Non-destructive permittivity measurement of solid materials

An open-coaxial probe suitable for measuring the permittivity of solid materials has been designed and tested. The peculiar structure of the probe allows an easy and firm contact with the surface of the material under measurement, resulting in highly reliable and reproducible dielectric measurements. The permittivity measurement is absolute, as the calibration procedure - based on a genetic algorithm - does not require the use of dielectric standards. The measurement system - including the probe, a network analyser, and the numerical code to determine the permittivity from reflection measurements - have been tested on solid materials of known properties, and used for determining the dielectric characteristics of several types of wood.

[1]  Liu Liping,et al.  Measurement of Dielectic Properties of Biological Substances Using Improved Open-Ended Coaxial Line Resonator Method , 1987, 1987 IEEE MTT-S International Microwave Symposium Digest.

[2]  David E. Goldberg,et al.  Genetic Algorithms in Search Optimization and Machine Learning , 1988 .

[3]  S. S. Stuchly,et al.  Permittivity measurements using open-ended sensors and reference liquid calibration-an uncertainty analysis , 1992 .

[4]  Kenneth R. Foster,et al.  Noninvasive electrical characterization of materials at microwave frequencies using an open-ended coaxial line: test of an improved calibration technique , 1990 .

[5]  Nathan Marcuvitz.  Waveguide Handbook , 1951 .

[6]  S. Priori,et al.  A Portable Microwave System for Woodworm Disinfestation of Artistic Painted Boards , 1997 .

[7]  C. Gabriel,et al.  Admittance models for open ended coaxial probes and their place in dielectric spectroscopy. , 1994, Physics in medicine and biology.

[8]  D. E. Goldberg,et al.  Genetic Algorithms in Search , 1989 .

[9]  Brian C. Wadell,et al.  Transmission Line Design Handbook , 1991 .

[10]  A. Yaghjian.  Electric dyadic Green's functions in the source region , 1980 .

[11]  William H. Press,et al.  Numerical Recipes: FORTRAN , 1988 .

[12]  S. S. Stuchly,et al.  Dielectric measurements using a rational function model , 1994 .

[13]  F. E. Gardiol,et al.  Reflection of an open-ended coaxial line and application to nondestructive measurement of materials , 1981, IEEE Transactions on Instrumentation and Measurement.

[14]  A Ignesti,et al.  Dielectric Properties of Wood from 2 to 3 GHz , 2000, The Journal of microwave power and electromagnetic energy : a publication of the International Microwave Power Institute.