Presenter Information

John M. Liu, United States Navy

Location

La Jolla, CA

Start Date

1-1-1998 12:00 AM

Description

Recently published/ experimental research on microwave NDE of an internal defect has followed either one of two approaches, each with its own advantages and drawbacks [1]. In the first (generally referred to as the far-field approach), a broad, microwave beam is launched from an antenna some distance away from the material (typically, a foot or more). The scattered signal sensed by either the same or another antenna is related to some characteristics of the defect. In the second approach, the transmitting antenna is replaced by an open-ended coaxial line or wave guide. The electromagnetic field generated in the “near-field” of this aperture is modified, when a piece of material with an internal defect is placed adjacent to it. As this “near-field” probe is mechanically scanned over the material with a defect, the resulting changes in the admittance, standing wave ratio, or the amplitude and phase of the reflected signal in the waveguide are related to the characteristics of the defect. This paper describes work using the “far-field” approach.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

17A

Chapter

Chapter 2: Emerging Technologies

Section

Laser/Optical Ultrasonics

Pages

699-703

DOI

10.1007/978-1-4615-5339-7_90

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Microwave Scattering for the Characterization of a Disc-Shape Void in Dielectric Materials and Composites

La Jolla, CA

Recently published/ experimental research on microwave NDE of an internal defect has followed either one of two approaches, each with its own advantages and drawbacks [1]. In the first (generally referred to as the far-field approach), a broad, microwave beam is launched from an antenna some distance away from the material (typically, a foot or more). The scattered signal sensed by either the same or another antenna is related to some characteristics of the defect. In the second approach, the transmitting antenna is replaced by an open-ended coaxial line or wave guide. The electromagnetic field generated in the “near-field” of this aperture is modified, when a piece of material with an internal defect is placed adjacent to it. As this “near-field” probe is mechanically scanned over the material with a defect, the resulting changes in the admittance, standing wave ratio, or the amplitude and phase of the reflected signal in the waveguide are related to the characteristics of the defect. This paper describes work using the “far-field” approach.