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Miniaturized Antennas and Metamaterial-Based Transmission Line Components in Microwave Circuits Applications

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What
  • PhD Defenses
When Oct 12, 2010
from 10:00 AM to 11:00 AM
Where Engr IV Room 57-124
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Pei-Ling Chi
Advisor: Tatsuo Itoh

Tuesday, October 12, 2010 at 10:00am
Engr IV Room 57-124

Abstract:
This seminar is focused on two diversities of miniaturization approaches to the antennas and microwave passive circuit components.

The first approach is based on the unique metamaterial transmission line structures. The metamaterial structure or the left-handed structure is an artificial structure that is dispersion engineerable from its constituent parameters. By means of the left-handed transmission lines or the composite right/left-handed (CRLH) transmission lines to replace the conventional microstrip lines, microwave circuit components can be miniaturized via controlling the phase responses at the frequencies of interest, which saves the footprint size. Specifically, this idea was implemented on the dual-band 180o and 90o hybrid couplers and both of them demonstrate considerable size reductions in the experiments.

The second methodology leading to miniaturization is taking advantage of the slow wave structures. The slow wave structures are formed using the capacitive loading periodically. The effective propagation constant is enhanced by increasing the effective shunt capacitance in the equivalent circuit model derived from the conventional transmission line theory. The associated guided wavelength is therefore decreased and the same physical structure is capable of operating at lower frequencies. The slow wave structures are employed for compact antenna applications. In particular, the slow wave enhancement factor (SWE), which is defined as the ratio of the loaded to the unloaded propagation constants ( / 0), is investigated using the loaded unit cell of the equivalent transmission line model and utilized as a design tool for an arbitrary size reduction. It is shown that the SWE agrees very well with miniaturization factor, and therefore load parameters in the circuit model can be readily obtained when a specific size reduction is attempted.

Biography:
Pei-Ling Chi received her B.S. and M.S. degrees from the Department of Communication Engineering and Graduate Institute of Communication Engineering, National Chiao Tung University (NCTU), Taiwan, in 2004 and 2006, respectively. Her research is focused on the analysis and design of miniaturized antennas and metamaterial microwave circuits. She was a recipient of the 2004 Research Creativity Award from the National Science Council (NSC). She has been a student member of the IEEE since 2008.

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