by using stacked patches.

For the application of 4G wireless communication system, this thesis aims to develop a high-quality-factor and low-power-dissipation suspending micro-inductor using electrochemical deposition and surface micromachining technologies. This research presents three technical points to improve the quality factor and reduce the power dissipation of micro inductor, including (i) to adopt a low resistivity material (copper) as the conducting layer to decrease the Eddy current due to the skin effect and reduce the total series resistance and energy loss, (ii) to utilize a suspending structure to diminish the power loss through the substrate and (iii) to replace the silicon wafer with a high resistance substrate (Corning 7740) to compress effectively the power dissipation in high frequency operation. The implemented suspending micro-inductors were characterized by a commercial network analyzer (Agilent E5071C) under 0.5~20 GHz testing frequency range. All the inductances and quality factors of the micro-inductors proposed in this thesis are extracted by the Agilent ADS software. The optimized value of the quality factor is around to 24.9 and the corresponding inductance is equal to 5.43 nH .

Title from PDF of title page. / Document formatted into pages; contains 88 pages. / Thesis (M.S.E.E.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: In this work, a multi dimensional RF MEMS variable capacitor that utilizes electrostatic actuation is designed and fabricated on a 425um thick silicon substrate. Electrostatic actuation is preferred over other actuation mechanisms due to low power consumption. The RF MEMS variable capacitor is designed in a CPW topology, with multiple beams supported (1 - 7 beams) on a single pedestal. The varactors are fabricated using surface micromachining techniques. A 1um thick silicon monoxide (Er - 6) is used as a dielectric layer for the varactor. The movable membrane is suspended on a 2.5um thick electroplated gold pedestal. The capacitance between the membrane and the bottom electrode increases as the bias voltage between the membrane and the bottom electrode is increased, eventually causing the membrane to snap down at the actuation voltage. For the varactors designed herein, the actuation voltage is approximately 30 - 90V. / ABSTRACT: Full-wave electromagnetic simulations are performed from 1 - 25GHz to accurately predict the frequency response of the varactors. The EM simulations and the measurement results compare favorably. A series RLC equivalent circuit is used to model the varactor and used to extract the parasitics associated with the capacitor by optimizing the model with the measurement results. The measured capacitance ratio is approximately 12:1 with a tuning range from 0.5 - 6pF. Furthermore, the measured S-parameter data is used to extract the unloaded Q of the varactor (at 1GHz) and is found to be 234 in the up state and 27 in the down state. An improved anodic bonding technique to bond high resistivity Si substrate and low alkali borax glass substrate that finds potential application towards packaging of MEMS varactors is investigated. To facilitate the packaging of the varactors the temperature is maintained at 400°C. The bonding time is approximately 7min at an applied voltage of 1KV. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

As seismic waves travel through the earth, the visco-elasticity of the earth's medium will cause energy dissipation and waveform distortion. This phenomenon is referred to as seismic absorption or attenuation. The absorptive property of a medium can be described by a quality factor Q, which determines the energy decay and a velocity dispersion relationship. Four new ideas have been developed in this thesis to deal with the estimation and application of seismic absorption. By assuming that the amplitude spectrum of a seismic wavelet may be modeled by that of a Ricker wavelet, an analytical relation has been derived to estimate a quality factor from the seismic data peak frequency variation with time. This relation plays a central role in quality factor estimation problems. To estimate interval Q for reservoir description, a method called reflectivity guided seismic attenuation analysis is proposed. This method first estimates peak frequencies at a common midpoint location, then correlates the peak frequency with sparsely-distributed reflectivities, and finally calculates Q values from the peak frequencies at the reflectivity locations. The peak frequency is estimated from the prestack CMP gather using peak frequency variation with offset analysis which is similar to amplitude variation with offset analysis in implementation. The estimated Q section has the same layer boundaries of the acoustic impedance or other layer properties. Therefore, the seismic attenuation property obtained with the guide of reflectivity is easy to interpret for the purpose of reservoir description. To overcome the instability problem of conventional inverse Q filtering, Q compensation is formulated as a least-squares (LS) inverse problem based on statistical theory. The matrix of forward modeling is composed of time-variant wavelets. The LS de-absorption is solved by an iterative non-parametric approach. To compensate for absorption in migrated seismic sections, a refocusing technique is developed using non-stationary multi-dimensional deconvolution. A numerical method is introduced to calculate the blurring function in layered media, and a least squares inverse scheme is used to remove the blurring effect in order to refocus the migrated image. This refocusing process can be used as an alternative to regular migration with absorption compensation.

For the past decade, a great deal of research has been focused towards developing a viable on-chip solution to replace the current state-of-the-art VHF and UHF filters based on SAW and FBAR technologies. Although filters based on SAW and FBAR devices are capable of fulfilling the basic requirements needed for IF and RF bandpass filtering and reference signal generation, an alternative solution that can enable the next generation of multi-frequency and multi-mode transceivers while enabling size and price reduction by allowing the manufacturing of single-chip monolithic RF transceivers is highly desired. In response to these new needs, piezoelectrically-transduced micromechanical filters have emerged as a plausible alternative to outperform current dominant technologies in size, cost, and IC manufacturing compatibility without compromising device performance in terms of insertion loss, rejection, power handling and linearity. This dissertation presents the design, fabrication, characterization and experimental analysis of low-loss VHF and UHF filters for wireless communication applications, based on piezoelectrically-transduced micromechanical resonators. The resonators employed in this work for the implementation of microwave filters, resonate in contour-mode shapes, which differ from commercially available thickness-mode FBAR resonators, for which the thickness sets the resonance frequency. The employment of contour-mode designs facilitate simultaneous synthesis of multiple frequencies on the same substrate through CAD layout-defined lateral dimensions, thus avoiding the complexity demanded by FBAR devices for the precise control of the piezoelectric layer thickness. Moreover, filters composed of acoustically-coupled piezoelectrically-transduced resonators operating at higher order modes with sizes up to 10 times smaller than their SAW counterparts operating at the same UHF range have been successfully implemented, without jeopardizing the key filter specifications. Throughout this dissertation, piezoelectrically-transduced MEMS filters based on mechanically, electrically and acoustically coupled contour-mode resonator(s) or resonator arrays were designed and fabricated. Filters with insertion loss as low as 2.6 dB at IF frequencies and 4.0 dB at RF frequencies have been demonstrated. Moreover, synthesized filters with extremely narrow bandwidth of 0.1 % and 0.2 % at frequencies between 160 MHz and 215 MHz have been developed, which comply the specifications for IF filters for GSM handsets. This particular type of filters each consist of just one single high-Q resonator, which leverages single crystalline silicon as the major part of their structure to obtain the sufficient quality factor required for the implementation of such small bandwidth. Among the most significant results, this dissertation presents two thin film piezoelectrically-transduced monolithic filters operating at 482 MHz and 536 MHz, which can be interfaced directly to a 377  antenna without the need of external matching components. This dissertation also has conducted a systematic comparison between commercial available SAW filters and the MEMS filters synthesized using piezoelectrically-transduced resonators. Parameters such as group delay and third intermodulation (IP3) have been measured and carefully compared. Evidentially, most of the fabricated piezoelectrically-transduced filters developed by this work have exhibited a similar or superior performance as compared to their commercial SAW counterparts

One of the chief components in a RF/microwave circuit is the inductor. The performance of the inductor affects the performance of widely used circuits such as the voltage controlled oscillator (VCO), low noise amplifier, and filter in the RF front end. It is very important to design inductors for accurate values of inductances and sufficiently high quality factors for these microwave applications. A key challenge in achieving high unloaded Q for an inductor in a thin substrate is the ground separation. This thesis aims at addressing this issue and achieving high unloaded Q's in the range 150 - 200 for a ground separation of about 100 - 140 microns in the frequency range of 1 - 15 GHz. One port and inductors will be designed using Electromagnetic field solvers. Various topologies will be explored for 2D and 3D inductors with the aim of achieving the desired inductance density and Q parameters in a minimum area possible. In order to address the issue of ground separation, design modifications will include the use of patterned grounds to take advantage of the reduced parasitic capacitive coupling which enables a high Q factor. The objective of the thesis also includes demonstration of the usefulness of these high quality inductors in RF front ends. To this effect, proof of concept designs of LC band pass filters will be presented. To enable this design, capacitors will also be designed. An extensive library of the designed inductors will be presented as a part of the thesis. The designed components will be fabricated at the Packaging Research Center (PRC), Georgia Tech using organic substrate compatible processes. High frequency measurements will be made with the Vector Network Analyzer (VNA) along with suitable de - embedding to demonstrate the correlation between designed and fabricated results. Following this, circuit models will be built for the characterized inductors.

The energy deposition characteristics of heavy ions vary substantially compared to those of photons. Many radiation biology studies have compared the damaging effects of different types of radiation to establish relative biological effectiveness among them. These studies are dependent on cell type, biological endpoint, radiation type, dose, and dose rate. The radiation field found in space is much more complicated than that simulated in most experiments, both from a point of dose-rate as well as the highly mixed field of radiative particles encompassing a broad spectrum of energies. To establish better estimates for radiation risks on long-term, deep space missions, the damaging ability of heavy ions requires further understanding. Track structure studies provide significant details about the spatial distribution of energy deposition events in and around the sensitive targets of a mammalian cell. The damage imparted by one heavy ion relative to another can be established by modeling the track structures of ions that make up the galactic cosmic ray (GCR) spectrum and emphasizing biologically relevant target geometries. This research was undertaken to provide a better understanding of the damaging ability of GCR at the cellular level. By comparing ions with equal stopping power values, the differences in track structure will illuminate variations in cell particle traversals and ionization density within cell nuclei. For a cellular target, increased particle traversals, along with increased ionization density, are key identifiers for increased damaging ability. Performing Monte Carlo simulations with the computer code, FLUKA, this research will provide cellular dosimetry data and detail the track structure of the ions. As shown in radiobiology studies, increased ionizations within a cell nucleus generally lead to increased DNA breaks and increased free radical production, resulting in increased carcinogenesis and cell death. The spatial distribution of dose surrounding ions tracks are compared for inter- and intracellular regions. A comparison can be made for many different ions based upon dose and particle fluence across those different regions to predict relative damaging ability. This information can be used to improve estimates for radiation quality and dose equivalent from the space radiation environment.

[Truncated abstract] The research described in this thesis investigated optical spring interactions and instabilities in a macroscopic opto-mechanical resonator. The thesis describes an experiment designed to model an optical spring `tranquiliser’ cavity which has been proposed to suppress the predicted parametric instabilities in the next generation of interferometric gravitational wave detectors. In a series of experiments, the optical spring effect was observed in macroscopic optical cavities through measured changes in mechanical stiffness, and measured changes in mechanical loss. The optical spring effect was further characterised through investigation of its dependent parameters. Two pairs of identical, low optical loss mirrors were bonded to a mechanical structure using a novel low mechanical loss technique, forming an opto-mechanical composite resonator. The technique uses the naturally occurring resin Yacca gum as a bonding agent. This resulted in the formation of two optical cavities with a length of l = 0.100±0.001m, only one of which was used in experiments. Using finite element modelling, the resonator?s two lowest modes, with frequencies of fm1 = 722.8Hz and fm2 = 747.9Hz, and an effective mass 0.0323±0.0001kg, were found to be subject to the optical spring effect. ... The instabilities are expected to have a parametric gain factor of up to 100 in the frequency range of 15-120kHz. Therefore, if optical spring damping can be made large enough to reduce the Q-factor of the Advanced LIGO test-masses by a factor of 100, all parametric instabilities should be eliminated. For a simple servo loop and an optical cavity with the practically achievable finesse of F = 30,000, a tranquiliser cavity length of 1.3cm was found to produce optimum enhanced damping. This configuration only requires 1.47W of input power, resulting in an intra-cavity power of 5.72kW. The cavity mirrors were assumed to have optical coatings with a damage threshold of 1MW/cm2, which limited the spot size to a minimum area of 0.572mm2, or a radial beam waist of w = 0.427mm. This nearly flat-flat cavity has a stability g-factor of 0.9997. Even given these technical challenges, suppression of the parametric instabilities predicted to occur in the next generation of interferometric detectors is possible to achieve practically using enhanced optical spring damping. A possible design for such a tranquiliser cavity is also suggested.