Electromagnetics and Photonics Commons^™

Transparent Antennas For Solar Cell Integration, Tursunjan Yasin

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Transparent patch antennas have a certain level of optical transparency. Highly transparent patch antennas can be integrated with the solar panels of small satellites, which are becoming increasingly important in space exploration. Traditional patch antennas, which are not transparent, are employed on small satellites and compete with solar cells for surface area. But a transparent patch antenna can be placed directly on top of the solar cells and alleviate the issue of limited surface real estate. For such an integration, a high optical transparency of the patch antenna is required from the solar cells’ point of view since the solar …

Study Of A Non-Equilibrium Plasma Pinch With Application For Microwave Generation, Ahmad Al Agry

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Non-Equilibrium Plasma Pinch (NEPP), also known as the Dense Plasma Focus (DPF) is well known as a source of energetic ions, relativistic electrons and neutrons as well as electromagnetic radiation extending from the infrared to X-ray. In this dissertation, the operation of a 15 kJ, Mather type, NEPP machine is studied in detail. A large number of experiments are carried out to tune the machine parameters for best performance using helium and hydrogen as filling gases. The NEPP machine is modified to be able to extract the copious number of electrons generated at the pinch. A hollow anode with …

Metamaterial Enhanced Wireless Power Transmission System, Travis Jade Heffernan

Master's Theses

Nikolai Tesla's revolutionary experiments demonstrated the possible benefits of transmitting power wirelessly as early as 1891. Applications for the military, consumers, emergency personnel, remote sensors, and others use Tesla’s discovery of wireless power. Wireless power transmission (WPT) has the potential to be a common source of consumable energy, but it will only receive serious consideration if the transmit and receive systems are extremely efficient and capable of delivering usable amounts of power. Research has been conducted to improve the efficiency and performance of nearly every aspect of WPT systems, but the relatively new field of metamaterials (MTMs) has yet to …

Investigating The Possible Sources Of Error Using The Method Of Moments To Solve A Dielectric Scattering Problem, Phillip D. Bishop

Master's Theses (2009 -)

In an electromagnetic scattering problem, an incoming electromagnetic wave interacts with an object. The object is typically located in some medium, such as free space. When this electromagnetic wave becomes incident upon the object, the wave scatters. The goal of this work is to analyze the scattered fields for three different incoming wave types: a plane wave, a monopole line source, and a multipole line source. Each source is incident on an infinitely long circular cylinder of lossless dielectric material. Each source has a unique scattering characteristic.

The volume equivalence principle is used to replace the object geometry with mathematically …

Design, Fabrication, And Testing Of An Emr Based Orbital Debris Impact Testing Platform, Jeffrey J. Maniglia Jr.

Master's Theses

This paper describes the changes made from Cal Poly’s initial railgun system, the Mk. 1 railgun, to the Mk. 1.1 system, as well as the design, fabrication, and testing of a newer and larger Mk. 2 railgun system. The Mk. 1.1 system is developed as a more efficient alteration of the original Mk. 1 system, but is found to be defective due to hardware deficiencies and failure, as well as unforeseen efficiency losses. A Mk. 2 system is developed and built around donated hardware from the Naval Postgraduate School. The Mk. 2 system strove to implement an efficient, augmented, electromagnetic …

Characterization And Modeling Of An O-Band 1310 Nm Sampled-Grating Distributed Bragg Reflector (Sg-Dbr) Laser For Optical Coherence Tomography (Oct) Applications, Desmond Charles Talkington

Master's Theses

In this project, the performance aspects of a new early generation 1310 nm Sampled-Grating Distributed Bragg Reflector (SG-DBR) semiconductor laser are investigated. SG-DBR lasers are ideal for Source Swept Optical Coherence Tomography (SS-OCT), a Fourier-Domain based approach for OCT, necessitating a tunable wavelength source. Three internal sections control the frequency output for tuning, along with two amplifiers for amplitude control. These O-band SG-DBR devices are now being produced in research quantities. SG-DBR lasers have been produced at 1550 and 1600 nm for some times. Fundamental questions regarding the performance of the 1310 nm devices must be quantified. Standard metrics including …

Early Wildfire Detection Using Temporal Filtering And Multi-Band Infrared Analysis, Ansel John Boynton

Master's Theses

Every year wildfires threaten or destroy ecological habitats, man-made infrastructure and people’s lives. Additionally millions of dollars are spent each year trying to prevent and control these fires. Ideally if a wildfire can be detected before it rages out of control it can be extinguished and avoid large scale devastation. Traditional manned fire lookout towers are neither cost effective nor particularly efficient at detecting wildfire. It is proposed that temporal filtering can be used to isolate the signals created at the beginnings of potential wildfires. Temporal filtering can remove any background image and any periodic signals created by the camera …

A Novel Unit Cell Antenna For Highly Integrated Phased Arrays In The Shf Band, Timothy Bryan Ogilvie

Master's Theses

Phased arrays are electromagnetic antenna systems comprised of many radiating elements and processing electronics. Radiating elements are typically positioned in an orderly grid within the antenna aperture. In the receive mode of operation, radiating elements capture some of the signal energy from incoming radiation and guide these signals to processing electronics. Signals are filtered and amplified to maintain the desired sensitivity and complexly weighted using circuits with reconfigurable amplification gain and phase delay. Finally, all signals are combined. The summation of these complexly weighted spatial samples forms a spatial filter in the same way complexly weighted temporal samples establish a …

Nanowire Metal-Insulator-Metal Plasmonic Devices, Joseph W. Haus, Li Li, Cong Deng, Nkorni Katte, Michael Scalora, Domenico De Ceglia, Maria Antonietta Vincenti

Electro-Optics and Photonics Faculty Publications

In this paper we theoretically study the responsivity of Metal-Insulator-Metal nanostructures to light illumination over a broad wavelength band (1 - 25 microns) and we examine the role of a local field enhancement and electrostatic field on the responsivity.

Plasmonic Nanostructures For The Absorption Enhancement Of Silicon Solar Cells, Nathan Matthias Burford

Graduate Theses and Dissertations

In this work, computational investigation of plasmonic nanostructures was conducted using the commercial finite element electromagnetics solver Ansys® HFSS. Arrays of silver toroid nanoparticles located on the surface of an amorphous silicon thin-film absorbing layer were studied for particle sizes ranging from 20 nm to 200 nm in outer diameter. Parametric optimization by calculating an approximation of the photocurrent enhancement due to the nanoparticles was performed to determine optimal surface coverage of the nanoparticles. A comparison was made between these optimized nanotoroid arrays and optimized nanosphere arrays based on spectral absorption enhancement and potential photocurrent enhancement in an amorphous silicon …

Thermo-Piezo-Electro-Mechanical Simulation Of Algan (Aluminum Gallium Nitride) / Gan (Gallium Nitride) High Electron Mobility Transistor, Lorin E. Stevens

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Due to the current public demand of faster, more powerful, and more reliable electronic devices, research is prolific these days in the area of high electron mobility transistor (HEMT) devices. This is because of their usefulness in RF (radio frequency) and microwave power amplifier applications including microwave vacuum tubes, cellular and personal communications services, and widespread broadband access. Although electrical transistor research has been ongoing since its inception in 1947, the transistor itself continues to evolve and improve much in part because of the many driven researchers and scientists throughout the world who are pushing the limits of what modern …

Determination Of Ionospheric Current Systems By Measuring The Phase Shift On Amateur Satellite Frequencies, Prajwal M. Kasturi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Linearly polarized electromagnetic waves traveling through cold magnetized plasma experience Faraday rotation. The Appleton Hartree dispersion equation relates the phase shift on any electromagnetic ray to the magnetic field B, ion-electron density N_e and the angle the ray makes with the instantaneous magnetic field. This work uses the dispersion relation to calculate small time scale magnetic perturbations in the ionosphere due to electrojet current systems. The ionosphere is modeled as a collision free cold plasma with synthesized small scale magnetic perturbations. The work presented here simulates test cases, where the satellites transmits three amateur satellite radio band frequencies …

Reversible Mn Segregation At The Polar Surface Of Lithium Tetraborate, Christina L. Dugan, Robert L. Hengehold, Stephen R. Mchale, Juan A. Colon Santana, John W. Mcclory, Volodymyr T. Adamiv, Yaroslav V. Burak, Ya B. Losovyj, Peter A. Dowben

Faculty Publications

We find Mn surface segregation for single crystals of Mn doped Li₂B₄O₇, nominally Li_1.95Mn_0.05B₄O₇(001), but as the temperature increases, evidence of this Mn surface segregation diminishes significantly. At room temperature, the surface photovoltaic charging is significant for this pyroelectric material but is quenched at a temperature well below that seen for the undoped Li₂B₄O₇ samples. The suppression of surface charging in the region of 120 °C that accompanies the temperature of Mn dissolution in the bulk of Li₂B_{4 …}

Photoacoustic Detection Of Terahertz Radiation For Chemical Sensing And Imaging Applications, Stjepan Blazevic

Theses and Dissertations

The main research objective is the development of photoacoustic sensor capable of detecting weak terahertz (THz) electromagnetic radiation. The feasibility of THz remote sensing is seen in the utilization of Microelectromechanical systems (MEMS) cantilever-based sensor. The overall sensing functionality of the detector in development is based on the photoacoustic spectroscopy and direct piezoelectric effect phenomena, as a result of which significant part of investigation has been conducted in the areas of terahertz electromagnetic radiation and its detection. The main focus of this research work was the detector analytical and Finite Element Method (FEM) simulation modeling, involving necessary material properties investigations …

Constitutive Parameter Measurement Using Double Ridge Waveguide, Nathan J. Lehman

Theses and Dissertations

Electromagnetic materials characterization is important in the design of systems that interact with electromagnetic waves. Determining the constitutive parameters of a material is a vast area of research and practice. For this paper, discussion will focus on a destructive method using waveguides in the frequency range of 6-18 GHz. Traditional methods to perform similar measurements include using coaxial cable, stripline, focus beam and rectangular waveguides. This work will use Double Ridged Waveguide (DRWG) to compare to these other methods and will discuss the attributes and drawbacks of this new approach. The most similar method utilizes rectangular waveguide, so the primary …

Examining The Validity Of Using A Gaussian Schell-Model Source To Model The Scattering Of A Fully Coherent Gaussian Beam From A Rough Impedance Surface, Santasri Basu, Milo W. Hyde Iv, Salvatore J. Cusumano, Michael A. Marciniak, Steven T. Fiorino

Faculty Publications

Military applications that use adaptive optics (AO) often require a point source beacon at the target to measure and correct for wavefront aberrations introduced by atmospheric turbulence. However, turbulence prevents the formation of such a point beacon. The extended beacons that are created instead have finite spatial extents and exhibit varying degrees of spatial coherence. Modeling these extended beacons using a Gaussian Schell-model (GSM) form for the autocorrelation function would be a convenient approach due to the analytical tractability of Gaussian functions. We examine the validity of using such a model by evaluating the field scattered from a rough impedance …

Thermal And Electrical Transport In Ferromagnetic Metal Thin Films, Azure D. Avery

Electronic Theses and Dissertations

The recent emergence of spin caloritronics has focused considerable attention on the interplay between spin, charge, and temperature gradients in magnetic materials. A reliable and energy efficient method for generating pure spin currents would signify an important step toward future spin-based nano-electronics that may offer lower power consumption and greater processing capabilities. To develop new technology using thermoelectric effects in magnetic thin films, it is essential to understand thermal and electrical transport through these films. One possible source of pure spin currents is the so-called spin Seebeck effect (SSE) in which a thermal gradient (∇T) applied to a ferromagnet is …

Biparametric Analyses Of Charge Trapping In Cd0.9Zn0.1Te Based Virtual Frisch Grid Detectors, S. K. Chaudhuri, K. J. Zavalla, R. M. Krishna, K. C. Mandal

Faculty Publications

No abstract provided.

3-D Terahertz Synthetic-Aperture Imaging And Spectroscopy, Samuel C. Henry

Dissertations and Theses

Terahertz (THz) wavelengths have attracted recent interest in multiple disciplines within engineering and science. Situated between the infrared and the microwave region of the electromagnetic spectrum, THz energy can propagate through non-polar materials such as clothing or packaging layers. Moreover, many chemical compounds, including explosives and many drugs, reveal strong absorption signatures in the THz range. For these reasons, THz wavelengths have great potential for non-destructive evaluation and explosive detection. Three-dimensional (3-D) reflection imaging with considerable depth resolution is also possible using pulsed THz systems. While THz imaging (especially 3-D) systems typically operate in transmission mode, reflection offers the most …

Insertion Of Lithium Ions Into Tio2 (Rutile) Crystals: An Electron Paramagnetic Resonance Study Of The Li-Associated Ti3+ Small Polaron, A. T. Brant, Nancy C. Giles, Larry E. Halliburton

Faculty Publications

Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) are used to identify a Ti³⁺-Li⁺ complex in TiO₂ crystals having the rutile structure. This defect consists of an interstitial Li⁺ ion adjacent to a substitutional Ti³⁺ ion (the unpaired electron on the Ti³⁺ ion provides charge compensation for the Li⁺ ion). The neutral Ti³⁺-Li⁺ complex is best described as a donor-bound small polaron and is similar in structure to the recently reported neutral fluorine and hydrogen donors in TiO₂ (rutile). Lithium ions are diffused into the crystals at …