Microwave Swept-Frequency Optimization for Accurate Thickness or Dielectric Property Monitoring of Conductor-Baked Composites


A microwave swept-frequency approach is discussed for accurate measurement of thickness and dielectric properties of a conductor-backed dielectric composite. This technique illustrates the importance of frequency selection for maximum measurement sensitivity (resolution). The theoretical foundation, which is based on the radiation of a swept-frequency microwave signal via an open-ended rectangular waveguide into the conductor-backed dielectric, is briefly discussed. The result of several experiments to verify the theory are presented. The results indicate that thickness variations in the order of a few microns or smaller can be monitored at relatively low microwave frequencies (around 10 GHz). Sensitivity to detection of the dielectric property variations is also shown to be frequency-dependent. Important practical aspects of this technique are also discussed.


Electrical and Computer Engineering

Keywords and Phrases

Composite Materials; Dielectric Materials; Microwaves; Optimization; Sensitivity Analysis; Thickness Measurement; Coated Material; Conductor-Backed Composites; Dielectric Property Monitoring; Microwave Swept-Frequency Optimization

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Document Type

Article - Journal

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© 1993 American Society for Nondestructive Testing, Inc., All rights reserved.

Publication Date

01 Jun 1993

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