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A time domain transmission measurement system for dielectric characterizations

Published online by Cambridge University Press:  19 April 2012

Bianca Will*
Affiliation:
Institute of Microwave Systems, Ruhr-University Bochum, Universitätsstr. 150, 44801 Bochum, Germany. Phone: +49 234 32 26983.
Michael Gerding
Affiliation:
Institute for Electronic Circuits, Ruhr-University Bochum, Universitätsstr. 150, 44801 Bochum, Germany.
Christian Schulz
Affiliation:
Institute of Microwave Systems, Ruhr-University Bochum, Universitätsstr. 150, 44801 Bochum, Germany. Phone: +49 234 32 26983.
Christoph Baer
Affiliation:
Institute for Electronic Circuits, Ruhr-University Bochum, Universitätsstr. 150, 44801 Bochum, Germany.
Thomas Musch
Affiliation:
Institute for Electronic Circuits, Ruhr-University Bochum, Universitätsstr. 150, 44801 Bochum, Germany.
Ilona Rolfes
Affiliation:
Institute of Microwave Systems, Ruhr-University Bochum, Universitätsstr. 150, 44801 Bochum, Germany. Phone: +49 234 32 26983.
*
Corresponding author: B. Will Email: [email protected]

Abstract

Delay time measurements are a commonly used technique for the characterization of dielectric materials. Especially with regard to the characterization of water–solid mixtures like soil or grain delay time measurements, e.g., time domain reflectometry offers a powerful method. However, the accuracy of reflection measurements is limited due to multiple reflections caused by inhomogenities of the environmental material of the sensor. This contribution deals with an improved sensor design based on time domain transmission (TDT) measurements. Thus, the first received impulse includes the necessary information. Multiple reflections are received at later time steps and their influence on the measurement accuracy is nearly negligible. To improve the performance and the applicability of the designed sensor, a cost–efficient TDT system is designed, which is integrated in the sensor. Additionally, a so-called “concentric reversion coupler” is used, which offers the possibility to perform TDT measurements without the necessity of external measuring ports.

Type
Research Papers
Copyright
Copyright © Cambridge University Press and the European Microwave Association 2012

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References

REFERENCES

[1]Nyfors, E.: Industrial microwave sensors–a review. Subsurface Sensing Technol. Appl., 1 (2000), 2343.Google Scholar
[2]Robinson, D.; Jones, S.; Wraith, J.; Or, D.; Friedman, S.: A Review of Advances in Dielectric and Electrical Conductivity Measurement in Soils Using Time Domain Reflectometry. Vadose Zone J., 2 (2003), 444475.CrossRefGoogle Scholar
[3]Kupfer, K.: Electromagnetic Wave Interaction With Water And Moist Substances, Springer, Berlin, 2005.CrossRefGoogle Scholar
[4]Topp, G.; Davis, J.; Annan, A.: Electromagnetic determination of soil water content: Measurements in coaxial transmission lines. Water Resources Res., 16 (1980) 574582.CrossRefGoogle Scholar
[5]Harlow, R.; Burke, E.; Ferre, T.; Bennett, J.; Shuttleworth, W.: Measuring spectral dielectric properties using gated time domain transmission measurements. Vadose Zone J., 2 (2003), 424.CrossRefGoogle Scholar
[6]Will, B.; Gerding, M.; Musch, T.; Rolfes, I.: Determination of Soil Moisture Based on an Improved Sensor Design Using Time Domain Transmission Measurements, in 41st European Microwave Conf., Manchester, UK, 2011.Google Scholar
[7]Burke, E.; Harlow, R.; Ferre, T.: Measuring the dielectric permittivity of a plant canopy and its response to changes in plant water status: An Application of Impulse Time Domain Transmission. Plant Soil, 268 (2005), 123133.CrossRefGoogle Scholar
[8]Blonquist, JM. Jr; Jones, SB.; Robinson, DA.: A time domain transmission sensor with TDR performance characteristics. J. Hydrol., 314 (2005), 235245.CrossRefGoogle Scholar
[9]Will, B.; Gerding, M.: A Time Domain Transmission Method for the Characterization of Inhomogeneous Dielectric Materials, in Asia-Pacific Microwave Conf. 2009, Singapore, 2009.Google Scholar
[10]Ida, N.: Propagation of plane waves in materials, in Engineering Electromagnetics, Springer Verlag, New York, 2000, 764785.CrossRefGoogle Scholar
[11]Bittelli, M.; Salvatorelli, F.; Rossi Pisa, P.: Correction of TDR-based soil water content measurements in conductive soils. Geoderma, 143 (2008), 133142.CrossRefGoogle Scholar
[12]Jones, S.B.; Wraith, J.M.; Or, D.: time domain reflectometry measurement principles and applications. Hydrol. Process., 16 (2002), 141153.CrossRefGoogle Scholar
[13]Noborio, K.: Measurement of soil water content and electrical conductivity by time domain reflectometry: a review. Comput. and Electron. Agric., 31 (2001), 213237.CrossRefGoogle Scholar