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Electrical Engineering and Computer Science

Undergraduate Research Selected for IEEE Potentials Magazine

Published on October 31st, 2012 by Michelle Ward

Zengxin Zhang
Zengxin Zhang

EECS senior Zengxin Zhang’s article, “An Alternative Technique for Solving Impedance Matching Problems on the Smith Chart,” has been selected for publication in a special issue of IEEE Potentials Magazine, the student magazine of the Institute of Electrical and Electronics Engineers (IEEE).

In his spare time, Zhang developed a new equation for a longstanding RF engineering tool, the Smith Chart, that is used in the design of analog front-end of systems operating in the RF spectrum, such as wireless communications, radar, and navigation systems.

“First of all, I was surprised. As an undergraduate, I did not think I would have an opportunity to become a published author,” Zhang said. “I definitely received encouragement to work hard and investigate my ideas.”

In Electromagnetics II (EECS 420) last spring, Zhang learned about the Smith chart, which replaces complicated equations with easy-to-decipher circles that depict how circuits, transmission lines, and other components behave at different frequencies. The Smith chart teaches students the underlying calculations and provides them with the means to understand what the system is physically doing. While computer-aided design tools perform most calculations today, the Smith Chart serves as a sanity check of their design, says EECS Associate Professor Shannon Blunt.

Zhang developed equations that would provide more precise answers for intersections of circles within the Smith chart. The circles illustrate resistance and reactance and are dependent upon the position on the transmission line. Matching the impedance of a component, such as an antenna to the transmission line, allows for the maximum transfer of power. While computer-aided design tools achieve the same accuracy, Dr. Blunt credits Zhang for finding his own answer.

“Zengxin’s motivation to explore topics out of his own personal curiosity is highly commendable,” says Dr. Blunt. “His initiative and resourcefulness are hallmarks of what it takes to become a good researcher.”

Zhang brought his equation to Dr. Blunt, who suggested a few ideas and encouraged Zhang to keep working on it over the summer. He did just that and credits EECS Research Professor Fernando Rodriguez-Morales for helping him edit his initial draft. The two worked on it as part of Zhang’s summer internship with the Center for the Remote Sensing of Ice Sheets (CReSIS). His adviser, EECS Professor Ron Hui, helped Zhang revise the article for publication.

“I appreciate the EECS professors’ help on this paper,” Zhang said. “They were quite patient and helped me compile this new method into a research paper. In the other words, it is their abundant help and constructive advice that made this paper possible for publication.”