Design And Analysis Of Circularly Polarized Electrically Small Antennas,
2014
Georgia Southern University
Design And Analysis Of Circularly Polarized Electrically Small Antennas, Jesse R. Ludwig
College of Graduate Studies: Theses & Dissertations
A growing need for efficient wireless communication is prevalent in the world in which we live. From cell phones to television to GPS applications, wireless communications are vital in consumer electronics and military applications. In these applications, a miniaturized antenna is sometimes necessary for reducing overall size of the communication system. For many satellite based communication applications, circular polarization in antennas is needed for efficient communication. In this thesis, the miniaturization technique known as T-top loading is utilized on two novel antenna designs. One design is an electrically small, circularly polarized planar cross dipole and the other design is a …
Reconfigurable Microstrip Antennas With Tunable Radiation Pattern Characteristics,
2014
University of Mississippi
Reconfigurable Microstrip Antennas With Tunable Radiation Pattern Characteristics, Ahmed Khidre
Electronic Theses and Dissertations
Reconfigurable beam antenna systems are capable of changing their radiation characteristics in real time, such as beam direction, beam shape, beamwidth, etc. Such antenna system is desired for various wireless applications because of many reasons among them; it helps to enhance signal strength received from an intended target, mitigates interference, and accommodates sudden changes in traffic demand of wireless networks. It might also help to reduce the deployment cost of wireless networks infrastructures. In this dissertation, designs for reconfigurable beam microstrip antennas with tunable radiation characteristics have been proposed. The method to achieve these designs is the reconfigurable parasitic element …
Modification Of Plasmonic Nano Structures' Absorption And Scattering Under Evanescent Wave Illumination Above Optical Waveguides Or With The Presence Of Different Material Nano Scale Atomic Force Microscope Tips,
2014
University of Kentucky
Modification Of Plasmonic Nano Structures' Absorption And Scattering Under Evanescent Wave Illumination Above Optical Waveguides Or With The Presence Of Different Material Nano Scale Atomic Force Microscope Tips, Gazi Mostafa Huda
Theses and Dissertations--Electrical and Computer Engineering
The interaction of an evanescent wave and plasmonic nanostructures are simulated in Finite Element Method. Specifically, the optical absorption cross section (Cabs) of a silver nanoparticle (AgNP) and a gold nanoparticle (AuNP) in the presence of metallic (gold) and dielectric (silicon) atomic force microscope (AFM) probes are numerically calculated in COMSOL. The system was illuminated by a transverse magnetic polarized, total internally reflected (TIR) waves or propagating surface plasmon (SP) wave. Both material nanoscale probes localize and enhance the field between the apex of the tip and the particle. Based on the absorption cross section equation the author …
Broadband Approaches And Beam-Scanning Techniques For Reflectarray Antenna,
2014
University of Mississippi
Broadband Approaches And Beam-Scanning Techniques For Reflectarray Antenna, Yilin Mao
Electronic Theses and Dissertations
Reflectarray antennas combine the numerous advantages of reflector antennas and phased array antennas and create a hybrid high-gain antenna with a low-profile, low-mass, easy-fabrication, and diversified radiation performance. However, it still has some inherent drawbacks, such as limited bandwidth and scanning range, which are targeted in this dissertation. At first, the array theory approach for radiation analysis of reflectarray antennas is described and implemented. Numerical results are then presented and compared with reference results to confirm its reliability. As the most critical influential factor to the reflectarray bandwidth, the element bandwidth was studied at first, and the effects of element …
Analysis And Design Of Low Profile Multiband Multifunctional Antenna Arrays,
2014
University of Mississippi
Analysis And Design Of Low Profile Multiband Multifunctional Antenna Arrays, Walker F. Hunsicker
Electronic Theses and Dissertations
Light-weight phased array antennas for aerospace and mobile applications require utilizing the same antenna aperture to provide multiple functions with dissimilar radiation pattern specifications (e.g., multiband operation for communications and tracking). Multi-functional antennas provide advantages over aggregate antenna clusters by reducing space requirements, and can aid in the optimal placement of all required apertures to provide adequate isolation between channels. Furthermore, the combination of antenna apertures into a comgeometry mitigates co-site installation issues by addressing interference within the integrated radiator design itself as opposed to the extensive analysis which is required to configure multiple radiators in close proximity. The combination …
3d Printed Electromagnetic Transmission And Electronic Structures Fabricated On A Single Platform Using Advanced Process Integration Techniques,
2014
University of Texas at El Paso
3d Printed Electromagnetic Transmission And Electronic Structures Fabricated On A Single Platform Using Advanced Process Integration Techniques, Paul I. Deffenbaugh
Open Access Theses & Dissertations
3D printing has garnered immense attention from many fields including in-office rapid prototyping of mechanical parts, outer-space satellite replication, garage functional firearm manufacture, and NASA rocket engine component fabrication. 3D printing allows increased design flexibility in the fabrication of electronics, microwave circuits and wireless antennas and has reached a level of maturity which allows functional parts to be printed. Much more work is necessary in order to perfect the processes of 3D printed electronics especially in the area of automation. Chapter 1 shows several finished prototypes of 3D printed electronics as well as newly developed techniques in fabrication. Little is …
Self-Heating Control Of Edge Emitting And Vertical Cavity Surface Emitting Lasers,
2014
University of Central Florida
Self-Heating Control Of Edge Emitting And Vertical Cavity Surface Emitting Lasers, Yu Zhang
Electronic Theses and Dissertations
Self-heating leads to temperature rise of laser diode and limits the output power, efficiency and modulation bandwidth due to increased loss and decreased differential gain. The main heat sources in laser diode during continuous wave operation are Joule heating and free carrier absorption loss. To control device self-heating, the epi structure needs to be designed with low electrical resistance and low absorption loss, while the heat flux must spread out of the device efficiently. This dissertation presents the control of self-heating of both edge emitting laser diodes and vertical cavity surface emitting lasers (VCSELs). For the 980nm high power edge …
Particle Manipulation Via Optical Forces And Engineering Soft-Matter Systems With Tunable Nonlinearities.,
2014
University of Central Florida
Particle Manipulation Via Optical Forces And Engineering Soft-Matter Systems With Tunable Nonlinearities., Shima Fardad
Electronic Theses and Dissertations
One of the most intriguing properties of light-matter interaction is the ability of an electromagnetic field to exert mechanical forces on polarizable objects. This phenomenon is a direct consequence of the fact that light carries momentum, which in turn can be transferred to matter. Mediated by scattering, this interaction usually manifests itself as a “pushing force” in the direction of beam propagation. However, it is possible to judiciously engineer these optical forces, either by tailoring particle polarizability, and/or by structuring the incident light field. As a simple example, a tightly focused laser beam demonstrates strong gradient forces, which may attract …
Frequency Selective Detection Of Infrared Radiation In Uncooled Optical Nano-Antenna Array,
2014
University of Central Florida
Frequency Selective Detection Of Infrared Radiation In Uncooled Optical Nano-Antenna Array, Sushrut Modak
Electronic Theses and Dissertations
Mid-infrared (mid-IR) detection and imaging over atmospheric transparent 3-5 μm and 8-12 μm bands are increasingly becoming important for various space, defense and civilian applications. Various kinds of microbolometers offer uncooled detection of IR radiation. However, broadband absorption of microbolometers makes them less sensitive to spectrally resolved detection of infrared radiation and the fabrication is also very tedious involving multiple complex lithography steps. In this study, we designed an optical nano-antenna array based detector with narrow frequency band of operation. The structure consists of a two-element antenna array comprised of a perforated metallic hole array coupled with an underneath disk …
Nonlinear Integrated Photonics On Silicon And Gallium Arsenide Substrates,
2014
University of Central Florida
Nonlinear Integrated Photonics On Silicon And Gallium Arsenide Substrates, Jichi Ma
Electronic Theses and Dissertations
Silicon photonics is nowadays a mature technology and is on the verge of becoming a blossoming industry. Silicon photonics has also been pursued as a platform for integrated nonlinear optics based on Raman and Kerr effects. In recent years, more futuristic directions have been pursued by various groups. For instance, the realm of silicon photonics has been expanded beyond the well-established near-infrared wavelengths and into the mid-infrared (3 - 5 µm). In this wavelength range, the omnipresent hurdle of nonlinear silicon photonics in the telecommunication band, i.e., nonlinear losses due to two-photon absorption, is inherently nonexistent. With the lack of …
Specialty Fiber Lasers And Novel Fiber Devices,
2014
University of Central Florida
Specialty Fiber Lasers And Novel Fiber Devices, Clemence Jollivet
Electronic Theses and Dissertations
At the Dawn of the 21st century, the field of specialty optical fibers experienced a scientific revolution with the introduction of the stack-and-draw technique, a multi-steps and advanced fiber fabrication method, which enabled the creation of well-controlled micro-structured designs. Since then, an extremely wide variety of finely tuned fiber structures have been demonstrated including novel materials and novel designs. As the complexity of the fiber design increased, highly-controlled fabrication processes became critical. To determine the ability of a novel fiber design to deliver light with properties tailored according to a specific application, several mode analysis techniques were reported, addressing the …
Lp Fiber Mode Converters Using Holographic Phase Mask In Photo-Thermo-Refractive Glass,
2014
University of Central Florida
Lp Fiber Mode Converters Using Holographic Phase Mask In Photo-Thermo-Refractive Glass, Aniket Patil
Electronic Theses and Dissertations
In this study, an investigation was undertaken to research the use of holographic phase masks (HPMs) in photo-thermo-refractive (PTR) glass as mode converters for linearly polarized (LP) fiber modes. A Spatial Light Modulator (SLM) was used to generate higher-order transverse fiber modes LPm,n. Under proper incidence condition on the holographic device, LPm,n modes are diffracted and simultaneously converted into higher order or lower order LP modes. The process was analyzed by imaging the far field on a CCD camera. It is demonstrated that using this novel method of converting transverse fiber modes several combinations of LP modes can be converted …
Advanced Liquid Crystal Materials For Display And Photonic Applications,
2014
University of Central Florida
Advanced Liquid Crystal Materials For Display And Photonic Applications, Yuan Chen
Electronic Theses and Dissertations
Thin-film-transistor (TFT) liquid crystal display (LCD) has been widely used in smartphones, pads, laptops, computer monitors, and large screen televisions, just to name a few. A great deal of effort has been delved into wide viewing angle, high resolution, low power consumption, and vivid color. However, relatively slow response time and low transmittance remain as technical challenges. To improve response time, several approaches have been developed, such as low viscosity liquid crystals, overdrive and undershoot voltage schemes, thin cell gap with a high birefringence liquid crystal, and elevated temperature operation. The state-of-the-art gray-to-gray response time of a nematic LC device …
Generation And Characterization Of Sub-70 Isolated Attosecond Pulses,
2014
University of Central Florida
Generation And Characterization Of Sub-70 Isolated Attosecond Pulses, Qi Zhang
Electronic Theses and Dissertations
Dynamics occurring on microscopic scales, such as electronic motion inside atoms and molecules, are governed by quantum mechanics. However, the Schroedinger equation is usually too complicated to solve analytically for systems other than the hydrogen atom. Even for some simple atoms such as helium, it still takes months to do a full numerical analysis. Therefore, practical problems are often solved only after simplification. The results are then compared with the experimental outcome in both the spectral and temporal domain. For accurate experimental comparison, temporal resolution on the attosecond scale is required. This had not been achieved until the first demonstration …
High Performance Three-Dimensional Display Based On Polymer-Stabilized Blue Phase Liquid Crystal,
2014
University of Central Florida
High Performance Three-Dimensional Display Based On Polymer-Stabilized Blue Phase Liquid Crystal, Yifan Liu
Electronic Theses and Dissertations
Autostereoscopic 2D/3D (two-dimension/three-dimension) switchable display has been attracting great interest in research and practical applications for several years. Among different autostereoscopic solutions, direction-multiplexed 3D displays based on microlens array or parallax barrier are viewed as the most promising candidates, due to their compatibility with conventional 2D display technologies. These 2D/3D switchable display system designs rely on fast switching display panels and photonics devices, including adaptive focus microlens array and switchable slit array. Polymer-stabilized blue phase liquid crystal (PS-BPLC) material provides a possible solution to meet the aforementioned fast response time requirement. However, present display and photonic devices based on blue …
Holographic Recording And Applications Of Multiplexed Volume Bragg Gratings In Photo-Thermo-Refractive Glass,
2014
University of Central Florida
Holographic Recording And Applications Of Multiplexed Volume Bragg Gratings In Photo-Thermo-Refractive Glass, Daniel Ott
Electronic Theses and Dissertations
Recent developments in holographic recording of volume Bragg gratings (VBGs) in photo-thermo-refractive (PTR) glass have demonstrated their utility as components in high power laser systems for spectral narrowing, transverse mode control, beam combining, and pulse stretching/compression. VBG structures are capable of diffracting incident light into a single diffraction order with high efficiency given the Bragg condition is met. The Bragg condition depends on both the wavelength and angle of the incident light making VBGs useful for filtering and manipulating both the wavelength and angular spectrum of a source. This dissertation expands upon previous research in PTR VBGs by investigating multiplexed …
Entangled Photon Pairs In Disordered Photonic Lattices,
2014
University of Central Florida
Entangled Photon Pairs In Disordered Photonic Lattices, Lane Martin
Electronic Theses and Dissertations
Photonic lattices consisting of arrays of evanescently coupled waveguides fabricated with precisely controlled parameters have enabled the study of discrete optical phenomena, both classical and quantum, and the simulation of other physical phenomena governed by the same dynamics. In this dissertation, I have experimentally demonstrated transverse Anderson localization of classical light in arrays with off-diagonal coupling disorder and investigated theoretically and experimentally the propagation of entangled photon pairs through such disordered systems. I discovered a new phenomenon, Anderson co-localization, in which a spatially entangled photon pair in a correlated transversally extended state localizes in the correlation space, though neither photon …
Translation Of 'Seasons Of Life: A Panoramic Selection Of Songs By Rabindranath Tagore',
2014
University of Dayton
Translation Of 'Seasons Of Life: A Panoramic Selection Of Songs By Rabindranath Tagore', Monish Ranjan Chatterjee
Electrical and Computer Engineering Faculty Publications
No abstract provided.
Shielding Effectiveness (Se) Measurement For Maxair Waveguide Panel, Lossy Material Evaluation By Laptop Application,
2014
Missouri University of Science and Technology
Shielding Effectiveness (Se) Measurement For Maxair Waveguide Panel, Lossy Material Evaluation By Laptop Application, Xiao Li
Masters Theses
"The first part of the thesis presents the EM shielding effectiveness (SE) measurement of new kind of waveguide panel, MaxAir, which based on metal coating technology. SE Measurement tell the SE performance of MaxAir compared to the traditional metal waveguide panel. In terms of good features such as lower price, less weight, MaxAir could replace traditional waveguide panel in some applications by its SE results. There are two SE measurement methods are performed for MaxAir panel, both of them based on reverberation chamber. Measured SE for several MaxAir panel samples in different cell dimension and coating configuration. By the Measured …
Cable Discharge Events (Cde) -- A Modeling And Simulation Perspective,
2014
Missouri University of Science and Technology
Cable Discharge Events (Cde) -- A Modeling And Simulation Perspective, Viswa Pilla
Masters Theses
"Cable discharge events (CDE) typically occur when a charged cable is connected to an electronic device. Several CDE damages in Ethernet LAN and USB communication interface equipment are reported by the IC manufacturers. CDE differs from other types of ESD such as human body model (HBM), charged device model (CDM) and IEC 61000-4-2 mainly due to faster rise times, longer pulse widths and higher peak currents. Various factors such as cable geometries, charging and discharging mechanisms, and load conditions influence CDE. Several researchers have developed some measurement techniques to understand CDE waveforms. However, there is little information regarding its modeling …
