High-Resolution Millimeter-Wave Tomography System for Nondestructive Testing of Low-Permittivity Materials

Tomographic microwave imaging is employed as a method of nondestructive testing in a wide range of industrial applications, e.g., for quality control. However, many low-permittivity materials, such as gaseous substances or foam with high air content, do not provide sufficient contrast to the environ...

Full description

Saved in:
Bibliographic Details
Published in:IEEE transactions on microwave theory and techniques 2021-01, Vol.69 (1), p.1105-1113
Main Authors: Och, Andreas, Holzl, Patrick A., Schuster, Stefan, Scheiblhofer, Stefan, Zankl, Dominik, Pathuri-Bhuvana, Venkata, Weigel, Robert
Format: Article
Language:English
Subjects:
Air Content
Continuous wave radar
High resolution
Horn antennas
Industrial applications
Inverse problems
Microwave imaging
Microwave theory and techniques
Millimeter waves
Millimeter-wave (mmW) radar
Nondestructive testing
Permittivity
Permittivity measurement
Quality control
Radar
Radar attenuation
radar imaging
Regularization
Sensors
Signal paths
time of arrival estimation
Tomography
Transceivers
Wave attenuation
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Tomographic microwave imaging is employed as a method of nondestructive testing in a wide range of industrial applications, e.g., for quality control. However, many low-permittivity materials, such as gaseous substances or foam with high air content, do not provide sufficient contrast to the environment to be measured with existing systems. This article introduces a 77-79-GHz high-resolution tomography system that facilitates the characterization of materials with relative permittivity close to one and very small attenuation. Fully integrated frequency-modulated continuous-wave radar transceivers are utilized as sensors to reduce the system cost and complexity significantly. The medium-dependent time-of-flight between different radar sensors is evaluated to reconstruct the permittivity distribution inside an area-under-test. To solve the underdetermined inverse problem, two methods based on the Tikhonov regularization and total variation regularization are implemented. Individual impacts on measurement uncertainty are investigated. Custom-designed horn antennas ensure a sufficient number of signal paths between the sensors. A prototype is built using two synchronized radar modules and a rotary stage to emulate a higher number of sensors. System simulations and measurements are conducted utilizing various low-permittivity foam phantoms. Successful reconstructions of the 2-D permittivity distribution demonstrate the feasibility of this approach.
ISSN:0018-9480
1557-9670
DOI:10.1109/TMTT.2020.3030662