Graduation Semester and Year

2017

Language

English

Document Type

Thesis

Degree Name

Master of Science in Computer Science

Department

Computer Science and Engineering

First Advisor

Haiying Huang

Second Advisor

Jean Gao

Abstract

Microstrip antenna-sensor has received considerable interests in recent years due to its simple configuration, compact size, and multi-modality sensitivity. Having a simple and conformal planar configuration, antenna-sensor can be easily attached on the structure surface for Structure Health Monitoring (SHM). As a promising sensor, the resonant frequency of the antenna-sensor is sensitive to different structure properties: such as planar stress, temperature, moisture, pressure and shear. As a passive antenna, antenna-sensor’s resonant frequency can be wirelessly interrogated at a middle range distance without using an on-board battery. However, a major challenge of antenna-sensor’s wireless interrogation is to isolate the antenna backscattering from the back-ground scattering to avoid “self-jamming” problem. To tackle this problem, we have developed an algorithm in order to eliminate back-ground structure backscattering. This study develops antenna-sensor interrogation for simultaneous shear and pressure displacement sensing. A patch antenna was investigated as a shear and pressure sensing unit and an Ultra-Wide Band (UWB) antenna was added as a passive transceiver (Tx/Rx) for the antenna sensor. A microstrip delay line was implemented in sensor node to connect the Tx/Rx antenna and patch antenna-sensor. Due to time delay caused by the delay line, the antenna backscattering can be separated from back-ground scattering in the time domain using time-gating technology. The gated time domain signal was converted into the frequency domain by Fast Fourier Transform (FFT), from which the resonant frequency of antenna-sensor can be determined. Furthermore, we integrated the time-gating technique using the FMCW radar principle to realize FMCW time-gating interrogation technique to achieve a compact portable interrogation unit for wearable applications. The advantage of such an approach is that the time gating is performed in the frequency domain instead of the time domain. As a result, substantial improvement on the interrogation speed and the size of the interrogator can be achieved. The proposed shear/pressure displacement sensor is intended to be used for monitoring the interaction between the human body and assistive medical devices (e.g. prosthetic liners, diabetic shoes, seat cushions) in order to enhance the comfort for the patients.

Keywords

Wireless interrogation, Antenna-sensor, Shear, Pressure, Ultra wide band antenna

Disciplines

Computer Sciences | Physical Sciences and Mathematics

Comments

Degree granted by The University of Texas at Arlington

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