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Hussain, Mallik Mohd RaihanNonlinear Electromagnetic Radiation from Metal-Insulator-Metal Tunnel Junctions
Master of Science (M.S.), University of Dayton, 2017, Electro-Optics
Our goal was to experimentally detect nonlinear electromagnetic (EM) radiation (in the far field) from a metal-insulator-metal (MIM) tunnel junction where the insulator thickness lies in the nanometer to subnanometer range and the metals in the junction are coupled to the electromagnetic field of incident photons. The radiation from an MIM junction originated from the photon-induced tunneling current passing through it. The phenomenon is elegantly described by photon-assisted-tunneling (PAT) theory that introduces transfer Hamiltonians in the uncoupled (when two metals are at infinite distance from each other) system Hamiltonian. This theory predicts the contribution of additional conductivity terms in the MIM interface (due to tunneling inside the junction) and ushered the development of quantum conductivity theory (QCT), as a consequence. In this thesis, we reviewed QCT from the perspective of many-body formulation and designed careful experiments to detect the nonlinear electromagnetic radiation from MIM junctions that can be attributed to photon-assisted tunneling of electrons. In our experiment, first, an insulator layer was put on the metal surface using atomic layer deposition (ALD) technique. The number of layers were varied to produce MI samples with different insulator thickness in the subnanometer range. Then, we set the background signal strength by measuring the second harmonic (SH) and third harmonic (TH) signal due to the bulk material and the surface of metal-insulator (MI) interface. Next, we spin-coated the MI sample with Au nanospheres (diameter ~ 10 nm) to construct MIM interfaces and measured SH and TH signals from them again. Without any bias voltage across the MIM, QCT predicts an increase in TH signal only. Experimentally, we observed an increase in TH signal strength. The increase was modest which is partially attributed to the fact that we could not reliably produce MIM samples with subnanometer insulator thickness and uniform coverage. We intend to improve the surface coverage and uniformity of the insulator layer, in future, and measure SH and TH from the improved samples. Detection of such radiation would support QCT and validate the extension of transfer Hamiltonian approach from the realm of superconducting tunnel junctions to normal MIM tunnel junctions.

Committee:

Joseph Haus, Ph.D. (Committee Chair); Andrew Sarangan, Ph.D. (Committee Member); Imad Agha, Ph.D. (Committee Member)

Subjects:

Electromagnetics; Nanoscience; Nanotechnology; Optics; Quantum Physics

Keywords:

tunnel junction; metal-insulator-metal; MIM; nonlinear radiation from MIM; transfer Hamiltonian; photon-assisted-tunneling; PAT; quantum conductivity coefficient; QCT; Au-Al2O3-Au; atomic layer deposition on metal; ALD on metal; metal-insulator; MI

Zuboraj, MD RCoupled Transmission Line Based Slow Wave Structures for Traveling Wave Tubes Applications
Doctor of Philosophy, The Ohio State University, 2016, Electrical and Computer Engineering
High power microwave devices especially Traveling Wave Tubes (TWTs) and Backward Wave Oscillators (BWOs) are largely dependent on Slow Wave Structures for efficient beam to RF coupling. In this work, a novel approach of analyzing SWSs is proposed and investigated. Speci cally, a rigorous study of helical geometries is carried out and a novel SWS "Half-Ring-Helix" is designed. This Half-Ring-Helix circuit achieves 27% miniaturization and delivers 10dB more gain than conventional helices. A generalization of the helix structures is also proposed in the form of Coupled Transmission Line (CTL). It is demonstrated that control of coupling among the CTLs leads to new propagation properties. With this in mind, a novel geometry referred to as "Curved Ring-Bar" is introduced. This geometry is shown to deliver 1MW power across a 33% bandwidth. Notably, this is the first demonstration of MW power TWT across large bandwidth. The CTL is further expanded to enable engineered propagation characteristics. This is done by introducing CTLs having non-identical transmission lines and CTLs with as many as four transmission lines in the same slow wave structure circuit. These non-identical CTLs are demonstrated to generate fourth order dispersion curves. Building on the property of CTLs, a `butterfly' slow wave structure is developed and demonstrated to provide degenerate band edge (DBE) mode. This mode are known to provide large eld enhancement that can be exploited to design high power backward wave oscillators.

Committee:

John Volakis, Dr. (Advisor); Niru Nahar, Dr. (Advisor)

Subjects:

Electrical Engineering; Electromagnetics

Keywords:

Traveling Wave Tubes, Coupled Transmission Lines, Slow Waves, Slow Wave Structures, Degenerate Band Edge

Lee, Cedric WA Wireless, Fully-Passive Recorder for Medical Applications
Doctor of Philosophy, The Ohio State University, 2016, Electrical and Computer Engineering
This dissertation presents a fully-passive wireless neurorecording system for moni- toring very low level neuropotential. The subject new recording device has no battery, power harvester or regulator. As a result, it addresses concerns related to: (1) exter- nal wired connection (causing lack of mobility and risk of infection in patients), and (2) heat generation that may impact neural functioning. The developed sensor also exhibits large bandwidth and extremely high sensitivity down to 20 µVpp. Specifi- cally, this minimum detectable voltage is 25 times lower than previous fully-passive wireless neurorecorder. Further, for the first time, it allows detection of signals up to 5000 Hz. As a result, it can detect all neural signals of interest. A key aspect of the proposed sensor’s increased sensitivity is the introduction of an anti-parallel diode pair (APDP) to greatly reduce the second harmonic mixing conversion loss in the implant. Also, a smaller size antenna allows for a less intrusive implant. The implant is excited by an external interrogator possibly integrated within a baseball cap, to power the implanted recorder and reading the neurosignal.

Committee:

John Volakis (Advisor); Asimina Kiourti (Advisor); Waleed Khalil (Committee Member); Andrea Serrani (Committee Member)

Subjects:

Electrical Engineering; Electromagnetics

Keywords:

neurosensing; apdp; subharmonic mixer; fully-passive; wireless; implant; neurosensor

Algadey, TarigInvestigation of Negative Refractive Index in Isotropic Chiral Metamaterials Under First and Second-Order Material Dispersion With and Without Conductive Loss
Doctor of Philosophy (Ph.D.), University of Dayton, 2016, Electrical Engineering
In recent years, considerable research has been carried out relative to the electromagnetic (EM) propagation and refraction characteristics in metamaterials with emphasis on the origins of negative refractive index. Negative refractive index may be introduced in metamaterials via different methods; one such is the condition whereby the Poynting vector of the EM wave is in opposition to the group velocity in the material. Alternatively, negative refractive index also occurs when the group and phase velocities in the medium are in opposition. The latter phenomenon has been investigated extensively in the literature, including recent work involving chiral metamaterials with material dispersion up to the first order. This dissertation examines the possible emergence of negative refractive index in dispersive chiral (lossless and lossy) metamaterials with material dispersion up to the first and second order. The motivation of this work has two parts- the first part is to determine if using second- as opposed to first-order material dispersion may lead to more practically realizable negative index behavior in the lossless material; the second part is to determine if including the conductive loss to the medium with material dispersion up to the first order (a feature likely to be present in most realistic cases; conductive losses in such materials as nanometals, or dielectric losses in a variety of other nanomaterials, such as lithium niobate and Sic+Ag) may lead to the emergence of negative index. This dissertation investigates the above problems (with the exception of lossy dielectrics, the determination of which is currently ongoing) by using spectral and phasor plane-wave based analytical approaches as well as alternative analysis incorporating practical physical models into the electromagnetic equations. In this work, a spectral approach combined with slowly time-varying phasor analysis is applied leading to the derivation of EM phase and group velocities analytically, and the resulting phase and group velocities and the corresponding phase and group indices are evaluated by selecting somewhat arbitrary dispersive parameters. The results indicate the emergence of negative index (via negative phase indices along with positive group indices, as reported in the literature) or NIM behavior over information bandwidths in the low RF range. The second-order results are not significantly better than those for first-order based on the theoretical analysis; however, greater parametric flexibility exists for the secondorder system leading to higher likelihood of achieving NIM over practical frequency bands. The velocities and indices computed using the Lorentzian and Condon models. More importantly, NIM is found not to occur in first-order when using practical models. Also we have revisited the first order calculations and it is seen that (In the lossless -first order calculations) to match up with all negative index conditions or requirements, the relative electric permittivity and relative magnetic permeability must be negative in the NIM region. We investigated that the relative electric permittivity and magnetic permeability just can be negative in the negative sideband frequency. In the lossy case, the loss is introduced via the material’s dispersive conductivity, and its effect in achieving NIM is carefully explored. Emergence of NIM is again established. Interestingly, it is found that the usual circular (RCP and LCP) spatial polarization states for the lossless material morph into right-handed spiral states once loss is introduced. These results derived via dispersive spectral analyses are in overall good agreement with corresponding findings in the literature.

Committee:

Monish Chatterjee (Advisor); Partha Banerjee (Committee Member)

Subjects:

Electrical Engineering; Electromagnetics; Physics

Keywords:

Negative index; phase velocity; phase index; group velocity; group index; negative relative electric permittivity; negative relative magnetic permeability; polarization state; right circular polarization; lossy chiral material

Jackson, Richard AramA Preliminary Study of Pump/Probe Angular Dependence of Zeeman Electromagnetically Induced Transparency
Master of Science, Miami University, 2015, Physics
This thesis outlines my work to determine the dependence of Zeeman Electromagnetically Induced Transparency (EIT) on the relative angle between the pump and probe beams. We report initial measurements of Zeeman EIT and EIA using a simple arrangement in which the Zeeman sublevels are scanned around fixed pump and probe frequencies. We introduce improvements in magnetic field uniformity and measure EIT/EIA feature lineshape vs. pump/probe angle. Next, we outline our progress on performing Zeeman EIT/EIA experiments in the traditional format, i.e. scanning the probe frequency while holding the pump frequency fixed, which is more amenable to theoretical modeling.

Committee:

Samir Bali (Advisor); Perry Rice (Committee Member); James Clemens (Committee Member)

Subjects:

Electromagnetics; Experiments; Optics; Physics; Quantum Physics

Keywords:

Electromagnetically Induced Transparency; Zeeman effect; anglular displacement; vapor cells; warm atoms; quantum optics

Yetisir, ErsinNovel Implementations of Wideband Tightly Coupled Dipole Arrays for Wide-Angle Scanning
Doctor of Philosophy, The Ohio State University, 2015, Electrical and Computer Engineering
Ultra-wideband (UWB) antennas and arrays are essential for high data rate communications and for addressing spectrum congestion. Tightly coupled dipole arrays (TCDAs) are of particular interest due to their low-profile, bandwidth and scanning range. But existing UWB (>3:1 bandwidth) arrays still suffer from limited scanning, particularly at angles beyond 45° from broadside. Almost all previous wideband TCDAs have employed dielectric layers above the antenna aperture to improve scanning while maintaining impedance bandwidth. But even so, these UWB arrays have been limited to no more than 60° away from broadside. In this work, we propose to replace the dielectric superstrate with frequency selective surfaces (FSS). In effect, the FSS is used to create an effective dielectric layer placed over the antenna array. FSS also enables anisotropic responses and more design freedom than conventional isotropic dielectric substrates. Another important aspect of the FSS is its ease of fabrication and low weight, both critical for mobile platforms (e.g. unmanned air vehicles), especially at lower microwave frequencies. Specifically, it can be fabricated using standard printed circuit technology and integrated on a single board with active radiating elements and feed lines. In addition to the FSS superstrate, a modified version of the stripline-based folded Marchand balun is presented. As usual the balun serves to match the 50-Ohm coaxial cable to the high input impedance (~200-Ohm) at the terminals of array elements. Doing so, earlier Wilkinson power dividers, which degrade efficiency during E-plane scanning, are eliminated. To verify the proposed array concept, 12x12 TCDA prototype was fabricated using the modified balun and the new FSS superstrate layer. The design and experimental data showed an impedance bandwidth of 6.1:1 with VSWR<3.2. The latter VSWR was achieved even when scanning down to ±60° in the H-plane, ±70° in the D-plane and ±75° in the E-plane. All array components, including the FSS, radiating dipoles and the feed lines are placed on the same PCB, vertically oriented over the array ground plane, resulting in a low-cost and light-weight structure. The effects of finite aperture sizes in presence of FSS or dielectric superstrates are also considered. Specifically, we compare the performance of finite TCDAs with FSS or dielectric loading. The performance metric is beam pointing accuracy for moderate array sizes (~30dBi gain) with various edge element terminations. It is shown that even terminating two unit cells at the array edges can provide effective suppression of edge-born waves and achieve excellent beam accuracy. This is the case when both the FSS elements and radiating dipoles are resistively loaded in the unit-cells along the aperture edges.

Committee:

John L. Volakis, Prof (Advisor); Nima Ghalichechian, Dr (Committee Member); Chi-Chih Chen, Dr (Committee Member); Fernando L. Teixeira, Prof (Committee Member)

Subjects:

Electrical Engineering; Electromagnetics

Keywords:

Wide-angle scanning, wideband antenna, phased array antenna

Vo, Henry HoangDEVELOPMENT OF AN ULTRA-WIDEBAND LOW-PROFILE WIDE SCAN ANGLE PHASED ARRAY ANTENNA
Doctor of Philosophy, The Ohio State University, 2015, Electrical and Computer Engineering
Coupling in phased arrays is a major issue. Mutual coupling causes both gain and bandwidth reduction. Such coupling arises from the presence of adjacent elements that produce scattering and losses during low-angle beam steering. The scattering effect is comprised of (1) structural scattering and (2) antenna-mode coupling and associated losses. Losses occur when the coupled energy received by adjacent elements is dissipated at the back-end loads, resulting in lower gain at wide scan angles. In addition, the interference from periodic nature of large arrays or feed networks may produce undesired scattering modes and traveling waves that limit the upper bound of the operational frequency and maximum scan angle in ultra-wideband (UWB) arrays. As a result, current ultra wideband (UWB) array designs typically have limited scanning to no more than 45° from normal. In this dissertation, we examine the low angle scanning issues. These issues are verified via full-wave simulation. Our studies show that mutual coupling in the H-plane is stronger than in the E-plane, likely due to the dipole element pattern shape. Another focus of this dissertation is the development of an UWB dual-polarization and low angle beam steering array based on the concept of tightly coupled dipole arrays. For this array, we suppress/minimize mutual coupling by redesigning the antenna element, feed geometry, and array structure. Some key design parameters include (1) the simple feed of tightly-coupled dipoles, (2) array height above ground plane, (3) dielectric superstrate, and (4) parasitic coupling ring. The common mode issue is avoided by retaining the ground plane height to less than λmid/4 and the array unit cell size to 0.45λhigh. The final design is also fabricatable on a low-cost PCB. The PCB uses (1) 0.35 mils thick copper corresponding to a standard ¼ oz. copper lamination, (2) 2 mils coupling slot width and plated-thru vias manufacturable using standard PCB process, and (3) standard Roger RT/Ruroid 5880LZ substrate with dielectric constant of 1.96 and Roger RT/Duroid 5880 superstrate with dielectric constant of 2.2. An 18x18 prototype array is fabricated and measured to verify the final design. The total array height of the fabricated prototype is 0.122λ at the lowest operating frequency. It is also demonstrated that the fabricated array is capable of scanning down to more than 60° in the E- and H-planes with impedance bandwidth of 2.62:1 subject to VSWR = 2. Good agreement was also observed between simulations and measurements.

Committee:

Chi-Chih Chen (Advisor); John Volakis (Committee Member); Joel Johnson (Committee Member)

Subjects:

Electrical Engineering; Electromagnetics

Keywords:

phased array antenna; low profile; ultrawideband; wide scan angle

Wei, JiangongSurface Integral Equation Methods for Multi-Scale and Wideband Problems
Doctor of Philosophy, The Ohio State University, 2014, Electrical and Computer Engineering
This dissertation presents approaches to solve the multi-scale and wideband problems using surface integral equation methods based on the skeletonalization technique, which in essence identifies the numerically independent elements from a larger set of unknowns. In the low frequency or multi-scale scenario, overly dense mesh is generated in a global or local scale. The method is extended to composite material through the integral equation discontinuous Galerkkin method via enhanced enforcement of transmission conditions. Conventional multi-level fast multipole method(MLFMM) faces low frequency breakdown since a large number of basis functions are concentrated within the leaf level groups, whose size is typically larger than λ/4. The computational complexity rapidly approaches that of conventional MoM, which is O (N 2) for both CPU time and memory consumption for iterative solvers. In this dissertation a hierarchical multi-level fast multipole method (H-MLFMM) is proposed to accelerate the matrix-vector multiplication for low frequency and multi-scale problems. Two different types of basis functions are proposed to address these two different natures of physics corresponding to the electrical size of the elements. Moreover, the proposed H-MLFMM unifies the procedures to account for the couplings using these two distinct types of basis functions. O(N) complexity is observed for both memory and CPU time from a set of numerical examples with fixed mesh sizes. Numerical results are included to demonstrate that H-MLFMM is error controllable and robust for a wide range of applications. On the other hand, condition number of the system matrix deteriorates due to the overly dense mesh. This would greatly affect the convergence of iterative solvers, if convergence can ever be attained. Direct solver This thesis proposes an algorithm exploits the smoothness of the far field and computes a low rank decomposition of the off-diagonal coupling blocks of the matrices through a set of skeletonalization processes. Moreover, an artificial surface (the Huygens' surface) is introduced for each clustering group to efficiently account for the couplings between well-separated groups. Furthermore, a recursive multi-level version of the algorithm is developed subsequently. Through numerical examples, we found that the proposed multi-level direct solver can scale as good as O(N 1.3) in memory consumption and O(N 1.8) in CPU time, for moderate-sized EM problems as the electrical size grows. An novel IEDG method with enhanced enforcement of transmission conditions is proposed based on the IEDG algorithm scheme, this makes it possible to solve surface integral equation without being confined to conformal mesh and basis functions with inter-element continuity. Basis functions with different definitions and polynomial orders can be mixed flexibly to form a robust surface integral equation solver for multi-scale structures. IEDG algorithm allows local mesh refinement and greatly facilitates wideband analysis. This algorithm is then enhanced by improved enforcement of the transmission conditions, particularly for highly resonant structures. Finally, infinite ground plane effect is integrated into the algorithm for some more practical problems. Numerical results demonstrated the robustness of the algorithm.

Committee:

Jin-Fa Lee (Advisor); Robert Lee (Committee Member); Fernando Teixeira (Committee Member)

Subjects:

Electromagnetics

Keywords:

Surface Integral Equation, Skeleton Basis Function, Hierarchical Multi-level Fast Multipole Method, Integral Equation Discontinuous Galerkin Method, Transmission Conditions

Smith, Nathanael JNovel Closed-Loop Matching Network Topology for Reconfigurable Antenna Applications
Doctor of Philosophy, The Ohio State University, 2014, Electrical and Computer Engineering
As technology progresses, mobile devices such as laptops, tablets, cell phones, and two-way radios have become smaller in size. Consequently antennas become electrically small to fit inside aggressive packaging requirements with rapidly changing real and imaginary impedances. As such, these antennas are very narrow in bandwidth with high-Q and input impedance which is very sensitive to environmental effects. The radiation efficiency of the device is drastically decreased as the antenna is detuned and signal quality is degraded. As the number of mobile devices we use increases, adaptive impedance tuners have and will become a bigger necessity, especially as more radios are integrated into a single device. This dissertation presents novel improvements to closed loop tuning topologies from a system level perspective addressing impedance tuners, sensing techniques, and how they apply to different antennas. The biggest design hindrance to impedance tuners are losses due to small signal resistance, and loss due to circuit resonances and radiation. A detailed explanation of these loss mechanisms is developed, providing designers with the knowledge to minimize the impact of said losses and improve system efficiency. By exploiting loss mechanisms, a novel small and low cost VHF impedance synthesizer is presented to characterize impedance tuners in load pull measurements. With full consideration of circuit loss mechanisms, a new directional coupler based tuning topology is presented. Traditional tuning topologies aim to minimize |S11| of the matching network. As demonstrated in this work, such a method has the potential to maximize losses in the circuit, especially in multi-stage tuners. Alternative directional coupler based topologies are presented which maximize the system transducer gain. Furthermore, a novel method of sensing a tuned state through the use of a near field probe that detects far field radiated power is introduced. A design guide is detailed with several examples for use with different types of antennas. Concepts developed in this dissertation are demonstrated in an adaptive tuning system where mechanical means of tuning is applied as a low loss tuner. An electrically small monopole is tuned using the power sensor to provide feedback over a 2.2:1 bandwidth (180 to 400MHz) where at the lowest tunable frequency the antenna is 1/11.3 wavelengths in size.

Committee:

John Volakis, Professor (Advisor); Chi-Chih Chen, Professor (Committee Member); Chris Baker, Professor (Committee Chair)

Subjects:

Electrical Engineering; Electromagnetics; Electromagnetism

Keywords:

adaptive impedance tuning; tunable circuits and devices; Automatic tuning topology; impedance matching; load impedance tuner; impedance synthesizer; near-field probe; far-field power sensor; closed-loop tuning; antenna feed-back; small antennas

Wang, ShiyiEngineering Electromagnetic Wave Properties Using Subwavelength Antennas Structures
Doctor of Philosophy (Ph.D.), University of Dayton, 2015, Electro-Optics
With extraordinary properties, generation of complex electromagnetic field based on novel subwavelength antennas structures has attracted great attentions in many areas of modern nano science and technology, such as compact RF sensors, micro-wave receivers and nano-antenna-based optical/IR devices. This dissertation is mainly composed of two parts. For the first part, the idea of plasmonic localization in optical range is transferred and utilized for generating confined fields with high enhancement in RF range. A subwavelength modified bowtie antenna in RF range is designed for generating strong broadband field enhancement in its extended feed gap. The strongly enhanced RF field within the gap can be applied to directly modulate guided optical wave propagating in a waveguide, which enables to realize indirect RF signal sensing through photonic methods. Systematic exploration for modified bowtie antennas and its substrate effect has been given in this part. In the second part, the RF antenna design idea is extended to infrared and optical range based on antenna scaling theory specific for this spectrum. Both transmission and reflection types of metasurface structures have been designed and proposed to obtain optical needle field with a flat-top longitudinal intensity of depth of focus 5λ. With fine adjustment of different nano-antenna structures, both of the metasurfaces enable to generate complex vectorial field with spatial radial polarization, whose amplitude modulation range covers 0.07 to 1 with binary phase control. Then the scattered field can be tightly focused by a high numerical aperture (NA) lens in order to generate longitudinally polarized flat-top field along propagation direction. By exploring the subwavelength antennas’ mechanism and connections between different frequency regions, this dissertation is expected to provide general guidance for design and characterization of next-generation subwavelength antennas structures with extraordinary electromagnetic wave properties.

Committee:

Qiwen Zhan, PhD (Committee Chair); Partha Banerjee, PhD (Committee Member); Andrew Sarangan, PhD (Committee Member); Imad Agha, PhD (Committee Member)

Subjects:

Electromagnetics; Engineering; Experiments; Nanoscience; Nanotechnology; Optics

Keywords:

Subwavelength antennas; vectorial light; meta-surface; nano structures; full wave control; optical needle field

Chen, LiHybrid Silicon and Lithium Niobate Integrated Photonics
Doctor of Philosophy, The Ohio State University, 2015, Electrical and Computer Engineering
A hybrid silicon and lithium noibate (LiNbO3) material system is developed to combine the high index contrast of silicon and the second order susceptibility of lithium niobate. Ion-sliced single crystalline LiNbO3 thin film is bonded to silicon-on-insulator (SOI) waveguides via Benzocyclobutene (BCB) as the top cladding. The LiNbO3 thin films are patterned to achieve desired size, shape and crystal orientations. Integrated electrodes are integrated to confine electric fields to the LiNbO3 thin film. Empowered by the linear electro-optic effect of LiNbO3, compact chip-scale hybrid Si/LiNbO3 integrated photonic devices are enabled on the SOI platform, including radio-frequency electric field sensors, tunable optical filters, high speed electro-optical modulators for optical interconnects, and high linearity modulators for analog optical links. Compact and metal-free electric field sensors based on indirect bonding of z-cut ion-sliced LiNbO3 thin film to silicon microrings are demonstrated. The demonstrated sensitivity to electric fields is 4.5 V m-1Hz-1/2 at 1.86 GHz. Tunable optical filters based on hybrid Si/LiNbO3 microring resonators with integrated electrodes are also demonstrated with a tunability of 12.5 pm/V, which is over an order of magnitude greater than electrode-free designs. By integrating metal thin film electrode and utilizing silicon as an optically transparent electrode, voltage induced electric fields in the LiNbO3 are enhanced. We also presented low power compensation of thermal drift of resonance wavelengths in hybrid Si/LiNbO3 ring resonators. A capacitive geometry and low thermal sensitivity result in the compensation of 17 oC of temperature variation using tuning powers at sub-nanowatt levels. The method establishes a route for stabilizing high quality factor resonators in chip-scale integrated photonics subject to temperature variations. Gigahertz speed hybrid Si/LiNbO3 electro-optical microring modulators are enabled by optimizing the RC time constant of the biasing electrodes. Fabricated devices exhibit a resonance tuning of 3.3 pm/V and a small-signal electrical-to-optical 3 dB bandwidth of 5 GHz. Digital modulation with an extinction ratio greater than 3 dB is demonstrated up to 9 Gb/s. High-speed and low tuning power chip-scale modulators that exploit the high-index contrast of silicon with the second order susceptibility of lithium niobate are envisioned. An alternative design with x-cut LiNbO3 thin films on silicon racetrack resoantors enables compact highly linear integrated optical modulator for high spectral free dynamic range (SFDR) analog optical links. The measured third order intermodulation distortion SFDR is 98.1 dB·Hz2/3 at 1 GHz and 87.6 dB·Hz2/3 at 10 GHz. The demonstrated SFDR is over an order of magnitude greater than silicon ring modulators based on the plasma dispersion effect, and is comparable to commercial LiNbO3 Mach-Zehnder interferometer modulators, but with a footprint three orders of magnitude smaller. The hybrid Si/LiNbO3 photonic platform is promising for applications in optical interconnections, microwave photonics, optical computing and sensing. More broadly, empowering silicon with second-order susceptibility opens a suite of nonlinear optic applications to the chip scale.

Committee:

Ronald Reano (Advisor); Joel Johnson (Committee Member); Fernando Teixeira (Committee Member); Gregory Lafyatis (Committee Member)

Subjects:

Electrical Engineering; Electromagnetics; Nanotechnology; Optics

Keywords:

silicon photonics; integrated optics devices; electro-optical devices; sensors; waveguides; resonators; optical modulators; optical interconnects; microwave photonics; hybrid photonics; integrated optics materials; lithium niobate; micro-fabrication;

Shaver, Ryan J.Analysis of the Tapered Transition Waveguide
Master of Science in Engineering (MSEgr), Wright State University, 2015, Electrical Engineering
The tapered transition waveguide is used in waveguide measurement systems for characterizing biaxial electromagnetic properties of materials, but its complex geometry does not support an analytic field solution. To ensure single-mode field behavior, the system includes sections of standard waveguides that only support the dominant mode. As a result, full-wave modeling and simulation of the system is exceedingly large. Using the finite-element method to analyze the high-order modes at the junctions and to explore field configurations within the transition altering geometry, it is shown that besides the TE10 mode, the TE11 mode is significant. Then, two methods are proposed for using multi-mode excitation in the model as a way to simulate the scattering parameters of a material without the feed and transition section.

Committee:

Michael Saville, Ph.D., P.E. (Advisor); Brian Rigling, Ph.D. (Committee Member); Yan Zhuang, Ph.D. (Committee Member)

Subjects:

Electrical Engineering; Electromagnetics

Keywords:

waveguide; mode matching; T-matrix; transition matrix; scattering parameters

Mahaffey, Joshua VincentA Direct Approach at Field Computation Using the FMM Framework
Master of Science, The Ohio State University, 2012, Electrical and Computer Engineering
For many CEM applications, there is a general need for a fast and direct computation of fields from a known, or approximated, set of sources. The framework of fast multipole methods (FMMs) had been introduced as an efficient means for such computations. However, because of the abundant number of publications which present the FMM in the context of surface integral equation solvers, it is often viewed as applicaple only to boundary integral equation methods in CEM. In this thesis, an attempt is made to return to the roots of the FMM as a way of computing a set of fields directly from known or approximated source current representations. In addition to the difficulties associated with the FMM setup, one of the major issues with a direct computation of fields is in regards to treating the singularities which result from a direct application of the integral operators. As a result, a hypersingularity treatment is also introduced in this thesis for dealing with the direct computation of near-field interactions. In order to demonstrate the very practical reasons for developing a code capable of such direct computation of fields, its efficacy in the recently introduced MS-DDM is studied.

Committee:

Jin-Fa Lee, PhD (Advisor); Robert Burkholder, PhD (Committee Member)

Subjects:

Electromagnetics

Ammanambakkam Nagarajan, DhivyaDesign of HF Forward Transformer Including Harmonic Eddy Current Losses
Master of Science in Engineering (MSEgr), Wright State University, 2010, Electrical Engineering

Pulse Width Modulated (PWM) Forward DC-DC converter is a buck-derived isolated power converter which is used extensively in low power to medium power applications. Satisfactory operation of the transformer utilized in forward converter plays a crucial role in the overall operation of the forward converter. Hence detailed analysis pertaining to design of forward transformer is important. The forward transformer is unique as the magnetizing inductance is not required to store magnetic energy. Additionally, the forward transformer has a tertiary winding, which is required to reset the core and to prevent core saturation. This adds to the complexity of design and analysis as compared to a flyback transformer. The effect of winding losses due to High-Frequency (HF) eddy currents caused by harmonics is also considered in this work. Dowell's equation was extended to determine the winding resistances for forward transformer in Continuous Conduction Mode (CCM). The Fourier series of the transformer winding current waveforms are derived. The winding resistances derived based on the Dowell's expression and the current expressions derived based on spectral analysis are employed in evaluating the winding losses. The procedure to design a HF forward transformer in CCM is presented. The effect of harmonics was computed using MATLAB, and verified by circuit simulation with Saber Sketch. The results were found to be in good agreement.

Committee:

Marian K. Kazimierczuk, PhD (Advisor); Ronald G. Riechers, PhD (Committee Member); Saiyu Ren, PhD (Committee Member)

Subjects:

Electrical Engineering; Electromagnetics; Engineering

Keywords:

Forward transformer; Forward converter; Harmonic Losses; Eddy current Losses; high frequency forward transformer design; winding losses

Hendricks, Jessica MarieELECTROMAGNETIC CHARACTERIZATION OF AF455 WITH DNA-CTMA IN SOLVENT BLENDS
Master of Science (MS), Wright State University, 2013, Physics
This work studies the electromagnetic properties of AF455, a two photon dye, DNA bound with cetyltrimethyl ammonium (CTMA), in liquid solvent blends for use in thin film optical filters. The liquid properties of the materials are believed to be transferred to the films. The solvent blends used are ratios of toluene (T) and dimethyl sulfoxide (DMSO). The complex permittivity and permeability of the samples are measured using the short open coaxial line technique in the frequency range of 1.0 x 107 Hz to 2.0 x 109 Hz. In this frequency range, AF455 does not act as a two photon absorber. The results show there is an interaction between AF455 and DNA-CTMA that increases the real permittivity for two solvent blends (50-50, and 60-40, T-DMSO). There is also a clear conformation change in the samples with the solvents and DNA-CTMA only that is observed in the real permittivity. In the 70-30 blend, the conformation of the DNA-CTMA is a clear helix. In the samples with less toluene the conformation of the DNA-CTMA is a coil structure. The imaginary permittivity increases with the addition DNA-CTMA. The real and imaginary permeability are constant across all samples.

Committee:

Gregory Kozlowski, Ph.D. (Advisor); Angela Campbell, Ph.D. (Committee Member); David Stewart, Ph.D. (Committee Member); Douglas Petkie, Ph.D. (Committee Member)

Subjects:

Electromagnetics; Electromagnetism

Keywords:

AF455, toluene, dimethyl sulfoxide, DNA, CTMA, optical properties, relative permittivity, relative permeability, two photon dye

Patterson, Mark AlanA Passive Wireless Platform for Chemical-Biological Sensors
Doctor of Philosophy (Ph.D.), University of Dayton, 2012, Electrical Engineering
This research presents several different platforms for detecting chemical or biological agents without the use of probes or wires and without the use of a battery. These platforms all use an interrogator to transmit power through either radio or low frequency electromagnetic waves to a sensor device. The sensor device has a functionalized surface which aids in selectivity to the analyte of interest. The sensor device sends back a portion of the power through radio frequency waves with altered frequency, amplitude and phase. The characteristics of the received signal contain the information about the analyte of interest. The platforms were tested with several volatile organic compounds, gasoline, sulfuric acid, hydraulic fluid, and chlorine. The results were statistically significant.

Committee:

Guru Subramanyam, Ph.D (Committee Chair); Partha Banerjee, Ph.D (Committee Member); Malcolm Daniels, Ph.D (Committee Member); James Grote, Ph.D (Committee Member)

Subjects:

Biomedical Engineering; Electrical Engineering; Electromagnetics

Keywords:

chemical sensor; wireless power transfer

O’Donnell, Andrew NickersonOn the Electromagnetic Scattering from Small Grooves in a Conical Surface
Master of Science, The Ohio State University, 2011, Electrical and Computer Engineering
Rapid generation of radar signatures is of particular interest for the missile defense community. These radar signautres are normally found through predictive methods. The two classes of predictive methods are Full-Wave Numerical Solutions and High-Frequency Asymptotic Solutions. Full-Wave Numerical Solutions solve problems in a numerically exact fashion, but are inefficient for electrically large targets. High-Frequency solutions work quickly but rely on the assumption that the target is made up of simple canonical shapes, which is not often the case. Real world objects contain many small features that greatly contribute to the radar signature. One such small feature is a groove on a cone. In this thesis, the scattered fields of a groove around a conical surface is derived. In the high frequency case, the scattering from the groove will reduce to an analytic solution of one or two point scatterers, using the method of stationary phase.

Committee:

Robert Burkholder, PhD (Advisor); Prabhakar Pathak, PhD (Committee Member)

Subjects:

Applied Mathematics; Electrical Engineering; Electromagnetics; Electromagnetism

Keywords:

Electromagnetics; High Frequency Asymptotics; Point Scattering Models; Stationary Phase Approximation

Svendsen, Andrew S. C.GPS Antenna and Receiver for Small Cylindrical Platforms
Doctor of Philosophy, The Ohio State University, 2012, Electrical and Computer Engineering
In the past few decades, GPS has revolutionized navigation positioning and timing with numerous civilian and military applications. Recently, there is increased interest in GPS navigation for small cylindrical platforms which can have a potentially high rotation rate (up to 350 Hz). The purpose of this work is to extend the state-of-the-art of GPS receiver and antenna technology for this specific application of small cylindrical platforms. This presents a set of design challenges for engineers, and this work will make contributions to three aspects of the problem: antenna design, satellite coverage, and receiver design. First, a novel dual-band antenna that provides right-hand circular polarization (RHCP) coverage at the GPS L1/L2 bands for reception of C/A-, P(Y)-, and M-coded GPS signals is designed. The availability of GPS measurements at two bands allows one to remove the biases due to the ionsphere and reception of P(Y) and M-coded signals improves navigation accuracy. Importantly, the antenna size is only 4cm × 4cm × 5.08mm (λ/6 × λ/6 × λ/50). Second, this antenna is specifically designed to have a robust tuning such that it can be mounted on metal cylinders of various diameters (60-160mm) and still function properly. For these cylinders, the antenna has broad RHCP coverage and good gain bandwidth performance. Third, the satellite coverage provided by the antenna is investigated. As expected, a single element cannot provide the full spherical coverage which is needed for continuous satellite tracking as the platform rotates. It is shown that the maximum gain method (i.e. choosing the element with the highest gain) is able to obtain full spherical coverage even with only two elements. However, it is a challenge to implement this method because the time-varying platform attitude is unknown. Therefore, a novel receiver tracking algorithm that implements the maximum gain method is designed by modifying the receiver itself, specifically the delay lock loop. Example results shown that the proposed approach is able to provide continuous satellite tracking as the platform rotates, minimize the number of elements, and eliminate the need for knowledge of the platform attitude.

Committee:

Inder Gupta, PhD (Advisor); Chi-Chih Chen, PhD (Committee Member); Joel Johnson, PhD (Committee Member); Hesham El-Gamal, PhD (Committee Member)

Subjects:

Electrical Engineering; Electromagnetics

Keywords:

GPS antenna; GPS receiver; Antenna for small platforms; Dual-band antenna; GPS multi-channel receiver

Browne, Kenneth EdwardHigh Resolution RADAR Imaging via a Portable Through-Wall MIMO System Employing a Low-Profile UWB Array
Doctor of Philosophy, The Ohio State University, 2011, Electrical and Computer Engineering

There is great desire to employ radio waves to sense objects visually obstructed behind walls or other non-metallic objects. Through-wall imaging (TWI) has a variety of potential applications including avalanche/earthquake rescue, mine detection, and reconnaissance, among others. Synthetic aperture radar (SAR) imaging approaches are typically implemented for TWI due to their inherent high cross-range resolution. However, the generation of SAR images requires movement of the array aperture along a prescribed path. This requirement introduces challenges, as each discrete SAR interrogation location along the path must be precisely known to within the phase resolution of the system in order to maintain coherency (i.e. create a focused image). This is extremely difficult for SAR platforms based upon ground or airborne vehicles, especially in hostile environments. Further, backscatter collection via SAR is inevitably slow (especially when compared to collection speeds of real apertures), and therefore cannot be utilized within applications which are time sensitive.

This dissertation introduces a portable UWB “snapshot” radar sensing system as an alternative to SAR. This system avoids SAR deficiencies by not requiring aperture movement along a path when collecting backscatter from multiple locations. Instead, a single finite planar antenna aperture employing time division multiple-input multiple-output (MIMO) processing is utilized. Ultimately, this allows high resolution image creation quickly and accurately. The subject array measures 55 x 46 cm in aperture, is light-weight (and therefore portable), and exhibits a large 0.9 to 2.3 GHz 3 dB bandwidth. Most importantly, it maintains an extremely low-profile while mounted over a ground plane. The UWB attribute is augmented via the introduction of virtual phase centers interwoven within actual array phase centers. The virtual phase centers provide an artificial increase in array element density and are realized through a unique MIMO array excitation process.

This dissertation focuses on the system design and implementation, followed by quick and efficient formulation of high resolution (specifically along the cross-range dimension) images. The general radar imaging problem, along with a variety of scattering models, is also discussed. Various linear imaging methods are considered along with an efficacious concept, known as coherence factor (CF) weighting, which dramatically enhances the target to clutter ratio (TCR) within an image. High resolution images are then forged via image fusion. That is, an image with enhanced clarity is generated by properly overlaying individual snapshot images from various angularly diversified scene aspects. In addition, several resource (i.e. processing time and computational memory) intense imaging methods are considered which enhance the inherently poor cross-range resolution associated with an image forged from a single snapshot interrogation location. These methods promote sparsity or region homogeneity via a one-norm minimization process.

Finally, a variety of images based upon simulated (via a high frequency scattering code) and experimental (via the proposed snapshot imaging radar) backscatter are presented to demonstrate the efficacy of these approaches. More precisely, several free-space and through-wall (cinderblock) scenes are utilized which encompass complex scattering environments containing metal spheres, trihedrals, plates, cylinders, and a variety of extraneous scatterers.

Committee:

Robert Burkholder, PhD (Advisor); John Volakis, PhD (Advisor); Lee Potter, PhD (Committee Member)

Subjects:

Electrical Engineering; Electromagnetics

Keywords:

radar imaging; antenna arrays; MIMO; array signal processing; beam steering; image optimization; through-wall imaging; image fusion; coherence factor

Evers, ChrisNovel Techniques for Enhancing SAR Imaging using Spatially Variant Apodization
Master of Science, The Ohio State University, 2011, Electrical and Computer Engineering
Conventional radar imaging techniques have long been plagued by problematic sidelobes and poor resolution. Indeed, numerous algorithms exist for combating these two issues. In tackling the first problem the technique spatially variant apodization (SVA) has been utilized for quite some time with tremendously positive results. A more recent enhancement to this technique known as Super-SVA has potential for tackling the second problem. In this thesis, a method is developed for utilizing Super-SVA to enhance down-range and cross-range resolution while minimizing sidelobes without distorting scatterer mainlobes.

Committee:

Robert Burkholder (Committee Member); Eric Walton (Committee Member)

Subjects:

Electrical Engineering; Electromagnetics; Electromagnetism; Engineering

Keywords:

Radar Imaging

Poole, Charles RandallQUENCH PROTECTION STUDIES OF MAGNESIUM DIBORIDE SUPERCONDUCTING MAGNETS FOR MRI APPLICATIONS
Doctor of Philosophy, Case Western Reserve University, 2018, Physics
The use of magnesium diboride (MgB2) superconducting wires inside a conduction cooled MRI main magnet could reduce the amount of liquid helium (LHe) from 2000 to only a few liters. The quench protection of MgB2 superconducting magnets remains a primary challenge because the higher enthalpy margin and slower normal zone propagation velocity (NZPV) of MgB2 wire compared to conventional niobium titanium (NbTi) wire leads to a higher temperature rise, which could damage the magnet, necessitating the use of an active protection system. Both 0.5 T and 1.5 T whole-body conduction cooled MRI main magnet designs with MgB2 wire have been presented here with dimensions comparable to current scanners. The quench propagation throughout the magnet has been numerically modelled using custom code in MATLAB, and the procedure consists of the interaction between thermal, magnetic, and circuit models. The governing heat equations were solved using the implicit Douglas-Gunn and Peaceman-Rachford methods, and the governing circuit equations were solved using Heun’s method. From these simulations, it was found that the temperature rise inside a quenched MRI coil could be reduced at the time of quench detection by increasing the thermal and/or electrical conductivity of the wire composite. A quench protection system using Coupling Loss Induced Quench (CLIQ) has been investigated for the two magnet designs where an external charged capacitor introduces an oscillating current into the coils, which generates heat inside the coils due to inter-filament coupling currents. The coil’s increased resistance reduces the current, leading to a lower hot-spot temperature. Various parameters were varied including the wire’s twist, number of CLIQ units, and the voltage and capacitance of each unit to determine their effect on the magnet’s protection. Finally, these quench simulations were performed on a single MgB2 test coil to determine the quench propagation inside the coil and the effect of a dump resistor and/or external protection heater on the protection of the coil. Therefore, this work has numerically investigated the quench propagation of MgB2 MRI coils and demonstrated both ways to reduce the hot-spot temperature and a potential method of quench protection.

Committee:

Michael Martens (Committee Chair); Robert Brown (Committee Member); Harsh Mathur (Committee Member); Soumyajit Mandal (Committee Member)

Subjects:

Electromagnetics; Physics

Keywords:

Magnetic Resonance Imaging; MRI; Magnesium Diboride; MgB2; High Temperature Superconductor; Quench Protection; Multiphysics Modelling; Numeric Simulation; Superconducting Magnet; Computational Physics;

Esfahani, PedramA Study of the Frequency Dependence of Permittivity and Permeability in Lossless One-Dimensional Composite Right/Left Handed Metamaterials by the Equivalent Circuit Model
Master of Science, University of Akron, 2016, Physics
A medium with a negative permittivity and permeability was first proposed in the 1960s; developments of such a medium did not occur until the late 1990s. Different and new electromagnetic metamaterials have been suggested since 2000. Due to the unusual properties of metamaterials, as a bridge between theory and experiment, computer simulation methods are essential for researchers. The frequency dependence of the permittivity and permeability in an electromagnetic metamaterial constructed of arrays of long thin wires (TWs) and split-ring resonators (SRRs) is presented to demonstrate the effects of macroscopic properties on the electromagnetic properties of the medium. Also, the response of three different materials (Aluminum, Copper, and Silver) is presented to show how material properties of components affect the permittivity and its frequency domain where permittivity and permeability are negative. Based on these designs, a computer simulation model to study one-dimensional lossless metamaterials is presented as well. This simulation model is based on RLC equivalent circuits. Finally, the necessary conversion equations are presented to compare the LC model with the theoretical results.

Committee:

Sergei F. Lyuksyutov (Advisor); Jutta Luettmer-Strathmann (Committee Chair); Alper Buldum (Committee Member)

Subjects:

Electrical Engineering; Electromagnetics; Electromagnetism; Engineering; Physics; Theoretical Physics

Aditya, PradyumnaLeaky Wave Antenna
Master of Science in Engineering (MSEgr), Wright State University, 2016, Electrical Engineering
The main radiation mechanism in a leaky wave antenna is a travelling wave in a guided structure. The main characteristics of a leaky wave antenna are: light weight, easy to fabricate. Leaky wave antennas have been in use since the 1940s. In this thesis, a portable and powerful leaky-wave antenna is designed, implemented, and demonstrated for scanning application. We change the guiding structure by applying a high dielectric constant material to produce a low-cost, small size, light weight, and high sensitivity leaky-wave antenna. The designed antenna can reach large scan angles with small frequency tuned. High scanning angles can be achieved by slight variation of the operating frequency. The radiation direction of the antenna can be varied with the frequency.

Committee:

Yan Zhuang, Ph.D. (Advisor); Marian Kazimierczuk, Ph.D. (Committee Member); Henry Chen, Ph.D. (Committee Member)

Subjects:

Electrical Engineering; Electromagnetics

Keywords:

Leaky Wave Antenna, Ferro-electric, angular scan rate, ASR

Elghannai, Ezdeen AhmedNOVEL METHOD TO CONTROL ANTENNA CURRENTS BASED ON THEORY OF CHARACTERISTIC MODES
Doctor of Philosophy, The Ohio State University, 2016, Electrical and Computer Engineering
Characteristic Mode Theory is one of the very few numerical methods that provide a great deal of physical insight because it allows us to determine the natural modes of the radiating structure. The key feature of these modes is that the total induced antenna current, input impedance/admittance and radiation pattern can be expressed as a linear weighted combination of individual modes. Using this decomposition method, it is possible to study the behavior of the individual modes, understand them and therefore control the antennas behavior; in other words, control the currents induced on the antenna structure. This dissertation advances the topic of antenna design by carefully controlling the antenna currents over the desired frequency band to achieve the desired performance specifications for a set of constraints. Here, a systematic method based on the Theory of Characteristic Modes (CM) and lumped reactive loading to achieve the goal of current control is developed. The lumped reactive loads are determined based on the desired behavior of the antenna currents. This technique can also be used to impedance match the antenna to the source/generator connected to it. The technique is much more general than the traditional impedance matching. Generally, the reactive loads that properly control the currents exhibit a combination of Foster and non-Foster behavior. The former can be implemented with lumped passive reactive components, while the latter can be implemented with lumped non-Foster circuits (NFC). The concept of current control is applied to design antennas with a wide band (impedance/pattern) behavior using reactive loads. We successfully applied this novel technique to design multi band and wide band antennas for wireless applications. The technique was developed to match the antenna to resistive and/or complex source impedance and control the radiation pattern at these frequency bands, considering size and volume constraints. A wide band patch antenna was achieved using the developed technique. In addition, the technique was applied to multi band wire less Universal Serial Bus (USB) dongle antenna that serves for WLAN IEEE 802.11 a/b/g/n band applications and Radio Frequency Identification (RFID) tag antenna for 915MHz band applications with superior performance compared to previous published results. This dissertation also discusses the total Q of an antenna from the CM standpoint. A new expression as well as additional physical information about each mode's individual contribution to the total antenna Q are provided. Finally, the theory is used to an analyze the antenna in both radiation and/or scattering modes. In the antenna scattering mode, the field scattered by an antenna contains a component that is the short circuit scattered field, and a second component that is proportional to the radiation field. In this dissertation, an analytical study of this phenomena from the CM standpoint is performed aiming to shed some light on antenna scattering phenomenon where additional physical insight is obtained and thus used to reach desire results.

Committee:

Roberto Rojas, Prof (Advisor); Fernando Teixeira, Prof (Committee Member); Robert Burkholder, Prof (Committee Member)

Subjects:

Electrical Engineering; Electromagnetics; Engineering

Keywords:

Antennas; Loaded antennas; Characteristic modes theory; Electrically small antennas; wide band antennas; reactive loading; Antenna scattering; Characteristic modes; Radar cross section; Antenna Scattering; Quality factor of Antennas

Alahmadi, MohammedA Recursive Approach for Adaptive Parameters Selection in A Multifunction Radar
Master of Science, The Ohio State University, 2015, Electrical and Computer Engineering
A multifunction radar is a modern system that is capable of performing multiple radar functions simultaneously, such as surveillance, target tracking, weather monitoring, etc. This class of radar, multifunction radar (MFR), requires a control function, resource manager, to balance the use of its finite resources among the multiple functions. Hence, the multifunction radar performance is limited by the resource manager intelligent behavior to allocate the system resources. This thesis addresses the challenge of using radar resource management (RRM) to provide the attention element of cognition for radar systems. A recursive form of the radar resource allocation problem is proposed that uses prior knowledge about the target to refine the radar parameters every time the radar revisiting the target. This approach enables the radar system to be more sensitive to the change in the environment and therefore adapt its parameters accordingly. The approach is applied to the problem of tracking multiple targets with different RCS configurations. The aim is to minimize the dwell time while achieving an acceptable SNR for track maintenance and while simultaneously maximizing the track update time. This control over the SNR and update rate can be thought of as giving the correct attention to the target track task. The main advantage of this approach is the ability to reduce the radar load allocation while maintaining a desirable SNR. This thesis also describes the design and implementation of a multifunction radar model that is used to support the development of the adaptive parameters selection resource allocation approach. The application of the earliest deadline first approach to schedule track dwells, adaptive update rate, is analyzed in this thesis. It was shown that this approach of resource allocation can only manage a limited number of targets and it is sometimes difficult to allocate resources to continue the surveillance task.

Committee:

Christopher Baker (Advisor)

Subjects:

Electrical Engineering; Electromagnetics; Remote Sensing

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