Doctor of Philosophy, The Ohio State University, 2018, Computer Science and Engineering

Distributed scientific array data is becoming more prevalent, increasing in size, and there is a growing need for (performance in) advanced analytics over these data. In this dissertation, we focus on addressing issues to allow data management, efficient declarative querying, and advanced analytics over array data. We formalize the semantic of array data querying, and introduce distributed querying abilities over these data. We show how to improve the optimization phase of join querying, while developing efficient methods to execute joins in general. In addition, we introduce a class of operations that is closely related to the traditional joins performed on relational tables - including an operation we refer to as Mutual Range Joins(MRJ), which arises on scientific data that is not only numerical, but also have measurement noise. While working closely with our colleagues to provide them usable analytics over array data, we uncovered a new type of analytical querying - analytics over windows with an inner window ordering (in contrast to the external window ordering, available elsewhere). Last, we adjust our join optimization approach for skewed settings, addressing resource skew observed in real environments as well as data skew that arises while data is processed. Several major contributions are introduced throughout this dissertation. First we formalize querying over scientific array data (basic operators, such as subsettings, as well as complex analytical functions and joins). We focus on distributed data, and present a framework to execute queries over variables that are distributed across multiple containers (DSDQuery DSI) - this framework is used in production environments. Next, we present an optimization approach for join queries over geo-distributed data. This approach considers networking properties such as throughput and latency to optimize the execution of join queries. For such complex optimization, we introduce methods and algorit (open full item for complete abstract)

Committee: Gagan Agrawal (Advisor); Arnab Nandi (Committee Member); P Sadayappan (Committee Member) Subjects: Computer Science

Master of Science in Engineering (MSEgr), Wright State University, 2010, Electrical Engineering

This thesis explores the use of wide band log periodic dipole array (LPDA) antennas in direction finding systems. A wide band log periodic antenna will be constructed and tested to ensure hardware capability. A novel approach utilizing non-uniform spacing in a linear array will be used to improve the spatial resolution of the direction finding system. These specialized linear arrays are known as minimum redundancy or non-redundant linear arrays.

Committee: Ray Siferd PhD (Committee Chair); Ronald Riechers PhD (Committee Member); Saiyu Ren PhD (Committee Member); Marian Kazimierczuk PhD (Committee Member); John Bantle PhD (Committee Member); Kefu Xue PhD (Other) Subjects: Electrical Engineering

Doctor of Philosophy, The Ohio State University, 2011, Electrical and Computer Engineering

There is strong interest to combine many antenna functionalities within a single, wideband aperture. However, size restrictions and conformal installation requirements are major obstacles to this goal (in terms of gain and bandwidth). Of particular importance is bandwidth; which, as is well known, decreases when the antenna is placed closer to the ground plane. Hence, recent efforts on EBG and AMC ground planes were aimed at mitigating this deterioration for low-profile antennas. In this dissertation, we propose a new class of tightly coupled arrays (TCAs) which exhibit substantially broader bandwidth than a single patch antenna of the same size. The enhancement is due to the cancellation of the ground plane inductance by the capacitance of the TCA aperture. This concept of reactive impedance cancellation was motivated by the ultrawideband (UWB) current sheet array (CSA) introduced by Munk in 2003. We demonstrate that as broad as 7:1 UWB operation can be achieved for an aperture as thin as λ/17 at the lowest frequency. This is a 40% larger wideband performance and 35% thinner profile as compared to the CSA. Much of the dissertation's focus is on adapting the conformal TCA concept to small and very low-profile finite arrays. Three particular designs are presented. One is a 6x6 patch array occupying a λ/3 x λ/3 small aperture (mid-frequency is at 2.1 GHz). Remarkably, it is only λ/42 thick yet delivers 5.6% impedance bandwidth (|S11| < -10dB), 4.4dB realized gain (87% efficiency) and 23% gain bandwidth (3dB drop). The second finite TCA consists of 4x2 patches and occupies a λ/3.2 x λ/3.2 aperture on a λ/26 thick substrate (mid-frequency is at 2 GHz). This antenna delivers 17.3% impedance bandwidth, 4.8dB realized gain (95% efficiency) and 30% gain bandwidth. That is, more than twofold impedance bandwidth is delivered as compared to a single patch antenna of the same size on conventional or EBG substrate. The third array being considered consists of 3x2 patches occu (open full item for complete abstract)

Committee: John L. Volakis PhD (Advisor); Kubilay Sertel PhD (Advisor); Robert J. Burkholder PhD (Committee Member); Fernando L. Teixeira PhD (Committee Member) Subjects: Electrical Engineering; Electromagnetics

Master of Science in Electrical Engineering (MSEE), Wright State University, 2023, Electrical Engineering

A method for software-defined radio array calibration is presented. The method implements a matched filter approach to calculate the phase shift between channels. The temporal stability of the system and calibration coefficients are shown through the standard deviation over the course of four weeks. The standard deviation of the phase correction was shown to be less than 2 deg. for most channels in the array and within 8 deg. for the most extreme case. The standard deviation in amplitude scaling was calculated to be less than 0.06 for all channels in the array. The performance of the calibration is evaluated by the antenna gain and the difference from the ideal beam shape for the peak side lobe level and first null depth. For one example data collection, the gain was 61 dB for the array with a maximum difference of 0.2246 dB for the peak side lobe level and 0.3998 dB for the first null depth.

Committee: Michael A. Saville Ph.D. (Advisor); Zhiqiang Wu Ph.D. (Committee Member); Josh Ash Ph.D. (Committee Member) Subjects: Electrical Engineering

Master of Science in Electrical Engineering (MSEE), Wright State University, 2019, Electrical Engineering

This study focuses on the use of microstrip antenna technology for designing an ultra-wideband antenna to meet low size, weight and power requirements. Based on the recent literature for such antennas, a quasi-log periodic microstrip antenna array is designed to operate from 8 to 40 GHz (radar bands X, Ku, K and Ka). The array consists of 33 co-linear, inset-fed, square patches on a Roger's Duroid substrate, and is modeled using the Advanced Design System software from Keysight. The simulated results show the antenna has pass-band gains greater than 5 dB, a half-power beamwidth of 30 degrees, and linear polarization with a broadside radiation pattern. In addition, the fractional voltage standing wave ratio is less than 1.8 for 18 GHz of the pass-band, and the antenna has an efficiency greater than 60 percent over the entire pass band.

Committee: Michael A. Saville Ph.D., P.E. (Advisor); Yan Zhuang Ph.D. (Committee Member); Saiyu Ren Ph.D. (Committee Member); Josh Ash Ph.D. (Committee Member) Subjects: Electrical Engineering; Electromagnetics; Technology

Master of Science in Engineering, University of Akron, 2018, Electrical Engineering

Beamforming is a signal processing technique that is utilized in many communications and signal processing applications. Beamformers help to improve signal quality and enhance the performance of sensor networks and communications arrays. Current digital design methods may require the use of an FPGA or ASIC to perform signal processing. These implementations can be very expensive in terms of design cost and production cost. For this reason, it is worth investigating analog design approaches which can be implemented efficiently and inexpensively using analog design techniques. This thesis explores the recent developments in method and algorithm, and demonstrates applicability to analog beamforming. Two algorithms are investigated and tested: the Delay Vandermonde Matrix (DVM) and a novel analog implementation of the Farrow filter. The DVM design implements a five-beam multi-beam beamformer while the analog Farrow filter implements a single beam which is steerable in the range of 0º to 60º. These two algorithms are analyzed in the analog domain and prototype designs were developed, built, and tested in the laboratory. The prototype designs implemented audio beam-forming using analog electronic components for a four-element array of miniature speaker drivers. A 64-element array of miniature speaker drivers was also analyzed and tested using the same prototype designs. The results from these prototype designs were analyzed and show that a 10dB to 15dB beam intensity can be achieved with the speaker arrays. The results demonstrate that the analog design approach can be a viable and cost effective alternative to typical digital design approaches. This research may have specific applications to teleconference, home theater, virtual reality, and other audio applications.

Committee: Arjuna Madanayake PhD (Advisor); Hamid Bahrami PhD (Committee Member); Kye-Shin Lee PhD (Committee Member) Subjects: Acoustics; Computer Engineering; Electrical Engineering; Engineering

Doctor of Philosophy, The Ohio State University, 2015, Electrical and Computer Engineering

For satellite communications, traditional phased array antennas could offer advantages over reflector antennas such as increased functionality, conformality, and no feed blockage. However, phased array systems are complex and expensive and, thus, not commonly used for satellites. Indeed, many applications (radar, electronic warfare, communications, etc.) would greatly benefit from less expensive phased array systems. Thus, much effort has been invested into addressing these challenges. This dissertation aims to greatly improve the feasibility of traditional phased arrays by eliminating the array backend (the main source of cost and complexity). Specifically, we introduce a traveling wave array (TWA) concept using a single feedline whose propagation constant can be controlled to enable scanning. This is done using a small mechanical movement (<100mil) to adjust the feedline propagation constant. In this manner, the phase delivered to each element can be altered, enabling scanning. Of importance, beam steering is achieved with only one feed and one small mechanical movement (for any size linear array) without using individual phase shifters. Four specific TWA implementations are presented: 1) parallel plate waveguide (PPW) array, 2) trapezoidal wedge coplanar stripline (TWCPS) array, 3) vertical PPW array, and 4) metal PPW array. Each of these three TWAs is comprised of a 20+ element linear array with stable realized gain and low side lobe level (SLL) across -25°≤θ≤25° scanning range. This dissertation describes the design procedure for each TWA, including element, feed, termination, and aperture excitation. Fabrication procedures and challenges are provided. Fabrication for these unique TWA geometries is found to be a key challenge for the concept. Prototype measurements are compared to simulations. The dissertation culminates in the metal PPW array which overcomes many of the challenges encountered by the previous designs. The array achieves st (open full item for complete abstract)

Committee: John Volakis (Advisor); Chi-Chih Chen (Advisor); Christopher Baker (Committee Member) Subjects: Electrical Engineering; Electromagnetics; Engineering

Doctor of Philosophy, The Ohio State University, 2011, Electrical and Computer Engineering

The need for high resolution imaging radars and high data rate telecommunications has direct implications for the employed antennas. Specifically, modern RF front-ends require ultra-wideband (UWB) performance using low profile antennas for inconspicuous installation. Other functionalities such as beam steering and multiple input multiple output (MIMO) are highly desired in an effort to create diverse, multi-functioning antenna systems. To this end, antenna arrays have been successfully used for beam steering and MIMO applications. However, a key limitation is narrow bandwidth and often bulky size (i.e. non-conformal). Also, in the past, arrays were designed to have minimum mutual coupling. This itself limited their bandwidth to that of their individual antenna elements. More recently, a novel class of antennas referred to as “tightly coupled phased array” (TCPAs) were shown to exhibit UWB performance while residing on a thin substrate. In contrast to traditional arrays, TCPAs utilize the mutual capacitance between array elements to counteract the ground plane inductance. Typically, TCPAs provide very large bandwidths (up to 5:1) while maintaining small thickness (λ/10 at the lowest operational frequency). It has been shown that TCPAs are a class of metamaterial antennas, and thus inherently provide significant wave slow-down that can be harnessed for miniaturization. This miniaturization can be exploited for bandwidth increase. Specifically, utilization of the wave slow-down resulted in a novel UWB interwoven spiral array (ISPA) that achieved 10:1 bandwidth using λ/23 thickness. Although the design of tightly coupled arrays is well understood, for a successful implementation several key challenges remain to be addressed. Firstly, finite size arrays suffer from reduced bandwidth due to non-uniform excitation and insufficient mutual coupling. To alleviate this issue, in this dissertation we propose a novel excitation technique based on the characteristic (open full item for complete abstract)

Committee: John Volakis (Advisor); Kubilay Sertel (Advisor); Johnson Joel (Committee Member); Teixeira Fernando (Committee Member); Garbacz Robert (Committee Member) Subjects: Electrical Engineering

Master of Science in Engineering, University of Akron, 2012, Electrical Engineering

A broadband digital beamforming algorithm is proposed for directional filtering of temporally-broadband bandpass space-time (ST) plane-waves (PWs) at radio frequencies (RFs). The enhancement of desired waves, as well as rejection of undesired interfering PWs, is simulated. A massively-parallel synchronous and asynchronous array architecture is proposed for the real-time implementation of 2nd-order two-dimensional (2D) infinite impulse response (IIR) spatially-bandpass (SBP) beam filters having potential applications in broadband beamforming of temporally down-converted RF signals. The higher speed of operation and potentially reduced power consumption of the asynchronous architecture in comparison to the conventional synchronous hardware have emerging applications in radio-astronomy, radar, navigation, space science, cognitive radio and wireless communications. Further, the bit error rate (BER) performance improvement along with the reduced computational complexity of these digital filters over digital phased array feed (PAF) beamformer is provided. A nominal BER versus signal-to-interference ratio (SIR) gain of 2-3 dB at approximately half the number of parallel multipliers compared to digital PAF, is observed. A novel discrete-space continuous-time (DSCT) analog circuit implementation of the 2D IIR SBP beam filter using ideal operational amplifiers is also proposed.

Committee: Arjuna Madanayake Dr. (Advisor); Hamid Bahrami Dr. (Committee Member); S. I. Hariharan Dr. (Committee Member) Subjects: Electrical Engineering

Doctor of Philosophy, The Ohio State University, 2021, Computer Science and Engineering

Increasingly, the ability of human beings to understand the universe and ourselves depends on our ability to obtain and process data. With an explosion of data being generated every day, efficiently storing and querying such data, usually multidimensional and can be represented using an array data model, is increasingly vital. Meanwhile, along with more and more powerful CPUs and accelerators adding into the system, most modern computing systems contain an increasingly complex I/O stack, ranging from traditional disk-based file systems to heterogeneous accelerators with individual memory spaces. Efficiently accessing such a complex I/O stack in array processing is essential to utilize the enormous computational power of modern computational platforms. One key to achieving such efficiency is identifying where the data is being generated or stored, and choosing appropriate representation and processing strategies accordingly. This dissertation focuses on optimizing array processing in such complex I/O stacks by studying these two fundamental questions: what data representation should be used, and where the data should be stored and processed. The two basic scenarios of scientific data analytics are considered one-by-one; The first half of the dissertation tackles the problem of efficiently processing array data post-hoc, presents a compact array storage for disk-based data, integrating lossless value-based indexing into it. Such integrated indices improve the value-based filtering operation performance by orders of magnitude without sacrificing storage size or accuracy. The dissertation then demonstrates how complex queries such as equal and similarity array joins can also be performed on such novel storage. The second half of the dissertation focuses on data generated by simulations on accelerators in-situ without storing the generated data. The system generates an improved bitmap representation on GPU to reduce the bandwidth bottleneck between host and accelerat (open full item for complete abstract)

Committee: Rajiv Ramnath (Advisor); Gagan Agrawal (Advisor); Jason Blevins (Other); Yang Wang (Committee Member); Srinivasan Parthasarathy (Committee Member) Subjects: Computer Engineering; Computer Science

Doctor of Philosophy (Ph.D.), University of Dayton, 2020, Electrical and Computer Engineering

The Frequency Diverse Array (FDA) antenna provides range - angle - time dependent beampattern, potentially generating highly directional beams with high gain that may be steered directly and continuously to the desired position. This research explores using FDA antenna for tracking a Low Earth Orbit (LEO) satellite. Although FDA array antenna has been growing in use for radar communication systems with advantages of it is electronically beam steering, it is still not truly used in integrate with LEO systems. The mathematical model of FDA antennas with dierent geometries for tracking LEO satellite is presented. Then, the radiation characteristics of linear and Planar-FDA under dierent situations are investigated. Further, the planar FDA array owns greater superiority over the linear FDA array, and it can cover the observation space indicating great potential in LEO tracking and communication applications. A ground receiving antenna system based on planar FDA array antenna is presented for tracking and communicating with (LEO) satellite at ground station. This is required to minimize a complexity and the cost of ground station. To meet the system gure of merit (G/T) requirement, the radiation characteristics, the gain requirements, the array size, the minimum number of elements and their distribution for several FDA array antenna architectures are calculated and analyzed. Moreover, a general overview of system temperature is presented including a noise model for FDA array antenna, and the link budget analysis and evaluation are introduced.

Committee: Michael Wicks Phd (Advisor) Subjects: Engineering

Doctor of Philosophy, Case Western Reserve University, 2019, Physics

For over a decade both the Pierre Auger (PA) and Telescope Array (TA) obser- vatories have been monitoring the sky for Ultra High Energy Cosmic Rays, with PA in the Southern Hemisphere and the TA in the Northern. Both observatories use similar architecture in their hybrid detector arrays, but use notably different detector hardware and data analysis methods. The goal of this research is to enable cross cal- ibration of The PA hardware relative to that of the TA's, and to ultimately allow for simultaneous direct detection and reconstruction of identical extensive air showers. The cross calibration of hardware was conducted by deploying and operating both two PA type surface detectors, and a TA type surface detector fitted with special triggering electronics at the TA central lasing facility, and allowing them to collect local cosmic ray triggering data over the course of several months. The parameter utilized to make the cross calibration is the calibrated detection energy of the two different stations, that being MIP for TA and VEM for PA. The new TA electronics were found to function as designed, and were used to find that the PA South Type and the TA type surface detectors experience a systematic time offset of -1.098±0.1995 μsecs. This result was applied to data representing cosmic ray events recorded by both the TA and PA types of detectors and an upper bound to the cross calibration factor of 1.22 ± 0.34, and a lower bound of 0.77 ± 0.20 were found, with this factor representing M IP = C × V EM . As data continues to be recorded these bounds will converge onto a conversion factor that will be utilized to directly compare TA and PA data sets. Direct detection and reconstruction of air showers will be facilitated by the com- pletion of the Micro Array, an array of PA type surface detectors co-location with TA surface detectors at the TA Observatory, that will operate concurrently with the up- graded TA Observatory. Two configurations f (open full item for complete abstract)

Committee: Corbin Covault (Advisor); Kash Kathleen (Committee Member); Ruhl John (Committee Member); McGaugh Stacy (Committee Member) Subjects: Physics

Doctor of Philosophy, Case Western Reserve University, 2019, Physics

In this dissertation, we will describe work completed towards the Pierre Auger Observatory's AugerPrime Upgrade as well as auxiliary timing work, hardware design and finally a test of correlations of Starburst Galaxies with the arrival directions of Ultra High Energy Cosmic Rays (UHECRs). In the first three chapters, we review the history, observables and detection techniques of UHECR physics, both past and present. We then look at the future upgrade of Auger and give an in depth description of the firmware, software and hardware that make up the Upgraded Unified Board (UUB), which is to be at the heart of AugerPrime. A discussion of the scientific mechanisms and merits of event-by-event composition measurements is presented, and the necessity of a new board to support this is exposed. We then move into the precision timing implementation in AugerPrime, discussing GPS receiver selection and time-tagging system performance. We find that the timing resolution of the UUB is σ_det = 8.44 ± .15 ns, and confirm it using two methods. Subsequent to this, we discuss auxiliary timing projects which support Auger as well as the Cherenkov Telescope Array. Results are shown for an experiment to determine spatial correlations of GPS timing errors, and hardware for timing at CTA and in the Auger@TA cross calibration is described. In the final chapter of this work, we move on to examining the recent Starburst correlation result of the Auger Collaboration, and cross check this by invoking a magnetic field model and back-tracing the arrival directions of UHECRs seen by Auger. We test to see how likely it is that the observed UHECR sky is more correlated with the observed Starburst Galaxy (SBG) sky than an isotropically chosen set of random sources. The test shows a deviation from isotropy at the 1.6σ level. Finally, we describe future directions for SBG correlation tests.

Committee: Corbin Covault (Advisor); John Ruhl (Committee Member); Benjamin Monreal (Committee Member); David Kazdan (Committee Member) Subjects: Astrophysics; Electrical Engineering; Particle Physics; Physics

Doctor of Philosophy, The Ohio State University, 2017, Electrical and Computer Engineering

This dissertation deals with novel ways to reconfigure the bandwidth of tightly-coupled arrays (TCAs). TCAs constitute a class of phased antenna arrays that demonstrate ultra-wide bandwidth, high gain, wide scanning, compact size and low fabrication cost. These attributes render them attractive for a wide range of applications, including multiple-input multiple-output (MIMO) systems, synthetic aperture radar (SAR) and software defined radio (SDR). However, TCAs, like all wideband systems, suffer from signal-to-interference-plus-noise ratio (SINR) degradation, reducing channel capacity and quality of communication. Existing spatial and digital filtering techniques fail to provide a comprehensive solution suppressing both noise and interference simultaneously. Therefore, bandwidth reconfiguration techniques, implemented in analog and at the RF frequency, are highly attractive. In this work, a low loss reconfiguration approach, using variable capacitors within a TCAs balun feed structure, is proposed. Specifically, a rejection notch, tunable both in center frequency and bandwidth, is created, rejecting noise and interference within the entire TCA scanning volume. The proposed reconfigurable array exhibits strong advantages over the use of stand-alone band rejection antennas or the alternative use of tunable band rejection filters, placed after the antenna. The proposed scheme is validated experimentally via fabrication and testing of reconfigurable balun prototypes, both in isolation and within an array environment. Digital MEMS capacitors were utilized for the practical implementation of the tunable band rejection. Measurement results demonstrate tunability with >2:1 frequency tuning range and rejection magnitude in excess of 30dB. The scheme can be expanded to multiple rejection notches, providing complete control over the bandwidth. An alternative way of reconfiguring the bandwidth of a TCA is also examined. This method incorporates a reconfigurable fre (open full item for complete abstract)

Committee: John Volakis (Advisor); Robert Burkholder (Committee Member); Asimina Kiourti (Committee Member) Subjects: Electrical Engineering

Master of Environmental Science, Miami University, 2017, Environmental Sciences

The purpose of this research was to determine the best design for a solar array to be located at Miami University to produce all of the University's electricity needs over any given year. Computer simulations were carried out using the NREL PVWATTS online calculator and the NREL System Advisor Model (SAM) which both use the NREL Typical Model Year (TMY) climate data sets. Two primary types of solar arrays were analyzed: fixed position (FP) and single-axis tracking (SAT). Simulations were repeated using varied solar panel tilt angles and array azimuth angles. Hourly expected electricity generation data from simulations was given a dollar value from the hourly rates charged to the University by Duke Energy. Simulations were then compared by hourly total electricity generation and total dollar value to determine the best configurations. Analysis showed that the best configuration for FP solar was a tilt of 31.5° away from horizontal, and an azimuth of 195°S, and a default tilt of 31° and azimuth of 185°S for SAT. The SAT array required 22.1% fewer panels, and 6 more acres. Either array would also save 1,641,813 metric tons of carbon emissions. Financial analysis found a PPA to be the most economically feasible option.

Committee: Scott Johnston RA (Advisor); Sarah Dumyahn Dr. (Committee Member); Mark Scott Dr. (Committee Member) Subjects: Alternative Energy; Business Costs; Energy; Engineering; Environmental Economics; Environmental Engineering; Environmental Science; Environmental Studies; Higher Education Administration; Sustainability

Master of Science, University of Akron, 2017, Electrical Engineering

Radio frequency (RF) antenna array beamforming based on electronically steerable wideband phased-array apertures find applications in communications, radar, imaging and radio astronomy. High-bandwidth requirements for wideband RF applications necessitate hundreds of MHz or GHz frame-rates for the digital array processor. Systolic array architectures are often employed in multi-dimensional (MD) signal processing for linear and rectangular antenna arrays. Thus, this research used a FPGA hardware platform, the ROACH-2, which is equipped with a Xilinx Virtex-6 SX475T FPGA chip, and which is widely used in the field of radio astronomy. The research concentrated on the prospects of implementation of systolic array based MD beamformers on the ROACH-2, and on methods of extending the operating frequency to GHz range by using polyphase structures. The proposed systolic array architectures employ a differential form 2-D IIR frequency planar beam filter structure which is low in hardware utilization. The study highlights techniques that can be used to overcome the limitations of the ROACH-2 signal processing platform to achieve high operating frequencies.

Committee: Arjuna Madanayake (Advisor); Subramaniya Hariharan (Committee Member); Joan Carletta (Committee Member) Subjects: Communication; Electrical Engineering; Engineering

Doctor of Philosophy, The Ohio State University, 2016, Electrical and Computer Engineering

This work advances state-of-the-art Radio Frequency (RF) emitter geolocation from an airborne or spaceborne antenna array. With an antenna array, geolocation is based on Direction of Arrival (DOA) estimation algorithms such as MUSIC. The MUSIC algorithm applies to arbitrary arrays of polarization sensitive antennas and yields high resolution. However, MUSIC fails to obtain its theoretical resolution for simultaneous, closely spaced, co-frequency signals. We propose the novel Nullspace MUSIC algorithm, which outperforms MUSIC and its existing modifications while maintaining MUSIC's fundamental orthogonality test. Nullspace MUSIC applies a divide-and-conquer approach and estimates a single DOA at a time. Additionally, an antenna array on an aircraft cannot be perfectly calibrated. RF waves are blocked, reflected, and scattered in a time-varying fashion by the platform around the antenna array. Consequently, full-wave electromagnetics simulations or demanding measurements of the entire platform cannot eliminate the mismatch between the true, in-situ antenna patterns and the antenna patterns that are available for DOA estimation (the antenna array manifold). Platform-induced manifold mismatch severely degrades MUSIC's resolution and accuracy. We show that Nullspace MUSIC improves DOA accuracy for well separated signals that are incident on an airborne antenna array. Conventionally, geolocation from a mobile platform draws Lines of Bearing (LOB) from the antenna array along the DOAs to find the locations where the DOAs intersect with the ground. However, averaging the LOBs in the global coordinate system yields large errors due to geometric dilution of precision. Since averaging positions fails, a single emitter is typically located by finding the position on the ground that yields the Minimum Apparent Angular Error (MAAE) for the DOA estimates over a flight. We extend the MAAE approach to cluster LOBs from multiple emitters. MAAE clustering geolocates multiple sim (open full item for complete abstract)

Committee: Inder Gupta (Advisor); Joel Johnson (Committee Member); Fernando Teixeira (Committee Member); Can Koksal (Committee Member) Subjects: Aerospace Engineering; Applied Mathematics; Computer Engineering; Computer Science; Electrical Engineering; Electromagnetics; Electromagnetism; Engineering; Experiments; Mathematics; Music; Remote Sensing; Scientific Imaging; Systems Design

Master of Science (M.S.), University of Dayton, 2016, Electrical Engineering

The main objective of this research is to develop an antenna array that can tune its radiation pattern over a fixed frequency of operation. For this purpose, a novel printed antenna array for beam peak shifting applications is presented. This antenna array consists of two bowtie slots separated over a distance of half wavelength. A conductor backed coplanar waveguide (CBCPW) is designed with signal line of one wavelength connected to the bowtie antenna linear array. The bowtie antenna surrounded by CBCPW ground lines acts as a radiating element. The frequency of operation of this array is 9.27 GHz which is reconfigured by the tuning varactors loaded on the signal line of one of the antenna in the array. After varying capacitance of the varactors on the signal line of CBCPW, alters the S parameters of the antenna array. The return loss of the antenna array in the frequency of operation is below -10dB, which suits the requirement of a working antenna. The radiation pattern of the antenna array is tuned as its beam shifts over a range of 10 degrees to 27 degrees.

Committee: Robert Penno Ph.D. (Committee Chair); Guru Subramanyam Ph.D. (Committee Member); Monish Chatterjee Ph.D. (Committee Member) Subjects: Electrical Engineering

PhD, University of Cincinnati, 2009, Engineering : Electrical Engineering

As technology advances, the need for the agile optics is only increasing. Agile optics are essential for such applications as electronic paper, lightweight beam deflection (heads-up displays and laser-radar), light harvesting, free-space laser communication, cell phone cameras, and 3-D holographic displays, to name a few. In state of the art cell phones, the optical elements for the camera are required to be both robust and have variable focus. While Micro-Electro-Mechanical Systems (MEMS) and Liquid Crystal based technologies are already being employed to produce such optical elements, they have been unable to produce the same characteristics found in modern solid optics (i.e. transmission, polarization free and high numerical aperture). A liquid electro-optical device based on electrowetting is an alternate technology that has great promise to replicate the performance of solid geometrical optics. Electrowetting is voltage-induced manipulation of small drops of polar liquids placed on a dielectric surface. This technology is already being employed in cell phone technologies to create robust, variable focus liquid lens systems. Lenses are not the only geometrical shapes, which can be formed using electrowetting. Beam steering elements can also be formed by replicating prism geometry. This thesis is dedicated to early stage pursuit of electrowetting prisms for beam and image steering. Presented in this dissertation is the demonstration of the first electrowetting beam steering devices. Along with the demonstration of the beam steering device, the several factors that need to be considered when working with flat electrowetting optical systems are also explored. This includes an investigation of the fundamental performance limits (speed, voltage, temperature, optical absorption, reliability, fabrication) of an electrowetting beam steering system. Topics included in this dissertation are the 3D fabrication techniques for microlens and microprism arrays in two types of (open full item for complete abstract)

Committee: Jason Heikenfeld PhD (Committee Chair); Stephen Kowel PhD (Committee Member); Joseph Thomas Boyd PhD (Committee Member); Joseph Haus Ph.D. (Committee Member); Andrew Steckl PhD (Committee Member) Subjects: Electrical Engineering

MS, University of Cincinnati, 2003, Engineering : Electrical Engineering

Direction Finding (DF) system is used in many military and civilian operations such as surveillance, reconnaissance, and rescue, etc. In the past years, direction finding system is implemented usually using analog RF techniques such as Butler matrix and analog beamforming. Analog direction finding systems have drawbacks inherent from their analog properties such as expensive implementation, inflexibility to adjust or change functionality, intensive calibration procedures and etc. The digital technique relies on reconfigurable logic implementations. Thus it is more flexible and less expensive compared with its analog counterpart. In a digital direction finding system, all the received signals by array elements are sampled and digitized into digital format. They are processed by a high throughput digital processor. The whole system is much more reliable and accurate. Digital implementation of the direction finding system becomes practically exploitable in recently years. In this research work, we design a high throughput digital direction finding (DDF) system. It implements the digital Butler matrix to accomplish the direction finding task. Through theoretical timing error analysis, we then estimate the performance that the digital direction finding system can achieve. We also analyze how to choose the geometry of the antenna array, array size and so forth, based on theoretical and practical considerations.

Committee: Dr. Howard Fan (Advisor) Subjects: