Engineering Commons^™

Gain Enhancement Of Dielectric Resonator Loaded Waveguide Antennas With Dielectric Overlays, M. Hakkak, Hossein Ameri Mahabadi

Hossein Ameri Mahabadi

The gain characteristics of a dielectric resonator loaded coaxial probe fed circular waveguide antenna (DRLWA) with overlaying parasitic discs have been investigated experimentally. Results indicate that, when properly spaced, the overlays can enhance the gain by more than 6 dB.

Achieving A Given Reflectance For Unpolarized Light By Controlling The Incidence Angle And The Thickness Of A Transparent Thin Film On An Absorbing Substrate: Application To Energy Equipartition In The Four-Detector Photopolarimeter, R. M.A. Azzam, Kurt A. Giardina

Electrical Engineering Faculty Publications

At a given wavelength λ we determine all possible solution pairs (ϕ, ζ) of the incidence angle ϕ and the thickness ζ of a transparent thin film on an absorbing substrate that achieve a given unpolarized light reflectance R_u. The trajectory of the point that represents a solution pair in the ζ, ϕ plane depends on the optical properties of the film and substrate and on whether R_u is greater than or less than the normal-incidence reflectance -R₀ of the bare substrate. When R_u > - R₀, the specified reflectance is achieved over a …

Three-Dimensional Insulated Gate Bipolar Transistor (Igbt) Development, P.V. Gilbert, G.W. Neudeck

Department of Electrical and Computer Engineering Technical Reports

A new insulated gate bipolar transistor structure, the 3D-IGBT, is presented. The 3D-IGBT utilizes selective epitaxial silicon to form a top contacted anode and still retain the cellular structure of vemcally oriented devices. The 3D-IGBT , unlike other fully integrable power devices, exploits the merits of cellular structure to increase its packing density and thus reduce its on-resistance per unit area. It also eliminates the parasitic JFET resistance found in vertical IGBT's. To integrate the 3D-IGBT with low power devices, the QDI method of device isolation is also presented. QDI uses a combination of JI and DI to electrically isolate …

A Lower-Bound For The Error-Variance Of Maximum-Likelihood Delay Estimates Of Discontinuous Pulse Waveforms, Kurt Louis Kosbar, Andreas D. Polydoros

Electrical and Computer Engineering Faculty Research & Creative Works

A new lower bound is developed for the error variance of maximum-likelihood time-delay estimation when the received signal is a square pulse, corrupted by additive white Gaussian noise. The bound is generated by combining concepts previously developed for a special class of stochastic processes, induced by the signal model. For moderate signal to noise ratios, the new bound is significantly tighter than previously known ones.

Developing Cmmca Flight Profiles For Cruise Missile Tracking, Andrew C. Hachman

Theses and Dissertations

The Air Force has recently acquired two aircraft dedicated for cruise missile tracking. These aircraft, known as the Cruise Missile Mission Control Aircraft (CMMCA), are responsible for collecting data from the missile and United States. Due to tracking and positively controlling the missile during live fire testing over the western the limited tracking radar range and the flight characteristics of the CMMCA, tracking cruise missiles through complex maneuvers is not always possible. A FORTRAN optimization, based on flight simulation and optimal control theory, was written in a prior thesis effort in order to determine optimal CMMCA flight profiles for tracking …

Hardware-Verification Through Logic Extraction, Michael A. Dukes

Theses and Dissertations

A Prolog-based system is described which employs logic-extraction to perform hardware-verification. The extraction rules are built automatically from hierarchical structural VHDL models, enabling the equivalence of a structural VHDL description and a layout specification to be verified. Pin-to-pin critical- path analysis is performed within the logic-extraction process; many noncritical paths are pruned early, making pin-to-pin critical path analysis of large circuits feasible. It is demonstrated that a design methodology based on logic extraction, VHDL, and a layout tool can provide a fabricated functionally- correct IC design without circuit-level or switch-level simulation. This methodology is shown to be practical for VLSI …

Design And Analysis Of Electrical Circuits That Produce Fractional-Order Differentiation, Richard N. Hughes

Theses and Dissertations

Two half-order differentiator circuit designs were investigated and their electrical performance evaluated (Oldham and Oldfield). Initially, each circuit design was computer modelled and simulated using the HSPICE computer analysis program. Then, each circuit design (Oldham and Oldfield) was fabricated with two different component technologies. This resulted in four circuits, realized on printed circuit boards, to be evaluated--Oldham discrete component; Oldham hybrid component; Oldfield discrete component; and Oldfield surface mount component. The characterizations of each circuit's electrical performance is documented with time, phase, gain, noise and spectrum responses. A comparison of each circuit's performance versus the design criteria and computer model …

Finding A Maximum-Density Planar Subset Of A Set Of Nets In A Channel, Ronald I. Greenberg, Jau-Der Shih

Computer Science: Faculty Publications and Other Works

We present efficient algorithms to find a maximum-density planar subset of n 2-pin nets in a channel. The simplest approach is to make repeated usage of Supowit's dynamic programming algorithm for finding a maximum-size planar subset, which leads to O(n^3) time to find a maximum-density planar subset. But we also provide an algorithm whose running time is dependent on other problem parameters and is often more efficient. A simple bound on the running time of this algorithm is O(nlgn+n(t+1)w), where t is the number of two-sided nets, and w is the number of nets in the output. Though the worst-case …

Model-Based Target Recognition Using Laser Radar Imagery, Robert Y. Li

Department of Electrical and Computer Engineering: Faculty Publications

Autonomous target recognition can be assisted by using CO2 laser radar data. Of these data, range data provide 3-D geometric information and Doppler data boundaries of moving targets. A powerful 3-D feature extraction algorithm based on the Hough transform is used to obtain the orientations and dimensions of the target. This information is then utilized by an inference procedure that recognizes targets based on the available evidence from the sensory data. The experimental results using actual laser radar imagery are successful and the procedure can be used for the future development of a model-based system for target recognition.

Transient Stability Test Systems For Direct Stability Methods, V. Vittal, D Martin, R Chu, J Fish, J C. Giri, C K. Tang, F. Eugenio Villaseca, R G. Farmer

Electrical and Computer Engineering Faculty Publications

A standard set of power system data with benchmark results are presented against which direct stability techniques to assess transient stability can be compared and tested. The test systems have been selected to display a wide range of dynamic characteristics to provide a robust test of the efficacy and accuracy of the various analytical techniques to analyze transient stability. Transient stability test system data and benchmark results obtained from two commercially available time-domain stability analysis packages are presented

Analysis Of Algorithms For Velocity Estimation From Discrete Position Versus Time Data, Ronald H. Brown, Susan C. Schneider Phd, Michael G. Mulligan

Electrical and Computer Engineering Faculty Research and Publications

Algorithms for constructing velocity approximations from discrete position versus time data are investigated. The study is limited to algorithms suitable to provide velocity information in discrete-time feedback control systems such as microprocessor-based systems with a discrete position encoder. Velocity estimators based on lines per period, reciprocal-time, Taylor series expansion, backward difference expansions, and least-square curve fits are presented. Based on computer simulations, comparisons of relative accuracies of the different algorithms are made. The least-squares velocity estimators filtered the effect of imperfect measurements best, whereas the Taylor series expansions and backward difference equation estimators respond better to velocity transients.

Series Compensation Investigation On The Hydro-Quebec And Nypa 765 Kv Transmission System : Modeling And Stability Analysis, Hans J. Candia

Theses

This thesis presents a mathematical approach for raising the power steady state stability limit by adding series capacitive compensation to a transmission line. The effect of series capacitive compensation and degree of compensation were investigated in detail. The power system studied includes an automatically controlled power system, IEEE Type I.

The results of the actual and theoretical steady state stability limits for a given series capacitance location and degree of compensation were obtained by applying the frequency domain technique. The natural frequencies of each compensated power network were examined.

The best location for series capacitive compensation is proposed which is …

Efficient Hypercube Communications, Shreyas R. Bhatt

Theses

Hypercube algorithms may be developed for a variety of communication-intensive tasks such as sending a message from one node to another, broadcasting a message from one node to all others, broadcasting a message from each node to all others, all-to-all personalized communication, one-to-all personalized communication, and exchanging messages between nodes via fixed permutations. All these communication patterns are special cases of many-to-many personalized communication. The problem of many-to-many personalized communication is investigated here.

Two routing algorithms for many-to-many personalized communication are presented here. The algorithms proposed yield very high performance with respect to the number of time steps and packet …

Ion Exchanged Glass Waveguides With Efficient Coupling To Fibers And Lasers, Shiqing Hu

Theses

To be of practical use in optical communications networks, optical components must have both low on-chip losses and efficient coupling to fibers, semiconductor lasers and detectors. In this thesis work two types of channel waveguides were designed and fabricated on BK7 glass substrate using a low-cost ion-exchange process. The first type of waveguide was formed in a simple sequence of ion-exchange and post-exchange annealing. These single mode waveguides had large mode size and were efficiently coupled to single mode fibers. The lowest loss achieved in fiber-guide direct coupling was 1.25 dB. The second type of waveguide was formed in a …

Conditional Artificial Dielectric : Optically Controlled Microwave Modulator, J. Manuel Jimenez

Theses

A conditional artificial dielectric with embeddings of either CdS, GaAs or Si in PMMA form the dielectric material of a microstrip in a homodyne microwave detection system. The system consists of a Michelson or Mach-Zehnder interferometers with the microstrip placed in one arm. The index of refraction of the microstrip substrate is modulated by chopped incident light causing amplitude and phase variations in the incoming RF signal. Those variations are detected by mixing the light modulated microwave carrier(information channel) with the unmodulated carrier (reference channel) in the interferometer. The output is sensed by the square law detector and a lock-in …

Improved Crystalline Quality Of Si1-XGeX Formed By Low-Temperature Germanium Ion Implantation, Ken-Ichi Shoji, Akira Fukami, Takahiro Nagano, Takashi Tokuyama, Cary Y. Yang

Electrical and Computer Engineering

Improvement of crystalline quality in Si_1-xGe_x formed by germanium ion implantation has been found. End‐of‐range defects were drastically reduced in number by lowering the substrate temperature during implantation with doses on the order of 1016 cm−2. This improvement was confirmed by electrical characterization of p‐n junctions formed in the SiGe layer as well as by transmission electron microscopy.

All Optical Synchronisation With Frequency Division Using A Self Pulsating Laser Diode, Gerald Farrell, P. Phelan, Joe Hegarty

Articles

A master optical clock from a mode locked laser is distributed to two slave twin section lasers. One slave laser divides the optical modulation frequency by 2, the other slave laser multiplies the frequency by 2. It is also possible to vary the multiplication4ivision ratio in a slave laser using only DC control of the absorber of the twin section laser.

Principal Linear Polarization States Of An Optical System, R. M.A. Azzam

Electrical Engineering Faculty Publications

The constraint on the Jones matrix of an optical system such that there exist two linear polarization states at its input that are mapped onto two corresponding linear states at its output is derived. These principal linear polarization (PLP) states, which characterize a broad range of systems, are also found in terms of the Jones matrix elements. Special cases when the PLP states are orthogonal, collapse onto one state, or become infinite in number are indicated. For a deterministic or nondeterministic optical system described by a Mueller matrix, the existence of two PLP states places a constraint on only 3 …

Minority Hole Mobility In N+ Gaas, Michael L. Lovejoy, Michael R. Melloch, Mark S. Lundstrom, R. K. Ahrenkiel

Department of Electrical and Computer Engineering Faculty Publications

The minority hole diffusivity, or equivalently the hole mobility, was measured in n⁺GaAs with the zero‐field time‐of‐flight technique. The minority hole mobility was measured for the donor doping range of 1.3×10¹⁷ cm⁻³ to 1.8×1018 cm⁻³ and was found to vary from 235 to 295 cm²/V s. At the lower doping level, the minority hole mobility is comparable to the corresponding majority hole mobility, but at 1.8×10¹⁸ cm⁻³ the minority hole mobility was 30% higher than the majority carrier hole mobility. These results have important implications for the design of devices such …

Self‐Consistent Scattering Matrix Calculation Of The Distribution Function In Semiconductor Devices, Mark A. Stettler, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

The scattering matrix approach is a new technique for solving the Boltzmann equation in devices. We report a self-consistent application of the technique to realistic silicon devices exhibiting strong nonlocal effects. Simulation of a hot-electron, n-i-n diode demonstrates that the new technique efficiently and accurately reproduces Monte Carlo results without the statistical noise, allowing much tighter convergence with Poisson’s equation.

Microsecond Lifetimes And Low Interface Recombination Velocities In Moderately Doped N-Gaas Thin Films, Gregory Benedict Lush, D. H. Levi, H. F. Macmillan, Michael R. Melloch, Mark S. Lundstrom, R. K. Ahrenkiel

Department of Electrical and Computer Engineering Faculty Publications

We have observed lifetimes greater than 1 ps in moderately doped, thin film, n-GaAs/A1a,Gae,As double heterostructure membranes formed by etching away the substrate. We attribute these ultralong lifetimes to enhanced photon recycling caused by the removal of the substrate. Nonradiative recombination in the bulk and at the interfaces is very low; the upper limit of the interface recombination velocity is 25 cm/S.-Such long lifetimes in GaAs doped at N,= 1.3 X 10” cme3 suggest that thin-film solar cells offer a potential option for achieving very high efficiencies.

Comparative Study Of Minority Electron Properties In P+-Gaas Doped With Beryllium And Carbon, Michael L. Lovejoy, Michael R. Melloch, Mark S. Lundstrom, R. K. Ahrenkiel, B. M. Keyes, T. J. De Lyon, J. M. Woodall

Department of Electrical and Computer Engineering Faculty Publications

Minority electron properties in p+‐GaAs doped with beryllium (Be) and with carbon (C) are reported. Measurements of essentially identical responses for structures differing only in dopant element demonstrate that the diffusivity (Dn) and the diffusion lengths (Ln) are the same in p+‐GaAs doped to ∼1019 cm−3 with Be‐ and C‐dopants. Zero‐field time‐of‐flight analysis yields Dn=35 cm2/s and internal quantum efficiency analysis yields Ln=2.4 μm, which implies a lifetime that is approximately at the estimated radiative limit. In addition, the majority Hall mobility was also found to be identical …

A Study Of Minority Carrier Lifetime Versus Doping Concentration In N‐Type Gaas Grown By Metalorganic Chemical Vapor Deposition, Gregory Benedict Lush, H. F. Macmillan, B. M. Keyes, D. H. Levi, Michael R. Melloch, R. K. Ahrenkiel, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

Time‐resolved photoluminescence decay measurements are used to explore minority carrier recombination in n‐type GaAs grown by metalorganic chemical vapor deposition, and doped with selenium to produce electron concentrations from 1.3×10¹⁷ cm⁻³ to 3.8×10¹⁸ cm⁻³. For electron densities n₀<10¹⁸ cm⁻³, the lifetime is found to be controlled by radiative recombination and photon recycling with no evidence of Shockley–Read–Hall recombination. For higher electron densities, samples show evidence of Shockley–Read–Hall recombination as reflected in the intensity dependence of the photoluminescence decay. Still, we find that radiative recombination and photon recycling are important for …

Minority Electron Transport In Inp/Ingaas Heterojunction Bipolar Transistors, Paul Dodd, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

Electron transport across the base of InP/InGaAs heterojunction bipolar transistors is examined by Monte Carlo simulation. The base transit times and electron distribution functions are examined as a function of basewidth. Clear ballistic behavior is observed only for extremely thin bases (much less than 100 A). Over the range of basewidths of interest for devices, base transport appears diffusive, but the electrons are very far from thermal equilibrium. The diffusive behavior is shown to arise from the sensitivity of the steady-state carrier population to small amounts of large-angle scattering.

Electromagnetic Focusing Properties Of Chirped Metallic Gratings, Jeffrey C. Schmidt

Retrospective Theses and Dissertations

The focusing properties of chirped diffraction gratings have long been studied and often used in applications at optical frequencies. Chirped metallic gratings of this type have also been studied theoretically at microwave frequencies, but no attempt has been made to experimentally examine or utilize the focusing properties of these structures at microwave frequencies. This thesis presents an experimental analysis of the focusing properties of chirped metallic gratings. These gratings are designed to focus electromagnetic energy at a predetermined position by varying strip width and spacing as a function of position. The diffraction gratings are characterized, and experimentally measured results are …

Efficient Simulation Of Multi-Carrier Digital Communication Systems In Nonlinear Channel Environments, K. W. Schneider, William H. Tranter

Electrical and Computer Engineering Faculty Research & Creative Works

For systems that contain both frequency division multiplexing and bandpass nonlinearities, the high sampling rate that is necessary for accurate simulation contributes to the long runtimes. A partial sum of products (ParSOP) method is proposed to reduce the sampling rate of such systems. The ParSOP method allows the simulation sampling frequency to be reduced by only generating those intermodulation products that are centered in the bandwidth of the single observed modulated subcarrier. Simulation results, obtained by using the complex power series nonlinear model on a filtered binary phase shift keying system, showed that a reduction in the simulation runtime by …

Acuta: A Case For Change

ACUTA: Other Publications

In This Issue

Preface

Executive Summary

Societal Trends

The Information Age

The University of the 21st Century

Implications for Telecommunications Administrators

New Emc Design Guidelines For Multilayer Printed Wiring Boards, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

Optimizing The Integration Of Photovoltaic Systems With Electric Utilities, Badrul H. Chowdhury

Electrical and Computer Engineering Faculty Research & Creative Works

The author introduces a comprehensive simulation package whereby the optimal size, operation, performance and economics of a photovoltaic (PV) system can be determined in the utility-integrated mode. The central issue is to present a single definitive optimization model. A stepwise analytical methodology starting at the solar resource and culminating in the value of the PV system in terms of avoided costs is provided. The methodology includes processing of the solar irradiance; identification of the PV system''s configuration and operational features; identification of real-time system controls in the presence of PV generation; security assessment in the presence of PV and production …

An Optical Adaptive Resonance Neural Network Utilizing Phase Conjugation, Donald C. Wunsch, D. J. Morris, T. P. Caudell, R. A. Falk

Electrical and Computer Engineering Faculty Research & Creative Works

An adaptive resonance (ART) device has been conceived that is fully optical in the input-output processing path. It is based on holographic information processing in a phase-conjugating crystal. This sets up an associative pattern retrieval in a resonating loop utilizing angle-multiplexed reference beams for pattern classification. A reset mechanism is used to reject any given beam, allowing an ART search strategy. The design is similar to an existing nonlearning optical associative memory, but it does allow learning and makes use of information the other device discards. This device is expected to offer higher information storage density than alternative ART implementations.