A transmission-line metamaterial design of a material-embedded electric line source radiating inside a ground recess is investigated. The media embedding the recessed line source are designed such that the embedded current creates the same radiation pattern as a line source over a flat conducting ground plane. Transmission-line metamaterial unit cell designs for the embedding media obtained from the transformation electromagnetics design technique are shown. The metamaterial design of the overall embedded source configuration is numerically tested using circuit simulations. It is shown that the embedded-source design creates the same radiation characteristics as the line source above a flat ground plane at the design frequency.

This dissertation presents beamforming designs. Using novel techniques and methods, the performance of the beamforming is improved on dual-band, tri-band, flexible function, tunable function in THz, and dynamic controllability on incident wave.

No / Radiation efficiency of antennas is shown to be measurable by a modified radiometric technique where the antenna's physical temperature is varied, rather than the noise temperature of its surroundings. The method is accurate, flexible and much more convenient for routine use. A means of avoiding errors caused by temperature-dependent antenna impedance is described. The accuracy of the method is verified by measuring the radiation efficiency of a horn antenna with a 3 dB attenuator to simulate a 50% efficient antenna, and by using microstrip patch antennas, whose measured efficiencies compared well with values computed from a transmission-line model.

The modulated scattering technique is used in conjunction with a Software Defined Radio (SDR) dongle to obtain a software-based modulated signal output. SDR# is the software package used to get spectrum analysis of the modulated signal. A transmitter yagi antenna sends a 2.304GHz signal on to an antenna connected to a reflector coefficient modulator (700Hz) and the modulated waves are received by another yagi. The receiver yagi antenna is then connected to a frequency converter to convert a 2.304GHz signal to a 144MHz dongle input signal which finally puts the scattered output on computer software with a SDR dongle. The output has a center frequency with modulated spectral lines on either side of the measured frequency. Finally, antenna patterns are measured with different types of antennas by rotating the antennas and observing the baseband modulation sidebands.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 161-164).

Predicting performance metrics for the next-generation of multi-mode and multi-antenna wireless communication systems demands site-specific knowledge of the wireless channel's underlying radio wave propagation mechanisms. This thesis describes the first measurement system capable of characterizing individual propagation mechanisms in situ. The measurement system merges a high-resolution spatio-temporal wireless channel sounder with a new field reconstruction technique to provide complete knowledge of the wireless channel's impulse response throughout a 2-dimensional region. This wealth of data may be combined with space-time filtering techniques to isolate and characterize individual propagation mechanisms. The utility of the spatio-temporal measurement system is demonstrated through a measurement-based investigation of diffraction around building corners. These measurements are combined with space-time filtering techniques and a new linear wedge diffraction model to extract the first semi-mpirical diffraction coefficient. Specific contributions of this thesis are: * The first ultra-wideband single-input multiple-output (SIMO) channel sounder based upon the sliding correlator architecture. * A quasi 2-dimensional field reconstruction technique based upon a conjoint cylindrical wave expansion of coherent perimeter measurements. * A wireless channel ``filming' technique that records the time-domain evolution of the wireless channel throughout a 2-dimensional region. * High-resolution measurements of the space-time wireless channel near a right-angled brick building corner. * The application of space-time filtering techniques to isolate the edge diffraction problem from the overall wireless channel. * An approximate uniform geometrical theory of diffraction (UTD)-style linear model describing diffraction by an impedance wedge. * The first-ever semi-empirical diffraction coefficient extracted from in situ measurement data. This thesis paves the way for several new avenues of research. The comprehensive measurement data provided by channel "filming" will enable researchers to develop and implement powerful space-time filtering techniques that facilitate measurement-based investigations of radio wave propagation. The measurement procedure described in this thesis may be adapted to extract realistic reflection and rough-surface scattering coefficients. Finally, exhaustive measurements of individual propagation mechanisms will enable the first semi-empirical propagation model that integrates empirical descriptions of propagation mechanisms into a UTD-style mechanistic framework.

M. Tech. Electrical Engineering. / Produces findings, based on scientific methods, to verify or refute electromagnetic propagation, generated with Synthetic Poynting Vector formation, that will enable small but efficient electrical antennas.

Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Manos M. Tentzeris; Committee Co-Chair: John Papapolymerou; Committee Member: Andrew F. Peterson; Committee Member: Chang-Ho Lee; Committee Member: John D. Cressler; Committee Member: Joy Laskar.

Thesis (M.Eng.)--Memorial University of Newfoundland, 1999. / Bibliography: leaves [97]-101.

Thesis (M.S.E.E.)--University of Puerto Rico, Mayagüez Campus, 2005. / Tables. Printout. Includes bibliographical references (leaves146-148).