"Microwave and millimeter wave (300 MHz - 300 GHz) imaging techniques have shown great potential for a wide range of industrial and medical applications. These techniques are fundamentally based on measuring relative and coherent electromagnetic fields distributions, e.g., electric fields, around the object to be imaged. Various imaging systems can be devised for measuring relative electric field distributions; each with it own advantages and limitations. This dissertation is focused on addressing critical challenges related to the practical implementation of various microwave and millimeter wave imaging systems. Specifically, this research is meant to achieve three main objectives related to designing efficient modulated imaging methods/array elements, reducing the sensitivity to standoff distance variations in near-field imaging, and designing a simple and accurate vector network analyzer (VNA) for in-situ imaging applications. The concept of modulating millimeter wave antenna and scatterer structures, directly to increase the overall system sensitivity and reduce the image acquisition time, is central to the development presented herein. To improve upon the conventional modulated scatterer technique (MST) based on dipole scatterers; a new multiple loaded scatterer (MLS) method and novel loaded elliptical slot are introduced and analyzed. A unique near-field differential probe based on dual-loaded modulated single waveguide aperture is developed to compensate for and reduce the effect of standoff distance variations in near-field imaging. Finally, a novel vector network analyzer (VNA) design is introduced to meet the rising need for in-situ vector measuring devices. To realize a robust handheld millimeter wave VNA, a custom-designed waveguide phase shifter based on sub-resonant loaded slots is introduced. The proposed MLS method, modulated elliptical slot, dual-loaded modulated aperture probe, and VNA are thoroughly investigated and their efficacy for microwave and millimeter wave imaging is demonstrated"--Abstract, page iii.
DuBroff, Richard E.
Hale, Barbara N.
Stanley, R. Joe
Electrical and Computer Engineering
Ph. D. in Electrical Engineering
Air Force Research Laboratory (Wright-Patterson Air Force Base, Ohio)
United States. National Aeronautics and Space Administration
Texas Research Institute at Austin
Missouri University of Science and Technology
xiv, 156 pages
© 2009 Mohamed Ahmed AbouKhousa, All rights reserved.
Dissertation - Open Access
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Abou-Khousa, Mohamed A., "Novel modulated antennas and probes for millimeter wave imaging applications" (2009). Doctoral Dissertations. 2005.