Ph. D. Dissertation Defense for Yunqiang Yang

College of Engineering
Department of Electrical Engineering and Computer Science
‐ Announcement of a Doctoral Dissertation Defense ‐
Ferris Hall 414
Tuesday, July 15, 2008 @ 9:00 A.M.
“Development of a Real-time Ultra-wideband
See Through Wall Imaging Radar System”
Yunqiang Yang, Ph.D. Candidate
Dr. Aly E. Fathy, Major Professor
Abstract
See-Through-Wall technology has emerged as a must-have enabling technology by both the military and commercial sectors. The use of Ultra-Wideband ??UWB?? in recent years has opened the doors for realizing such fascinating thoughts. The progress in UWB See-Through-Wall technology has been steady and valuable.

As a pioneer in this area, we have led the research in addressing many of the fundamental questions and resolving many of the hurdles in advancing this technology. Here we will briefly mention a few of the concerns that we have addressed: should we carry out our measurements in the frequency or time domain? What is the best operating frequency for wall penetration and obtaining a desired image resolution? In the time domain, can we develop a cost-effective approach to process very narrow pulses, not relying on the expensive solution such as real-time oscilloscope? Is it possible to develop a high-performance stand-alone system to carry out the basic STW measurements? Is it possible to utilize off-the-shelf components to realize such a system with the least design complexity? And finally, can we theoretically model such complicated problems using Advanced EM modeling?

This dissertation is to investigate these challenging areas of which the STW community has great concern, and also produce a realizable high performance STW platform system, which will aid the STW community to find the ultimate answer through experimental and theoretical work. The architectures of a realizable STW imaging system are thoroughly examined and studied in our work. We present both a conceptual system based on RF instruments and a standalone realtime system based on custom design. These developed systems utilize a reconfigurable design architecture, which allows the system to scale down/up to a desired UWB operating frequency with little difficulty. Along the way to a complete STW system, we have developed a simplified transmission line model for wall characteristic prediction; we have developed a scalable design of synthetic aperture array;we have proposed a cost-effective and efficient UWB data acquisition method for real-time STW application based on equivalent-time sampling method. The extensive measurement results reported here include wall characterization, static image formation, and tracking moveable targets behind the wall. Even though digital signal processing to generate radar images is not the major part of this research, simple methods for image formation have been implemented and results are very encouraging.