This thesis discusses the theory and limitations of a system that has been designed and constructed for the purpose of measuring the phase shift and attenuation of high-frequency (15 MHZ) electromagnetic waves propagating between two insulated antennas that have been lowered down air-filled boreholes (cased with PVC pipe) at San Xavier Mine, Pima County, Arizona. Both the transmitting and receiving antennas are center-fed, sleeve dipoles that have been tuned to approximately their resonant lengths. The insulated-sleeve dipole antenna is modelled as the inner conductor of a radiating, coaxial transmission-line, which allows simple transmission-line formulas to be used in approximating the antenna impedance and current distribution along the antenna. Experimental results at the San Xavier Mine indicate the analogy is valid. Consequently, the most easily interpreted and repeatable measurements have been made with the antennas centered in the borehole.

Orthogonal frequency division multiplexing (OFDM) is an efficient multi-carrier modulation technique which can be combined with transmitter and receiver diversity communication systems. Maximal ratio combining (MRC) and space-time block coding (STBC) can be used in conjunction with receiver and transmitter diversity in order to increase the communication system's performance. For these systems, channel estimation and tracking must be performed since the receiver requires channel state information for decoding. In this thesis, block-type and comb-type channel estimation algorithms for OFDM systems over multipath fading channels are studied and simulated. Performance results using simulated frequency-selective channels are presented.

The complex permittivity ( )Ì and permeability ( æ) of a material determine the response of the material to electromagnetic radiation. Usually, the real parts of Ì and æ are positive for naturally occurring materials at microwave frequencies. Metamaterials are engineered media that are designed to have either a negative permittivity or permeability or both. Negative permeability and negative permittivity would cause electromagnetic waves traveling through this medium to exhibit unusual characteristics such as power flow in a direction opposite to the phase velocity. In this thesis, the wave matrix approach is used to calculate the total reflection and transmission coefficients of a multilayered structure. The method is applicable to all types of materials, including metamaterials. Several layered configurations are studied including both metamaterial and conventional dielectric layers. A MATLAB program is developed to examine the effects of frequency, angle of incidence and polarization. The results are compared to published data. Potential applications of metamaterials are also discussed.

by Chen Tian Wen. / Thesis submitted in: December 1998. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 84-87). / Text in English; abstract also in Chinese. / by Chen Tian Wen. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation of the Studies --- p.1 / Chapter 1.2 --- Structure of this Thesis --- p.2 / Chapter 2 --- A Brief Review on Sonoluminescence --- p.3 / Chapter 2.1 --- History of SL --- p.3 / Chapter 2.2 --- Experimental conditions and observations --- p.3 / Chapter 2.3 --- Theoretical results --- p.6 / Chapter 3 --- Normal Modes of EM Fields in Spherical Geometry --- p.12 / Chapter 3.1 --- Maxwell's Equations in Vacuum --- p.12 / Chapter 3.2 --- Normal Modes in Spherical Geometry --- p.13 / Chapter 3.2.1 --- Normal Modes in Homogeneous Dielectric Medium --- p.14 / Chapter 3.2.2 --- A Dielectric Sphere Embedded in an Ambient Dielelctric Medium --- p.17 / Chapter 3.2.3 --- Generalization to Layered Spheres --- p.18 / Chapter 4 --- Quantization of EM field and Field-atom Interaction --- p.21 / Chapter 4.1 --- Introduction --- p.21 / Chapter 4.2 --- Quantization of the EM fields --- p.22 / Chapter 4.3 --- Physical Interpretations --- p.24 / Chapter 4.4 --- Dipole Transition Rate in a Dielectric Medium --- p.26 / Chapter 4.5 --- Radiation rate of a dipole inside and outside a homogeneous sphere --- p.28 / Chapter 4.6 --- Summary --- p.45 / Chapter 5 --- SL Models as Layered Spheres --- p.49 / Chapter 5.1 --- Motivation of the Layered Sphere Model --- p.49 / Chapter 5.2 --- A small core and a thick outer layer --- p.50 / Chapter 5.3 --- A large core and a thin outer layer --- p.62 / Chapter 5.4 --- Summary --- p.68 / Chapter 6 --- Realistic Model from Numerical Hydro dynamic simulations --- p.70 / Chapter 6.1 --- The Model --- p.70 / Chapter 6.2 --- Results from Numerical Simulations --- p.73 / Chapter 6.3 --- Summary --- p.79 / Chapter 7 --- Conclusion --- p.81

by Tsang, Yuk-fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 67-68). / by Tsang, Yuk-fai. / Chapter 1 --- Introduction --- p.4 / Chapter 2 --- Uniform accelerated charge radiation --- p.7 / Chapter 2.1 --- An old paradox: Radiate or not? --- p.7 / Chapter 2.2 --- Uniform Accelerating Charge(UAC) --- p.8 / Chapter 2.3 --- EM fields of UAC --- p.9 / Chapter 2.4 --- Radiation of UAC --- p.13 / Chapter 2.5 --- Energy conservation: acceleration energy --- p.14 / Chapter 3 --- Numerical calculation of EM field energy --- p.18 / Chapter 3.1 --- EM fields of UAC --- p.19 / Chapter 3.2 --- Comparison of total EM field energy --- p.23 / Chapter 3.3 --- Results --- p.28 / Chapter 4 --- Modification of the paradox --- p.30 / Chapter 4.1 --- Uniformly accelerated frame (UAF) --- p.30 / Chapter 4.2 --- Radiation in UAF --- p.32 / Chapter 4.3 --- The paradox in another situation --- p.34 / Chapter 5 --- The rotating frame --- p.37 / Chapter 5.1 --- The reference frames --- p.37 / Chapter 5.2 --- Geometric properties of co-rotating frame --- p.38 / Chapter 5.3 --- Maxwell equations in non-inertial frame --- p.41 / Chapter 6 --- Transformation of radiation fields to rotating frame --- p.42 / Chapter 6.1 --- EM fields of a moving charge --- p.43 / Chapter 6.2 --- Dipole radiation --- p.44 / Chapter 6.3 --- Dipole radiation of a rotating charge --- p.45 / Chapter 7 --- Tr ansformation of the complete fields to rotating frame --- p.49 / Chapter 7.1 --- Lienard-Wiechert Fields --- p.49 / Chapter 7.2 --- Determination of R --- p.54 / Chapter 7.3 --- Radiation is a frame-dependent phenomenon --- p.58 / Chapter 7.4 --- Transformation of static field --- p.59 / Chapter 8 --- Conclusions --- p.62 / Chapter 8.1 --- Comparison of the transformation of EM fields / Chapter 8.2 --- Radiation is a frame-dependent phenomenon --- p.64 / Chapter 8.3 --- The concept of photon --- p.65 / Chapter 8.4 --- Problems left --- p.65 / Reference --- p.67

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Thesis (Ph. D.)--Ohio State University, 1980. / Includes bibliographical references (leaves 77-79). Available online via OhioLINK's ETD Center

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 101-109).

In this thesis, to efficiently and accurately model the electromagnetic radiations from electronic and antenna systems, and to analyze the hybrid electromagnetic (EM)-circuit system and the interactions between EM waves and multi-physics systems, a plethora of full-wave approaches are developed. Specifically, a set of frequency-domain methods are proposed in the first part of this thesis to characterize the electromagnetic radiations from device under test (DUT) based on the sampled near-field data. For the first approach, the dyadic Green function (DGF) in the presence of perfectly conducting sphere is expanded by spherical vector wave functions, which is mathematically rigorous. Based on this DGF and the reciprocity theorem, the radiation outside the spherical sampling surface can be accurately predicted with only the tangential components of the electric near-field over this sampling surface. Sometimes for situations where electronic devices are placed in good conductive shielding enclosures with apertures or ventilation slots, only partially planar electric near-field sampling over the apertures or the slots is sufficient according to Schelkunoff’s principle. Due to the unavailability of analytical DGF and the prohibitively computational cost for the numerical DGF, a novel two-step process approach by considering the radiation problem as a scattering issue with incident waves from the equivalent magnetic currents derived from the sampled electric near-field is proposed. However, the very near-field radiation inside the sampling surface cannot be retrieved with the above two approaches. To overcome this limitation, the equivalent source reconstruction based methods are introduced by replacing the radiators with equivalent current sources that are capable of reproducing the original radiation. Due to the difficulty of acquiring the phase information of the near-field data, a fully new iterative phaseless source reconstruction method (SRM) which only needs the amplitude of the electric field is developed. To reduce the computational cost of traditional SRM for broadband radiators, a wideband SRM based on a Stoer-Bulirsh (SB) recursive tabular algorithm is proposed. Enhanced by an adaptive frequency sampling strategy, only a very small number of frequency samples are required. With the purpose to capture the nonlinear response of EM-circuit systems, transient scattering from penetrable objects, surface plasmon polarization (SPP) of grapheme below the terahertz range, and the impacts of random parameters on the physical behavior of stochastic systems, various novel discontinuous Galerkin time-domain (DGTD) based methods and their extensions are developed. For a practical electronic system, apart from the EM part, the presence of lumped elements must be considered. Therefore, a hybrid EM-circuit solver is indispensable. For the EM subsystem governed by Maxwell’s equations, it is solved by DGTD with an explicit time-marching scheme. For the lumped subsystem, circuit equations are constructed based on either the modified nodal analysis (MNA) derived from Kirchoff’s current law or the basic I-V relations. By introducing a port voltage and current, the EM and circuit solvers are synchronized in the temporal sequence at the lumped port. This synchronized EM-circuit solver is free of instabilities even though nonlinear circuit elements are involved. For open-region scattering problem analysis, a novel approach by integrating the time-domain boundary integral (TDBI) algorithm with DGTD is developed. At the truncation boundary, the fields required for the incoming flux in DGTD is calculated using the TDBI from the equivalent currents over a Huygens’ surface enclosing the scatterer. The hybrid DGTD-BI ensures that the radiation condition is mathematically exact and the resulting computation domain is as small as possible since the truncation boundary conforms to scatterer’s shape. By considering the one atom-thick graphene as an infinitesimally thin conductive sheet, a surface impedance boundary condition (SIBC) augmented DGTD algorithm is developed to model the graphene. With this SIBC, straightforward volumetric discretization is avoided, thus significantly reducing the memory cost and meanwhile alleviating the restriction on the minimum time marching size. Due to the complex relation between the surface conductivity σg (comprising contributions from both intraband and interband) and the angular frequency ω, direct mapping the numerical flux from the frequency to the time-domain via inverse Fourier transform is not available. To address this issue, a fast-relaxing vector-fitting (FRVF) technique is used to approximate the σg by rational functions in the Laplace-domain. Via inverse Laplace transform, the time-domain matrix equations are obtained in integral forms of time t. Resorting to finite integral technique (FIT), a fully-discrete matrix system can be achieved. Finally, to consider the impact of random parameters on realistic electronic systems, a stochastic solver based on DGTD and sparse-grid collocation method is developed. To reduce the number of supporting, an adaptive strategy is utilized by using the local hierarchical surplus as error indicator. To improve the flexibility of the proposed algorithm, both piecewise linear and Lagrange polynomial basis functions are employed to handle different stochastic systems. Particularly, the piecewise linear basis function is more efficient for non-smoothly observables while Lagrange polynomials are more suitable for smoothly observables. With these strategies, the singularities and quick variations can be efficiently captured but with very small number of collocation points. The above proposed algorithms are demonstrated by various examples, the accuracy, efficiency, and robustness of these algorithms are clearly observed. / published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

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