Microwave chemical sensing using overmoded T-line designs and impact of real-time digitizer in the system

<p>Microwave spectrometers have unique advantages in the ability to determine high resolution features that are specific to a given chemical. Very sharp lines which correspond to quantum states of the chemical allow for unique identification of the chemical. Recent advances have shown the possibility of room temperature microwave spectroscopy analysis in which the data is collected in a short amount of time using broadband chirp pulse Fourier transform microwave (CP-FTMW) spectroscopy. In this report, we explore the design of reduced size spectrometers focusing on the reduction as well as expansion of operation frequency of the microwave analysis cell, where the chemical is analyzed at room temperature. In addition, a new real-time digitizer is used in our system to replace the digital storage oscilloscope and can achieve 1 million coherent averages in 20 seconds. Signal-to-noise ratio can be greatly improved, and we take the advantage of the increased SNR and explore chemical signal strength with low input power, and we also demonstrated simultaneous transmit and receive by implementing an absorptive bandstop filter to the system. This report demonstrates the possibility of a non-laboratory based implementation of a high resolution sensor.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical and Computer Engineering

Year

2014

Author dc:creator

• Huang, Yu-Ting

Contributors dc:contributor

• William J. Chappell
• David B. Janes
• Steven T. Shipman
• Zheng Ouyang

• Electromagnetics and Photonics

Repository record dc:identifier

https://docs.lib.purdue.edu/open_access_dissertations/610

OAI identifier oai:identifier

oai:docs.lib.purdue.edu:open_access_dissertations-1357