<abstract xmlns="http://www.w3.org/1999/xhtml"><p>The electrical properties of many materials are closely related to their composition and to their moisture content in particular. For sensor development, characterising the response of a particular volume of material over a broad frequency range is desirable, since separate measurements could generate errors due to spatial variability. A coaxial probe has been designed for measurement of the permittivity of smooth and flat, solid or liquid samples over the frequency range from 1 Hz to 6 GHz. Although the probe is capable of a very wide frequency range, separate instruments are generally required, and here we focus on measurements above 1MHz. We demonstrate measurements in the frequency domain using a vector network analyser, and in the time domain using a broadband oscilloscope. For switching, we employed a coaxial switch and demonstrate how that is included within the instrument calibration. Calibration of the probe used three References: an open circuit, short circuit (indium foil) and a reference liquid, ideally chosen for a permittivity similar to that of the sample. The sample complex permittivity was calculated by a numerical model which used as inputs, the measured reflection coefficient and physical measurements of the probe geometry.</p></abstract>

The electrical properties of many materials are closely related to their composition and to their moisture content in particular. For sensor development, characterising the response of a particular volume of material over a broad frequency range is desirable, since separate measurements could generate errors due to spatial variability. A coaxial probe has been designed for measurement of the permittivity of smooth and flat, solid or liquid samples over the frequency range from 1 Hz to 6 GHz. Although the probe is capable of a very wide frequency range, separate instruments are generally required, and here we focus on measurements above 1MHz. We demonstrate measurements in the frequency domain using a vector network analyser, and in the time domain using a broadband oscilloscope. For switching, we employed a coaxial switch and demonstrate how that is included within the instrument calibration. Calibration of the probe used three References: an open circuit, short circuit (indium foil) and a reference liquid, ideally chosen for a permittivity similar to that of the sample. The sample complex permittivity was calculated by a numerical model which used as inputs, the measured reflection coefficient and physical measurements of the probe geometry.

A Broadband Spectroscopic Sensor Probe

International Journal on Smart Sensing and Intelligent Systems

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

{"article-title":"A Broadband Spectroscopic Sensor Probe"}

The electrical properties of many materials are closely related to their composition and to their moisture content in particular. For sensor development,...

A Broadband Spectroscopic Sensor Probe

Published Online: Dec 13, 2017

Page range: 459 - 469

DOI: https://doi.org/10.21307/ijssis-2017-301

Keywords
coaxial probe, spectroscopy, calibration, broadband, network analyser

© 2008 I M Woodhead et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

A Broadband Spectroscopic Sensor Probe

Published Online: Dec 13, 2017

Page range: 459 - 469

DOI: https://doi.org/10.21307/ijssis-2017-301

Keywordscoaxial probe, spectroscopy, calibration, broadband, network analyser

© 2008 I M Woodhead et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Keywords
coaxial probe, spectroscopy, calibration, broadband, network analyser