A method and apparatus are presented for generating suppressed carrier digital clock signals. These clock signals have the advantage of being broad band in nature and thus exhibiting lower power spectral density. Structures or systems utilizing such clock signals would be less likely to create electromagnetic noise of sufficient intensity to interfere with radio frequency systems and services. The apparatus requires only digital logic devices, rather than the analog devices required for frequency- or phase-modulated spread spectrum clock generators. The method provides the opportunity to synchronously demodulate the clock, thus restoring the original narrow band clock signal where required. The apparatus was implemented in a programmable gate array using 20 MHz and 33.33 MHz fundamental clocks. Measurements of the resulting electronic spectra and clock jitter are reported. / Graduation date: 1999

Graduation date: 1999

Conducted Electromagnetic Interference (EMI) is a major cause of concern in switchmode power supplies (SMPS) which commonly use standard pulsewidth modulation (PWM). In this thesis, Sigma-Delta (����) modulation is proposed as an alternative switching technique to reduce conducted EMI from SMPS. The result of using ���� modulation is a spread in the spectrum of the conducted emissions so that large concentrations of power at discrete frequencies are avoided. Experimental time-domain waveforms and spectra of the switching function from first-order and second-order ���� modulators are presented to prove the viability of the scheme in EMI mitigation. These modulators are then applied to an off-the-shelf computer power supply and experimental results using FCC-specified methods show a reduction of roughly 5-10dB in EMI emissions over standard PWM modulators. / Graduation date: 1999

Electromagnetic scattering by 3-D arbitrarily shaped homogeneous dielectric objects is characterized. In the analysis, the method of moments is first employed to solve the combined field integral equation for scattering properties of these three-dimensional homogeneous dielectric objects of arbitrary shape. The fast multipole method, and the multi-level fast multipole algorithm are implemented into our codes for matrix-vector manipulations. Specifically, four proposals are made and discussed to increase convergence and accuracy of iterative procedures (conjugate gradient method). Numerical results are obtained using various methods and compared to each other. / Singapore-MIT Alliance (SMA)

A.D. Berk. / "February 11, 1955." / Bibliography: p. 59. / Army Signal Corps Contract DA36-039 SC-64637 Project 102B Dept. of the Army Project 3-99-10-022

Andreas Tonning. / "May 13, 1952." / Bibliography: p. 11. / Army Signal Corps Contract No. DA36-039 sc-100 Project No. 8-102B-0. Dept. of the Army Project No. 3-99-10-022.

N.G. Parke, III. / "June 30, 1948." / Includes bibliographical references. / Army Signal Corps Contract No. W-36-039 sc-32037.

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: James Kolodzey, Electrical and Computer Engineering. Includes bibliographical references.

Thesis (M.E.E.)--University of Delaware, 2006. / Principal faculty advisor: James Kolodzey, Electrical and Computer Engineering. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.