Doctoral Dissertations

Keywords and Phrases

Modulated Scatterer Technique (MST)


"Health monitoring of infrastructure is an important ongoing issue. Therefore, it is important that a cost-effective and practical method for evaluating complex composite structures be developed. A promising microwave-based embedded sensor technology is developed based on the Modulated Scatterer Technique (MST). MST is based on illuminating a probe, commonly a dipole antenna loaded with a PIN diode (also referred to as a single-loaded scatterer, or SLS), with an electromagnetic wave. This impinging wave induces a current along the scatterer length, which causes a scattered field to be reradiated. Modulating the PIN diode also modulates the signal scattered by the probe, resulting in two different states of the probe. By measuring this scattered field, information about the material in the vicinity of the probe may be determined. Using the ratio of both states of the probe removes the dependency of MST on several measurement parameters. In order to separate the scattered signal from reflections from other targets present in the total detected signal, a swept-frequency measurement process and subsequent Fourier Transform (time-gate method) was incorporated into MST. Additionally, a full electromagnetic study of the SLS, as applied to MST, was also conducted. The increased measurement complexity and data processing resulting from the time-gate method prompted the development of a novel dual-loaded scatterer (DLS) probe design, with four possible modulation states. By taking a differential ratio, the reflections from other targets can be effectively removed, while preserving the measurement parameter independence of the SLS ratio. A full electromagnetic derivation and analysis of the capabilities of the DLS as applied to MST is included in this investigation, as well as representative measurements using the DLS probe"--Abstract, page iii.


Zoughi, R.

Committee Member(s)

DuBroff, Richard E.
Pommerenke, David
Xiao, Hai, Dr.
Chen, Genda


Electrical and Computer Engineering

Degree Name

Ph. D. in Electrical Engineering


American Society for Nondestructive testing
Missouri University of Science and Technology. University Transportation Center


Missouri University of Science and Technology

Publication Date

Fall 2010


xiv, 153 pages

Note about bibliography

Includes bibliographical references (pages 147-152).


© 2010 Kristen Marie Donnell, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Subject Headings

Detectors -- Computer programs
Electromagnetic waves
Embedded computer systems
Microwave devices
Nondestructive testing

Thesis Number

T 9695

Print OCLC #


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