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Title: ANALOG TEMPERATURE CONTROL CIRCUIT FOR A THIN-FILM PIEZOELECTRIC-ON-SUBSTRATE MICROELECTROMECHANICAL SYSTEMS OSCILLATOR.
Creator: Hofstee, Heather, Abdolvand, Reza, University of Central Florida
Abstract / Description: The objective and motivation for this project is to design a low-power, low-noise oven-control circuit to optimize the stability of a MEMS oscillator. MEMS oscillators can be fabricated using conventional semiconductor manufacturing methods and can often be assembled in packages smaller than those of traditional crystal oscillators. However, one of their largest disadvantages currently is their high temperature coefficient of frequency (TCF), causing MEMS oscillators to be especially...
Show moreThe objective and motivation for this project is to design a low-power, low-noise oven-control circuit to optimize the stability of a MEMS oscillator. MEMS oscillators can be fabricated using conventional semiconductor manufacturing methods and can often be assembled in packages smaller than those of traditional crystal oscillators. However, one of their largest disadvantages currently is their high temperature coefficient of frequency (TCF), causing MEMS oscillators to be especially sensitive to temperature changes. Hence, this project focuses on designing a printed circuit board that will allow the user to manually tune a current passing through a resonator wire-bonded to the board to elevate the resonator temperature. This will ensure that the device's resonance frequency stays largely constant and that the oscillator provides a very stable signal.
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Date Issued: 2018
Identifier: CFH2000419, ucf:45748
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH2000419

Title: Controlled Bubble Dynamics Inside Micropillar Arrays.
Creator: Khalil Arya, Faraz, Peles, Yoav, Gou, Jihua, Kassab, Alain, Abdolvand, Reza, University of Central Florida
Abstract / Description: Bubble dynamics inside micro domains was manipulated and used to pump liquid. Micropillars were formed inside two 1.5 mm wide and 220 (&)#181;m high microchannels with a length of 23 mm. One microchannel had three arrays of micropillars with diameters of 40 (&)#181;m and the other had a single array of micropillars with diameters of 30 (&)#181;m. An array of five 200 (&)#181;m by 200 (&)#181;m heaters was deposited inside these micropillar arrays and was used to control bubble size and...
Show moreBubble dynamics inside micro domains was manipulated and used to pump liquid. Micropillars were formed inside two 1.5 mm wide and 220 (&)#181;m high microchannels with a length of 23 mm. One microchannel had three arrays of micropillars with diameters of 40 (&)#181;m and the other had a single array of micropillars with diameters of 30 (&)#181;m. An array of five 200 (&)#181;m by 200 (&)#181;m heaters was deposited inside these micropillar arrays and was used to control bubble size and trajectory. A sequential power switching of the heaters was used to pump liquid in a desired direction with a flow rate of up to 133 (&)#181;l/min for the three arrays micropillars microchannel and up to 44.4 (&)#181;l/min for the single array micropillars device.
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Date Issued: 2018
Identifier: CFE0007757, ucf:52381
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007757

Title: Excellent Surface Passivation for High Efficiency C_Si Solar Cells.
Creator: Bakhshi, Sara, Schoenfeld, Winston, Abdolvand, Reza, Sundaram, Kalpathy, Davis, Kristopher, University of Central Florida
Abstract / Description: Semiconductor surface clean is sometimes perceived as costly but long recognized as pivotal in determining the final semiconductor device performance and yield. In this contribution, we investigated the effectiveness of crystalline silicon surface cleaning by a simple UV-ozone process in comparison to the industry standard RCA clean for silicon photovoltaic applications. We present a unique method of processing the silicon surface effectively by UV-ozone cleaning. Despite being simple, UV...
Show moreSemiconductor surface clean is sometimes perceived as costly but long recognized as pivotal in determining the final semiconductor device performance and yield. In this contribution, we investigated the effectiveness of crystalline silicon surface cleaning by a simple UV-ozone process in comparison to the industry standard RCA clean for silicon photovoltaic applications. We present a unique method of processing the silicon surface effectively by UV-ozone cleaning. Despite being simple, UV-ozone cleaning results in a superior surface passivation quality that is comparable to high-quality RCA clean. When used as a stack dielectric(-)UV-ozone oxide overlaid by aluminum oxide(-)the thickness of UV-ozone oxide plays an important role in determining the passivation quality. Of all treatment times, 15 min of UV-ozone treatment results in an outstanding passivation quality, achieving the effective carrier lifetime of 3 ms and saturation current density of 5 fA/cm2. In addition, we present a simple and effective technique to extract values of electron/hole capture cross-section for the purpose of analyzing the interface passivation quality from already measured surface recombination parameters of saturation current density, interfacial trap density and total fixed charge, instead of measuring on the separately prepared metal-insulated-semiconductor (MIS) samples by the techniques: frequency-dependent parallel conductance or deep-level transient spectroscopy.
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Date Issued: 2018
Identifier: CFE0007154, ucf:52313
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007154

Title: Wearable Passive Wireless MEMS Respiration Sensor.
Creator: Moradian, Sina, Abdolvand, Reza, Sundaram, Kalpathy, Kapoor, Vikram, University of Central Florida
Abstract / Description: In this study a passive sensor that wirelessly monitors the profile of the human respiratory system is presented. The sensor was designed to be wearable, weighs less than 10 grams and is durable. The sensor is made of a RF piezoelectric MEMS resonator and an ultra-high frequency antenna made of a thin metal film formed on a flexible substrate . The resonance frequency of the TPoS resonator shifts as a function of condensation and evaporation of water vapor on the surface of the resonator and...
Show moreIn this study a passive sensor that wirelessly monitors the profile of the human respiratory system is presented. The sensor was designed to be wearable, weighs less than 10 grams and is durable. The sensor is made of a RF piezoelectric MEMS resonator and an ultra-high frequency antenna made of a thin metal film formed on a flexible substrate . The resonance frequency of the TPoS resonator shifts as a function of condensation and evaporation of water vapor on the surface of the resonator and changes in resonator's temperature. These parameters change in each in response to inspiration and expiration and a wireless measurement system detects the frequency shift of the sensor and converts it into the respiration profile. The respiration profile of a healthy human subject is measured and presented for a transmitter to sensor to receiver distance of ~25cm.
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Date Issued: 2017
Identifier: CFE0006628, ucf:51279
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006628

Title: Local transient characterization of thermofluid heat transfer coefficient at solid-liquid nano-interfaces.
Creator: Mehrvand, Mehrdad, Putnam, Shawn, Peles, Yoav, Orlovskaya, Nina, Abdolvand, Reza, University of Central Florida
Abstract / Description: The demands for increasingly smaller, more capable, and higher power density technologies in microelectronics, energy, or aerospace systems have heightened the need for new methods to manage and characterize extreme heat fluxes (EHF). Microscale liquid cooling techniques are viewed as a promising solution for removing heat from high heat flux (HHF) systems. However, there have been challenges in physical understanding and predicting local thermal transport at the interface of micro and...
Show moreThe demands for increasingly smaller, more capable, and higher power density technologies in microelectronics, energy, or aerospace systems have heightened the need for new methods to manage and characterize extreme heat fluxes (EHF). Microscale liquid cooling techniques are viewed as a promising solution for removing heat from high heat flux (HHF) systems. However, there have been challenges in physical understanding and predicting local thermal transport at the interface of micro and nanoscale structures/devices due to ballistic effects and complex coupling of mass, momentum, and energy transport at the solid-liquid-vapor interfaces over multiple time and length scales. Moreover, it's challenging to experimentally validate new HHF models due to lack of high resolution techniques and measurements.This dissertation presents the use of a high spatiotemporal and temperature resolution measurement technique, called Time-domain Thermoreflectance (TDTR). TDTR is used to characterize the local heat transfer coefficient (HTC) of a water-cooled rectangular microchannel in a combined hot-spot heating and sub-cooled channel-flow configuration. Studies focused on room temperature, syringe-pumped single-and two-phase water flow in a ?480 ?m hydraulic diameter microchannel, where the TDTR pump heating laser induces local heat fluxes of ?0.5-2.5 KW/cm2 in the center of the microchannel on the surface of a 60-80 nm metal or alloy thin film transducer with hot-spot diameters of ?7-10 ?m. In the single-phase part, a differential measurement approach is developed by applying anisotropic version of the TDTR to predict local HTC using the measured voltage ratio parameter, and then fitting data to a thermal model for layered materials and interfaces. It's shown that thermal effusivity distribution of the water coolant over the hot-spot is correlated to the local HTC, where both the stagnant fluid (i.e., conduction and natural convection) and flowing fluid (i.e., forced convection) contributions are decoupled from each other. Measurements of the local enhancement in the HTC over the hot-spot are in good agreement with established Nusselt number correlations. For example, flow cooling results using a Ti metal wall support a maximum HTC enhancement via forced convection of ?1060(&)#177;190 kW/m2?K, where the well-established Nusselt number correlations predict ?900(&)#177;150 kW/m2?K.In the two-phase part, pump-probe beams are first used to construct the local pool and flow boiling curves at different heat fluxes and hot spot temperatures as a function of HTC enhancement. At a same heat flux level, it's observed that fluid flow enhances HTC by shifting heat transfer mechanism (or flow regime) from film boiling to nucleate boiling. Based on observations, it's hypothesized that beyond an EHF flow may reduce the bubble size and increase evaporation at the liquid-vapor interface on three-phase contact line, but it's unable to rewet and cool down the dry spot at the center due to the EHF. In the last part of two-phase experiments, transient measurements are performed at a specific heat flux to obtain thermal temporal fluctuations and HTC of a single bubble boiling and nucleation during its ebullition cycle. The total laser power is chosen to be between the minimum required to start subcooled nucleation and CHF of the pool boiling. This range is critical since within 10% change in heating flux, flow can have dramatic effect on HTC. Whenever the flow gets closer to the dry spot and passes through it (receding or advancing) HTC increases suddenly. This means that for very hot surfaces (or regions of wall dry-out), continuous and small bubbles on the order of thermal diffusion time and dry spot length scales respectively could be a reliable high heat flux cooling solution. This could be achieved by controlling the bubble size and frequency through geometry, surface structure and properties, and fluid's thermos-fluid properties.
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Date Issued: 2017
Identifier: CFE0006765, ucf:51832
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006765

Title: Spray_Deposited Titanium-Oxide Films For Infrared Optics, Photonics, And Solar Cell Applications.
Creator: Alhasan, Sarmad, Peale, Robert, Sundaram, Kalpathy, Mikhael, Wasfy, Abdolvand, Reza, Kar, Aravinda, University of Central Florida
Abstract / Description: Self-assembled TiO2 foam-like films, were grown by the water based Streaming Process for ElectrodelessElectrochemical Deposition (SPEED). The morphology of the 1 m thick films consistsof a tangled ropy structure with individual strands of 200 nm diameter and open pores of 0.1to 3 micron dimensions. Such films are advantageous for proposed perovskite solar cell comprisingCH3NH3PbI3 absorber with additional inorganic films as contact and conduction layers,all deposited by SPEED. Lateral film...
Show moreSelf-assembled TiO2 foam-like films, were grown by the water based Streaming Process for ElectrodelessElectrochemical Deposition (SPEED). The morphology of the 1 m thick films consistsof a tangled ropy structure with individual strands of 200 nm diameter and open pores of 0.1to 3 micron dimensions. Such films are advantageous for proposed perovskite solar cell comprisingCH3NH3PbI3 absorber with additional inorganic films as contact and conduction layers,all deposited by SPEED. Lateral film resistivity is in the range 20 - 200 k-cm, increasing withgrowth temperature, while sheet resistance is in the range 2 ?? 20 108 /Sq. Xray diffractionconfirms presence of TiO2 crystals of orthorhombic class (Brookite). UV-vis spectroscopy showshigh transmission below the expected 3.2 eV TiO2 bandgap. Transmittance increases with growthtemperature. This is a Ropy TiO2 thin film.We also prepared a Smooth TiO2 thin film. Self-assembled TiO2 film deposited by aqueous-spraydeposition was investigated to evaluate morphology, crystalline phase, and infrared optical constants.The Anatase nano-crystalline film had 10 nm characteristic surface roughness sparselypunctuated by defects of not more than 200 nm amplitude. The film is highly transparent throughoutthe visible to wavelengths of 12 m. The indirect band gap was determined to be 3.2 eV. Importantfor long-wave infrared applications is that dispersion in this region is weak compared with themore commonly used dielectic SiO2 for planar structures. The low-cost, large-area, atmosphericpressure,chemical spray deposition method allows conformal fabrication on flexible substrates forlong-wave infrared photonics.For comparison TiO2 films deposited by electron-beam evaporation were evaluated to determinemorphology, crystalline phase, and optical transparency.The evaporated TiO2 film was amorphous but crystallized into Anatase phase after annealing.Such film is attractive as electron conductor of unprecedented thinness and flexibility for proposedperovskite solar cell comprising CH3NH3PbI3 absorber with additional inorganic films as contactand conduction layers. The spray deposition method would allow conformal solar cell fabricationon flexible substrates for wearable power generation. Band gap of Evaporated TiO2 film is 4.0 eV.We prepared BaTiO3 thin film to know infrared pyroelectric response.Self-assembled nano-crystalline BaTiO3 films on stainless steel foil substrates, were grown by thewater based Streaming Process for Electrodeless Electrochemical Deposition (SPEED). SPEED isan aqueous process that deposits self-assembled nano-crystalline inorganic thin films over largeareas, without a vacuum, providing a scalable and manufacturing friendly process to fabricatedurable films. The morphology of the 1m thick films comprises single crystals of micron dimensionsimbedded in a matrix of nanocrystals. XRD confirms presence of BaTiO3 crystals ofhexagonal phase for samples annealed at 500C. Subsequent annealing at 600C transforms thefilm to the cubic phase. Potential applications include dielectric layers, capacitors, waveguides,ferroelectric RAM, pyroelectric infrared detectors, and phosphors. Characterization of infraredpyroelectric response at 10m wavelength shows an initially good sensitivity that reversibly decaysover a period of days due to water vapor absorption. A short-lived photo-response due topoling of the hydrated sample is also observed. We studied BaTiO3 to know hysteresis loop.Pyroelectric photoresponse of aqueous spray deposited thin films containing BaTiO3 nano-crystalsis reported. X-ray diffraction data indicate the presence of hexagonal BaTiO3 nano-crystals with20 nm crystalline domains in a matrix of some as yet unidentified nano-crystalline material.When the film is annealed at 600C, the X-ray pattern changes significantly and indicates a conversionto one of the non-hexagonal phases of BaTiO3 as well as a complete change in the matrix.With suitable amplifier, the measured photoresponse was 40V/W.Ferroelectric hysteresis on a film with significant presence of hexagonal BaTiO3 shows saturatedpolarization which is about 5-times smaller than for the bulk tetragonal phase.
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Date Issued: 2017
Identifier: CFE0006710, ucf:51899
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006710

Title: Customizable Antenna Array Using Reconfigurable Antenna Elements.
Creator: Shirazi, Mahmoud, Gong, Xun, Wahid, Parveen, Jones, W Linwood, Abdolvand, Reza, Kuebler, Stephen, University of Central Florida
Abstract / Description: A shared-aperture reconfigurable slot-ring antenna array switching between different frequency bands and polarizations is presented for phased array applications. PIN diode switches are incorporated into the slots of the antenna to change the state of the reconfigurable slot-ring antenna array. Each frequency band has its own feeding lines which allows for the use of high-performance narrow-band transmit/receive (T/R) modules instead of ultra wideband (UWB) T/R modules. Furthermore, the...
Show moreA shared-aperture reconfigurable slot-ring antenna array switching between different frequency bands and polarizations is presented for phased array applications. PIN diode switches are incorporated into the slots of the antenna to change the state of the reconfigurable slot-ring antenna array. Each frequency band has its own feeding lines which allows for the use of high-performance narrow-band transmit/receive (T/R) modules instead of ultra wideband (UWB) T/R modules. Furthermore, the spacing between the elements in each frequency band is less than half free-space wavelength (?0) over the frequency band of operation which enables grating-lobe-free beam scanning. This is the first shared-aperture reconfigurable dual-polarized antenna with separate feeding for each band which is scalable to a larger array with element spacing of less than 0.5?0 in all frequency bands of operation.First, a switchable-band reconfigurable antenna array switching between L and C bands is presented. This antenna operates at 1.76/5.71 GHz with a fractional bandwidth (FBW) of 8.6%/11.5%, realized gain of 0.1/4.2 dBi and radiation efficiency of 66.6%/80.7% in the L-/C- band operating states, respectively. Second, a wideband version of the reconfigurable antenna element using fractal geometries is presented. This dual-polarized antenna element is switching between S and C bands with wide bandwidth in each operating state. In the S-/C-band operating state, this antenna shows 69.1%/58.3% FBW with a maximum realized gain of 2.4/3.1 dBi. Third, the wideband antenna element is extended to an antenna array. The reconfigurable dual-polarized antenna array with vertical coaxial feeding switches between S- and C-band states with full-band coverage. A 2(&)#215;2 S-band antenna array can be reconfigured to a 4(&)#215;4 C-band antenna array by activating/deactivating PIN diode switches. This antenna array shows 64.3%/66.7% FBW with 8.4/14.3 dBi maximum realized gain in the S-/C-band operating states, respectively. Finally, a reconfigurable antenna element covering three adjacent frequency bands is presented. The FBW of this tri-band antenna element is 75%/63%/26% in the S/C/X band state.
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Date Issued: 2018
Identifier: CFE0007373, ucf:52092
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007373

Title: Semiconductor Design and Manufacturing Interplay to Achieve Higher Yields at Reduced Costs using SMART Techniques.
Creator: Oberai, Ankush Bharati, Yuan, Jiann-Shiun, Abdolvand, Reza, Georgiopoulos, Michael, Sundaram, Kalpathy, Reilly, Charles, University of Central Florida
Abstract / Description: Since the outset of IC Semiconductor market there has been a gap between its design and manufacturing communities. This gap continued to grow as the device geometries started to shrink and the manufacturing processes and tools got more complex. This gap lowered the manufacturing yield, leading to higher cost of ICs and delay in their time to market. It also impacted performance of the ICs, impacting the overall functionality of the systems they were integrated in. However, in the recent years...
Show moreSince the outset of IC Semiconductor market there has been a gap between its design and manufacturing communities. This gap continued to grow as the device geometries started to shrink and the manufacturing processes and tools got more complex. This gap lowered the manufacturing yield, leading to higher cost of ICs and delay in their time to market. It also impacted performance of the ICs, impacting the overall functionality of the systems they were integrated in. However, in the recent years there have been major efforts to bridge the gap between design and manufacturing using software solutions by providing closer collaborations techniques between design and manufacturing communities. The root cause of this gap is inherited by the difference in the knowledge and skills required by the two communities. The IC design community is more microelectronics, electrical engineering and software driven whereas the IC manufacturing community is more driven by material science, mechanical engineering, physics and robotics. The cross training between the two is almost nonexistence and not even mandated. This gap is deemed to widen, with demand for more complex designs and miniaturization of electronic appliance-products. Growing need for MEMS, 3-D NANDS and IOTs are other drivers that could widen the gap between design and manufacturing. To bridge this gap, it is critical to have close loop solutions between design and manufacturing This could be achieved by SMART automation on both sides by using Artificial Intelligence, Machine Learning and Big Data algorithms. Lack of automation and predictive capabilities have even made the situation worse on the yield and total turnaround times. With the growing fabless and foundry business model, bridging the gap has become even more critical. Smart Manufacturing philosophy must be adapted to make this bridge possible. We need to understand the Fab-fabless collaboration requirements and the mechanism to bring design to the manufacturing floor for yield improvement. Additionally, design community must be educated with manufacturing process and tool knowledge, so they can design for improved manufacturability. This study will require understanding of elements impacting manufacturing on both ends of the design and manufacturing process. Additionally, we need to understand the process rules that need to be followed closely in the design phase. Best suited SMART automation techniques to bridge the gap need to be studied and analyzed for their effectiveness.
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Date Issued: 2018
Identifier: CFE0007351, ucf:52096
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007351

Title: HIGH QUALITY GATE DIELECTRIC/MoS2 INTERFACES PROBED BY THE CONDUCTANCE METHOD.
Creator: Krishnaprasad Sharada, Adithi Pandrahal, Roy, Tania, Abdolvand, Reza, Yuan, Jiann-Shiun, University of Central Florida
Abstract / Description: Two-dimensional materials provide a versatile platform for various electronic and optoelectronic devices, due to their uniform thickness and pristine surfaces. We probe the superior quality of 2D/2D and 2D/3D interfaces by fabricating molybdenum disulfide (MoS2)-based field effect transistors having hexagonal boron nitride (h-BN) and Al2O3 as the top gate dielectrics. An extremely low trap density of ~7x10^10 states/cm2-eV is extracted at the 2D/2D interfaces with h-BN as the top gate...
Show moreTwo-dimensional materials provide a versatile platform for various electronic and optoelectronic devices, due to their uniform thickness and pristine surfaces. We probe the superior quality of 2D/2D and 2D/3D interfaces by fabricating molybdenum disulfide (MoS2)-based field effect transistors having hexagonal boron nitride (h-BN) and Al2O3 as the top gate dielectrics. An extremely low trap density of ~7x10^10 states/cm2-eV is extracted at the 2D/2D interfaces with h-BN as the top gate dielectric on the MoS2 channel. 2D/3D interfaces with Al2O3 as the top gate dielectric and SiOx as the nucleation layer exhibit trap densities between 7x10^10 and 10^11 states/cm2-eV, which is lower than previously reported 2D-channel/high-k-dielectric interface trap densities. The comparable values of trap time constants for both interfaces imply that similar types of defects contribute to the interface traps. This work establishes the case for van der Waals systems where the superior quality of 2D/2D and 2D/high-k dielectric interfaces can produce high performance electronic and optoelectronic devices.
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Date Issued: 2018
Identifier: CFE0007214, ucf:52209
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007214

Title: Fundamental Properties of Metallic Nanolasers.
Creator: Hayenga, William, Khajavikhan, Mercedeh, Christodoulides, Demetrios, Likamwa, Patrick, Abdolvand, Reza, University of Central Florida
Abstract / Description: The last two decades have witnessed tremendous advancements in the area of nanophotonics and plasmonics, which has helped propel the development of integrated photonic sources. Of central importance to such circuits is compact, scalable, low threshold, and efficient coherent sources that can be driven at high modulation frequencies. In this regard, metallic nanolasers offer a unique platform. Their introduction has enabled confinement of light at a subwavelength scale and the ultra-small size...
Show moreThe last two decades have witnessed tremendous advancements in the area of nanophotonics and plasmonics, which has helped propel the development of integrated photonic sources. Of central importance to such circuits is compact, scalable, low threshold, and efficient coherent sources that can be driven at high modulation frequencies. In this regard, metallic nanolasers offer a unique platform. Their introduction has enabled confinement of light at a subwavelength scale and the ultra-small size of the modes afforded by these structures allows for cavity enhancing effects that can help facilitate thresholdless lasing and large direct modulation bandwidths. In this report, I present my work on the study of the fundamental properties of metallic nanolasers. I start with a rate equation model to predict threshold behavior and the modulation response of metallic nanolasers. Next, I explain the second-order coherence measurement setup that was built, based on a modified Hanbury-Brown and Twiss experiment, to assess the intensity autocorrelation of various optically pumped metallic nanolasers. These studies concluded that metallic coaxial and disk-shaped nanolasers are capable of generating truly coherent radiation. Subsequently, design considerations are taken into account for electrically pumped coaxial nanolasers. This has led to the demonstration of electrically injected coaxial and disk-shaped nanolasers at cryogenic temperatures. Lastly, the appearance of collective behaviors in metallic nanolasers lattices is explored. Individually supporting modes that are highly vectorial by nature, when such cavities are fabricated in close proximity to one another, coupling through their overlapping fields results in the formation of a set of supermodes. The tendency of the system to minimize the overall loss leads to each element of the lattice having a geometric dependent field distribution and helps promotes single-mode lasing. We show both through simulations and experimentally that this effect can lead to the direct generation of vector vortices.
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Date Issued: 2018
Identifier: CFE0007752, ucf:52391
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007752

Title: Frequency-Reconfigurable Microstrip Patch and Cavity-Backed Slot ESPARs.
Creator: Ouyang, Wei, Gong, Xun, Vosoughi, Azadeh, Wahid, Parveen, Abdolvand, Reza, Kuebler, Stephen, University of Central Florida
Abstract / Description: Wireless communication systems have rapidly evolved over the past decade which has led to an explosion of mobile data traffic. Since more and more wireless devices and sensors are being connected, the transition from the current 4G/LTE mobile network to 5G is expected to happen within the next decade. In order to improve signal-to-noise ratio (SNR), system capacity, and link budget, beam steerable antenna arrays are desirable due to their advantage in spatial selectivity and high directivity....
Show moreWireless communication systems have rapidly evolved over the past decade which has led to an explosion of mobile data traffic. Since more and more wireless devices and sensors are being connected, the transition from the current 4G/LTE mobile network to 5G is expected to happen within the next decade. In order to improve signal-to-noise ratio (SNR), system capacity, and link budget, beam steerable antenna arrays are desirable due to their advantage in spatial selectivity and high directivity. Electronically steerable parasitic array radiator (ESPAR) that can achieve low-cost continuously beamsteering using varactor diodes have attracted a lot of attention. This dissertation explores bandwidth enhancement of the ESPAR using frequency-reconfigurable microstrip patch and cavity-backed slot (CBS) antennas. In chapter 2, an ESPAR of three closely-coupled rectangular patch elements that do not use phase shifters is presented; the beamsteering is realized by tunable reactive loads which are used to control the mutual coupling between the elements. Additional loading varactors are strategically placed on the radiating edge of all the antenna elements to achieve a 15% continuous frequency tuning range while simultaneously preserving the beamsteering capability at each operating frequency. Therefore, this frequency-reconfigurable ESPAR is able to provide spectrum diversity in addition to the spatial diversity inherent in a frequency-fixed ESPAR. A prototype of the patch ESPAR is fabricated and demonstrated to operate from 0.87 to 1.02 GHz with an instantaneous fractional bandwidth (FBW) of ~1%. At each operating frequency, this ESPAR is able to scan from -20 to +20 degrees in the H plane. However, the beamsteering of the patch ESPAR is limited in the H-plane and its instantaneous S11 fractional bandwidth (FBW) is very narrow. This dissertation also explores how to achieve 2-D beamsteering with enhanced FBW using CBS antennas. A 20-element cavity-backed slot antenna array is designed and fabricated based on a CBS ESPAR cross subarray in chapter 5. This ESPAR array is able to steer the main beam from +45 degrees to -45 degrees in the E plane and from +40 degrees to -40 degrees in the H plane, respectively, without grating lobes in either plane. The impedance matching is maintained below -10 dB from 6.0 to 6.4 GHz (6.4% fractional bandwidth) at all scan angles. In addition, the CBS ESPAR exhibits minimum beam squint at all scan angles within the impedance matching bandwidth. This array successfully demonstrates the cost savings and associated reduction in the required number of phase shifters in the RF front end by employing ESPAR technology.
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Date Issued: 2019
Identifier: CFE0007699, ucf:52426
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007699

Title: Design and Implementation of Silicon-Based MEMS Resonators for Application in Ultra Stable High Frequency Oscillators.
Creator: Shahraini, Sarah, Abdolvand, Reza, Gong, Xun, Sundaram, Kalpathy, Kapoor, Vikram, Rajaraman, Swaminathan, University of Central Florida
Abstract / Description: The focus of this work is to design and implement resonators for ultra-stable high-frequency ((>)100MHz) silicon-based MEMS oscillators. Specifically, two novel types of resonators are introduced that push the performance of silicon-based MEMS resonators to new limits. Thin film Piezoelectric-on-Silicon (TPoS) resonators have been shown to be suitable for oscillator applications due to their combined high quality factor, coupling efficiency, power handling and doping-dependent temperature...
Show moreThe focus of this work is to design and implement resonators for ultra-stable high-frequency ((>)100MHz) silicon-based MEMS oscillators. Specifically, two novel types of resonators are introduced that push the performance of silicon-based MEMS resonators to new limits. Thin film Piezoelectric-on-Silicon (TPoS) resonators have been shown to be suitable for oscillator applications due to their combined high quality factor, coupling efficiency, power handling and doping-dependent temperature-frequency behavior. This thesis is an attempt to utilize the TPoS platform and optimize it for extremely stable high-frequency oscillator applications.To achieve the said objective, two main research venues are explored. Firstly, quality factor is systematically studied and anisotropy of single crystalline silicon (SCS) is exploited to enable high-quality factor side-supported radial-mode (aka breathing mode) TPoS disc resonators through minimization of anchor-loss. It is then experimentally demonstrated that in TPoS disc resonators with tethers aligned to [100], unloaded quality factor improves from ~450 for the second harmonic mode at 43 MHz to ~11,500 for the eighth harmonic mode at 196 MHz. Secondly, thickness quasi-Lam(&)#233; modes are studied and demonstrated in TPoS resonators for the first time. It is shown that thickness quasi-Lam(&)#233; modes (TQLM) could be efficiently excited in silicon with very high quality factor (Q). A quality factor of 23.2 k is measured in vacuum at 185 MHz for a fundamental TQLM-TPoS resonators designed within a circular acoustic isolation frame. Quality factor of 12.6 k and 6 k are also measured for the second- and third- harmonic TQLM TPoS resonators at 366 MHz and 555 MHz respectively. Turn-over temperatures between 40 (&)deg;C to 125 (&)deg;C are also designed and measured for TQLM TPoS resonators fabricated on degenerately N-doped silicon substrates. The reported extremely high quality factor, very low motional resistance, and tunable turn-over temperatures (>)80 (&)#186;C make these resonators a great candidate for ultra-stable oven-controlled high-frequency MEMS oscillators.
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Date Issued: 2019
Identifier: CFE0007861, ucf:52775
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007861

Title: Normally-Off Computing Design Methodology Using Spintronics: from Devices to Architectures.
Creator: Roohi, Arman, DeMara, Ronald, Abdolvand, Reza, Wang, Jun, Fan, Deliang, Del Barco, Enrique, University of Central Florida
Abstract / Description: Energy-harvesting-powered computing offers intriguing and vast opportunities to dramatically transform the landscape of Internet of Things (IoT) devices and wireless sensor networks by utilizing ambient sources of light, thermal, kinetic, and electromagnetic energy to achieve battery-free computing. In order to operate within the restricted energy capacity and intermittency profile of battery-free operation, it is proposed to innovate Elastic Intermittent Computation (EIC) as a new duty-cycle...
Show moreEnergy-harvesting-powered computing offers intriguing and vast opportunities to dramatically transform the landscape of Internet of Things (IoT) devices and wireless sensor networks by utilizing ambient sources of light, thermal, kinetic, and electromagnetic energy to achieve battery-free computing. In order to operate within the restricted energy capacity and intermittency profile of battery-free operation, it is proposed to innovate Elastic Intermittent Computation (EIC) as a new duty-cycle-variable computing approach leveraging the non-volatility inherent in post-CMOS switching devices. The foundations of EIC will be advanced from the ground up by extending Spin Hall Effect Magnetic Tunnel Junction (SHE-MTJ) device models to realize SHE-MTJ-based Majority Gate (MG) and Polymorphic Gate (PG) logic approaches and libraries, that leverage intrinsic-non-volatility to realize middleware-coherent, intermittent computation without checkpointing, micro-tasking, or software bloat and energy overheads vital to IoT. Device-level EIC research concentrates on encapsulating SHE-MTJ behavior with a compact model to leverage the non-volatility of the device for intrinsic provision of intermittent computation and lifetime energy reduction. Based on this model, the circuit-level EIC contributions will entail the design, simulation, and analysis of PG-based spintronic logic which is adaptable at the gate-level to support variable duty cycle execution that is robust to brief and extended supply outages or unscheduled dropouts, and development of spin-based research synthesis and optimization routines compatible with existing commercial toolchains. These tools will be employed to design a hybrid post-CMOS processing unit utilizing pipelining and power-gating through state-holding properties within the datapath itself, thus eliminating checkpointing and data transfer operations.
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Date Issued: 2019
Identifier: CFE0007526, ucf:52619
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007526

Title: Predictive modeling for assessing the reliability of bypass diodes in Photovoltaic modules.
Creator: Shiradkar, Narendra, Sundaram, Kalpathy, Schoenfeld, Winston, Atia, George, Abdolvand, Reza, Xanthopoulos, Petros, University of Central Florida
Abstract / Description: Solar Photovoltaics (PV) is one of the most promising renewable energy technologies for mitigating the effect of climate change. Reliability of PV modules directly impacts the Levelized Cost of Energy (LCOE), which is a metric for cost competitiveness of any energy technology. Further reduction in LCOE of PV through assured long term reliability is necessary in order to facilitate widespread use of solar energy without the need for subsidies. This dissertation is focused on frameworks for...
Show moreSolar Photovoltaics (PV) is one of the most promising renewable energy technologies for mitigating the effect of climate change. Reliability of PV modules directly impacts the Levelized Cost of Energy (LCOE), which is a metric for cost competitiveness of any energy technology. Further reduction in LCOE of PV through assured long term reliability is necessary in order to facilitate widespread use of solar energy without the need for subsidies. This dissertation is focused on frameworks for assessing reliability of bypass diodes in PV modules. Bypass diodes are critical components in PV modules that provide protection against shading. Failure of bypass diode in short circuit results in reducing the PV module power by one third, while diode failure in open circuit leaves the module susceptible for extreme hotspot heating and potentially fire hazard. PV modules, along with the bypass diodes are expected to last at least 25 years in field. The various failure mechanisms in bypass diodes such as thermal runaway, high temperature forward bias operation and thermal cycling are discussed. Operation of bypass diode under shading is modeled and method for calculating the module I-V curve under any shading scenario is presented. Frameworks for estimating the diode temperature in field deployed modules based on Typical Meteorological Year (TMY) data are developed. Model for predicting the susceptibility of bypass diodes for thermal runaway is presented. Diode wear out due to High Temperature Forward Bias (HTFB) operation and Thermal Cycling (TC) is studied under custom designed accelerated tests. Overall, this dissertation is an effort towards estimating the lifetime of bypass diodes in field deployed modules, and therefore, reducing the uncertainty in long term reliability of PV modules.
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Date Issued: 2015
Identifier: CFE0006001, ucf:51023
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006001

Title: Mid-infrared plasmonics.
Creator: Khalilzadeh Rezaie, Farnood, Peale, Robert, Ishigami, Masa, Schoenfeld, Winston, Buchwald, Walter, Abdolvand, Reza, University of Central Florida
Abstract / Description: This dissertation reports investigations into materials for, and applications of, infrared surface plasmon polaritons (SPP). SPPs are inhomogeneous electromagnetic waves that are bound to the surface of a conductor. Tight confinement of electromagnetic energy, the primary virtue of SPPs for so-called (")plasmonic(") applications, requires plasma frequencies for the conductor near the intended infrared operational frequencies. This requires carrier concentrations that are much less than those...
Show moreThis dissertation reports investigations into materials for, and applications of, infrared surface plasmon polaritons (SPP). SPPs are inhomogeneous electromagnetic waves that are bound to the surface of a conductor. Tight confinement of electromagnetic energy, the primary virtue of SPPs for so-called (")plasmonic(") applications, requires plasma frequencies for the conductor near the intended infrared operational frequencies. This requires carrier concentrations that are much less than those of usual metals such as gold and silver. I have investigated the optical properties and SPP excitation resonances of two materials having infrared plasma frequencies, namely the semimetal bismuth and the transparent conducting fluorine-doped tin-oxide (FTO). The complex permittivity spectra for evaporated films of Bi were found to be distinctly different than earlier reports for crystal or polycrystalline films, and SPP excitation resonances on Bi-coated gratings were found to be disappointingly broad. Permittivity spectra for chemical spray deposited FTO were obtained to long-wave IR wavelengths for the first time, and nano-crystalline FTO-coated silicon lamellar gratings show remarkable conformity. SPP excitation resonances for FTO are more promising than for Bi. Thus, FTO appears to be a promising SPP host for infrared plasmonics, e.g. a planer waveguide plasmonic spectral sensor, whose design was elaborated and investigated as part of my research and which requires SPP-host coating on deep vertical side walls of a trench-like analyte interaction region. Additionally, FTO may serve as a useful conducting oxide for a near-IR plasmonic spectral imager that I have investigated theoretically.
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Date Issued: 2015
Identifier: CFE0006222, ucf:51080
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006222

Title: Performance optimization of lateral-mode thin-film piezoelectric-on-substrate resonant systems.
Creator: Fatemi, Hedy, Abdolvand, Reza, Sundaram, Kalpathy, Malocha, Donald, Gong, Xun, Cho, Hyoung Jin, University of Central Florida
Abstract / Description: The main focus of this dissertation is to characterize and improve the performance of thin-film piezoelectric-on-substrate (TPoS) lateral-mode resonators and filters. TPoS is a class of piezoelectric MEMS devices which benefits from the high coupling coefficient of the piezoelectric transduction mechanism while taking advantage of superior acoustic properties of a substrate. The use of lateral-mode TPoS designs allows for fabrication of dispersed-frequency filters on a single substrate, thus...
Show moreThe main focus of this dissertation is to characterize and improve the performance of thin-film piezoelectric-on-substrate (TPoS) lateral-mode resonators and filters. TPoS is a class of piezoelectric MEMS devices which benefits from the high coupling coefficient of the piezoelectric transduction mechanism while taking advantage of superior acoustic properties of a substrate. The use of lateral-mode TPoS designs allows for fabrication of dispersed-frequency filters on a single substrate, thus significantly reducing the size and manufacturing cost of devices. TPoS filters also offer a lower temperature coefficient of frequency, and better power handling capability compared to rival technologies all in a very small footprint.Design and fabrication process of the TPoS devices is discussed. Both silicon and diamond substrates are utilized for fabrication of TPoS devices and results are compared. Specifically, the superior acoustic properties of nanocrystalline diamond in scaling the frequency and energy density of the resonators is highlighted in comparison with silicon. The performance of TPoS devices in a variety of applications is reported. These applications include lateral-mode TPoS filters with record low IL values (as low as 2dB) and fractional bandwidth up to 1%, impedance transformers, very low phase noise oscillators, and passive wireless temperature sensors.
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Date Issued: 2015
Identifier: CFE0005945, ucf:50805
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005945

Title: Precision Metrology of Laser Plasmas in the XUV Band.
Creator: Szilagyi, John, Richardson, Martin, Sundaram, Kalpathy, Abdolvand, Reza, Baudelet, Matthieu, Shivamoggi, Bhimsen, University of Central Florida
Abstract / Description: The XUV band, a region of light spanning the wavelength range of 5 - 200 nm, is located between the Ultraviolet and X-ray regions of the electromagnetic spectrum. It is further divided into a 100 - 200 nm region called the Vacuum Ultraviolet (VUV), and a 5 (-) 100 nm region called the Extreme Ultraviolet (EUV). Applications of this light have been slow to develop due to the lack of suitable sources, efficient optics, and sensitive detectors. Recently, many industries such as the semiconductor...
Show moreThe XUV band, a region of light spanning the wavelength range of 5 - 200 nm, is located between the Ultraviolet and X-ray regions of the electromagnetic spectrum. It is further divided into a 100 - 200 nm region called the Vacuum Ultraviolet (VUV), and a 5 (-) 100 nm region called the Extreme Ultraviolet (EUV). Applications of this light have been slow to develop due to the lack of suitable sources, efficient optics, and sensitive detectors. Recently, many industries such as the semiconductor manufacturing industry, medical surgery, micromachining, microscopy, and spectroscopy have begun to benefit from the short wavelengths and the high photon energies of this light. At present, the semiconductor chip industry is the primary reason for the investment in, and development of, XUV sources, optics, and detectors. The demand for high power EUV light sources at 13.5 nm wavelength is driven by the development of the next generation of semiconductor lithography tools. The development of these tools enables the continued reduction in size, and the increase in transistor density of semiconductor devices on a single chip. Further development and investigation of laser produced plasma EUV light sources is necessary to increase the average optical power and reliability. This will lead to an increase in the speed of EUV lithographic processes, which are necessary for future generations of advanced chip design, and high volume semiconductor manufacturing. Micromachining, lithography, and microscopy benefit from improvements in resolution due to the shorter wavelengths of light in the VUV band. In order to provide adequate illumination for these applications, sources are required which are brighter and have higher average power. Laser produced plasma (LPP) VUV light sources are used extensively for lithography and defect detection in semiconductor manufacturing. Reductions in the wavelength and increases in the average power will increase the rate and yield of chip manufacture, as well as reduce the costs of semiconductor manufacture.The work presented in this thesis, describes the development of two laser plasma source facilities in the Laser Plasma Laboratory at UCF, which were designed to investigate EUV and VUV laser plasma sources. The HP-EUV-Facility was developed to optimize and demonstrate a high power 13.5 nm EUV LPP source. This facility provides high resolution spectroscopy across 10.5 - 20 nm, and absolute energy measurement of 13.5 nm +/- 2% in 2? sr. The VUV-MS-Facility was developed to investigate VUV emission characteristics of laser plasmas of various target geometries and chemistries. This facility provides absolute calibrated emission spectra for the 124 - 250 nm wavelength range, in addition to, at wavelength plasma imaging. Calibrated emission spectra, in-band power, and conversion efficiency are presented in this work for gas targets of Argon, Krypton, and Xenon and solid targets of Silicon, Copper, Molybdenum, Indium, Tantalum, Tin, and Zinc, across the laser intensity range of 8.0x10^6 (-) 3.2x10^12 W/cm2.
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Date Issued: 2017
Identifier: CFE0006805, ucf:51793
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006805

Title: The Effect of Morphology on Reflectance in Silicon Nanowires Grown by Electroless Etching.
Creator: Velez, Victor, Sundaram, Kalpathy, Kapoor, Vikram, Yuan, Jiann-Shiun, Abdolvand, Reza, Kar, Aravinda, University of Central Florida
Abstract / Description: The strong light trapping properties of Silicon Nanowires have attracted much interest in the past few years for the conversion of sun energy into conventional electricity. Studies have been completed for many researchers to reduce the cost of fabrication and reflectance of solar light in these nanostructures to make a cheaper and more efficient solar cell technology by using less equipment for fabrication and employing different materials and solution concentrations. Silver, a conducting and...
Show moreThe strong light trapping properties of Silicon Nanowires have attracted much interest in the past few years for the conversion of sun energy into conventional electricity. Studies have been completed for many researchers to reduce the cost of fabrication and reflectance of solar light in these nanostructures to make a cheaper and more efficient solar cell technology by using less equipment for fabrication and employing different materials and solution concentrations. Silver, a conducting and stable metal is used these days as a precursor to react with silicon and then form the nanowires. Its adequate selection of solution concentration for a size of silicon substrate and the treatment for post-cleaning of silver dendrites make it a viable method among the others. It is an aim of this research to obtain significant low reflectance across the visible solar light range. Detailed concentration, fabrication and reflectance studies is carried out on silicon wafer in order to expand knowledge and understanding.In this study, electroless etching technique has been used as the growth mechanism of SiNWs at room temperature. Optimum ratios of solution concentration and duration for different sizes of exposed area to grow tall silicon nanowires derived from experimentation are presented. Surface imaging of the structures and dimension of length and diameter have been determined by Scanner Electron Microscopy (SEM) and the reflectance in the optical range in silicon nanowires has been make using UV-Visible Spectrophotometer.
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Date Issued: 2017
Identifier: CFE0006815, ucf:51807
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006815

Title: Novel Photonic Resonance Arrangements Using Non-Hermitian Exceptional Points.
Creator: Hodaeiesfahani, Seyedhossein, Khajavikhan, Mercedeh, Christodoulides, Demetrios, Likamwa, Patrick, Abdolvand, Reza, University of Central Florida
Abstract / Description: In recent years, non-Hermitian degeneracies also known as exceptional points (EPs) have emerged as a new paradigm for engineering the response of optical systems. EPs can appear in a wide class of open non-Hermitian configurations. Among different types of non-conservative photonic systems, parity-time (PT) symmetric arrangements are of particular interest since they provide an excellent platform to explore the physics of exceptional points. In this work, the intriguing properties of...
Show moreIn recent years, non-Hermitian degeneracies also known as exceptional points (EPs) have emerged as a new paradigm for engineering the response of optical systems. EPs can appear in a wide class of open non-Hermitian configurations. Among different types of non-conservative photonic systems, parity-time (PT) symmetric arrangements are of particular interest since they provide an excellent platform to explore the physics of exceptional points. In this work, the intriguing properties of exceptional points are utilized to address two of the long standing challenges in the field of integrated photonics- enforcing single mode lasing in intrinsically multimode cavities and enhancing the sensitivity of micro-resonators.In the first part of this work, I will describe how stable single mode lasing can be readily achieved in longitudinally and transversely multi-moded microring cavities through the systematic utilization of abrupt phase transitions at exceptional points. This technique will be first demonstrated in a parity-time laser that is comprised of a gain cavity coupled to an identical but lossy counterpart. A detailed study of the behavior of this system around the exceptional point will be presented. Furthermore, we report the first experimental realization of a dark state laser in which by strategically designing the spectral locations of exceptional points, widely tunable single-mode lasing can be attained even at high pump levels. Despite the presence of loss in such open laser systems, the slope efficiency remains virtually intact. Our results demonstrate the potential of exceptional points as a versatile design tool for mode management in on-chip laser configurations.In the second part of my dissertation, I will show how the exceptional points and their underlying degeneracies can be used to significantly boost the intrinsic sensitivity of microcavities. I will demonstrate the enhanced sensitivity in a binary PT-symmetric coupled cavity arrangement that is biased at an exceptional point. Then I will report the first observation of higher-order exceptional points in a ternary parity-time symmetric microring laser system with a judiciously tailored gain-loss distribution. The enhanced response associated with this ternary system follows a cubic root dependence on externally introduced perturbation, which can in turn be detected in the spectral domain. Using such arrangements, more than one order of magnitude enhancement in the sensitivity is observed experimentally. These results can pave the way towards improving the performance of current on-chip micro-cavity sensors.
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Date Issued: 2017
Identifier: CFE0006947, ucf:51627
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006947

Title: Enhancement of Antenna Array Performance Using Reconfigurable Slot-Ring Antennas and Integrated Filter/Antennas.
Creator: Li, Tianjiao, Gong, Xun, Wahid, Parveen, Yuan, Jiann-Shiun, Abdolvand, Reza, Kuebler, Stephen, University of Central Florida
Abstract / Description: As modern communication system technology develops, the demand for devices with smaller size, higher efficiency, and more functionality has increased dramatically. In addition, highly integrated RF-front-end modules with a reduced footprint and less transition loss between cascaded devices are desirable in most advanced wireless communication systems. Antenna arrays are widely used in wireless communication systems due to their high directivity and beam steering capability. Moreover, antenna...
Show moreAs modern communication system technology develops, the demand for devices with smaller size, higher efficiency, and more functionality has increased dramatically. In addition, highly integrated RF-front-end modules with a reduced footprint and less transition loss between cascaded devices are desirable in most advanced wireless communication systems. Antenna arrays are widely used in wireless communication systems due to their high directivity and beam steering capability. Moreover, antenna arrays are preferred in mobile communication systems for diversity reception to reduce signal fading effects. In order to meet the various requirements of rapidly developing wireless communication systems, low cost, compact, multifunctional integrated antenna arrays are in high demand.Reconfigurable antennas that can flexibly adapt to different applications by dynamically changing their frequency and radiation properties have attracted a lot of attention. Frequency, radiation pattern, polarization, or a combination of two or more of these parameters in the reconfiguration of antennas was studied and presented in recent years. A single reconfigurable antenna is able to replace multiple traditional antennas and accomplish different tasks. Thus, the complexity of wireless communication systems can be greatly reduced with a smaller device size. On the other hand, the integration of antennas with other devices in wireless communication systems that can improve the efficiency and shrink the device size is a growing trend in antenna technology. Compact and highly efficient integrated filters and antennas were studied previously; the studies show that by seamlessly co-designing filters with patch antennas, the fractional bandwidth (FBW) of the antennas can be enhanced as compared to stand-alone antennas.However, the advantages of both the reconfigurable antenna and integrated filter/antenna technology have not been fully applied to antenna array applications. Therefore, this dissertation explores how to maximize the antenna array performance using reconfigurable antennas and integrated filter/antennas. A continuously frequency reconfigurable slot-ring antenna/array with switches and varactors is presented first. By changing the state of the loaded switches, the reconfigurable slot-ring antenna/array is able to operate as an L-band slot-ring antenna or a 2(&)#215;2 S-band slot-ring antenna array. In each frequency band, the operation frequency of the antenna/array can be continuously tuned with the loaded varactors. To further enhance the functionality of the reconfigurable slot-ring antenna array, a dual-polarized fractal-shaped reconfigurable slot-ring antenna/array is developed with a reduced number of switches and an increased FBW. Additionally, ground plane solutions are explored to achieve single-sided radiation. The benefits of filter/antenna integration are also investigated in both linearly polarized patch phased arrays and circularly polarized patch antenna arrays. Finally, a preliminary study of a tunable integrated evanescent mode filter/antenna is conducted to validate the concept of combining reconfigurable antennas and integrated filter/antennas.
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Date Issued: 2017
Identifier: CFE0006950, ucf:51661
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006950

MEMS (3)	+ -
Filter (2)	+ -
Infrared (2)	+ -
Piezoelectric (2)	+ -
Resonator (2)	+ -

metrology (2)	+ -
2D materials (1)	+ -
3rd harmonic GUDT (1)	+ -
3rd harmonic SPUDT (1)	+ -
AM-BPSK (1)	+ -
Accelerated Test (1)	+ -
Antenna (1)	+ -
Array (1)	+ -
BPSK (1)	+ -
BUBBLE DYNAMICS (1)	+ -
BaTiO3 (1)	+ -
Beam steering (1)	+ -
Black silicon (1)	+ -
Bypass Diode (1)	+ -
CDMA (1)	+ -
DFM (1)	+ -
Deposition (1)	+ -
Diamond (1)	+ -
EUV (1)	+ -
EUVL (1)	+ -
Electroless Metal Deposition (1)	+ -
Heat Transfer Coefficient (1)	+ -
Integration (1)	+ -
Low-power computation (1)	+ -
MEMS Resonators (1)	+ -

ETD Collection (21)	+ -
Honors Collection (1)	+ -

Abdolvand, Reza (22)	+ -
University of Central Florida (22)	+ -
Sundaram, Kalpathy (10)	+ -
Gong, Xun (5)	+ -
Yuan, Jiann-Shiun (5)	+ -

Kapoor, Vikram (3)	+ -
Kuebler, Stephen (3)	+ -
Malocha, Donald (3)	+ -
Schoenfeld, Winston (3)	+ -
Wahid, Parveen (3)	+ -
Cho, Hyoung Jin (2)	+ -
Christodoulides, Demetrios (2)	+ -
Kar, Aravinda (2)	+ -
Khajavikhan, Mercedeh (2)	+ -
Likamwa, Patrick (2)	+ -
Peale, Robert (2)	+ -
Peles, Yoav (2)	+ -
Alhasan, Sarmad (1)	+ -
Atia, George (1)	+ -
Bakhshi, Sara (1)	+ -
Baudelet, Matthieu (1)	+ -
Buchwald, Walter (1)	+ -
Davis, Kristopher (1)	+ -
DeMara, Ronald (1)	+ -
Del Barco, Enrique (1)	+ -
Fan, Deliang (1)	+ -
Fatemi, Hedy (1)	+ -
Georgiopoulos, Michael (1)	+ -
Gou, Jihua (1)	+ -
Hayenga, William (1)	+ -

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