Constitutive parameter measurements of fluids and soil between 500 kHz and 5 MHz using a transmission line technique

Kraft, C.

doi:10.1029/jb092ib10p10650

Cited by 19 publications

(25 citation statements)

References 12 publications

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“…The scattering parameter (S11) was obtained from the VNA, and it was converted to permittivity using the procedure of Logsdon and Laird (2002) and Logsdon (2005), who based their procedure on that of Campbell (1990) and Kraft (1987). First, S11 was converted to electrical conductivity:…”

Section: Sensor Designmentioning

confidence: 99%

Short, Multineedle Frequency Domain Reflectometry Sensor Suitable for Measuring Soil Water Content

Logsdon

Horton

2012

Soil Science Soc of Amer J

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Time domain reflectometry (TDR) is a well‐established electromagnetic technique used to measure soil water content. Time domain reflectometry sensors have been combined with heat pulse sensors to produce thermo‐TDR sensors. Thermo‐TDR sensors are restricted to having relatively short needles to accurately measure soil thermal properties. Short needle lengths, however, can limit the accuracy of the TDR measurement of soil water content. Frequency domain reflectometry (FDR) sensors are an alternative to TDR sensors that can provide an inexpensive measurement of soil water content. The objective of this study was to determine whether short FDR sensors can accurately measure soil water content. We designed and constructed a short FDR sensor. For four soil types across a range of water contents, temperatures, and salt contents, we measured soil dielectric spectra with the short FDR sensor. A vector network analyzer was used to obtain soil dielectric spectra in the 1‐MHz to 3‐GHz frequency range. The ideal frequency of a short FDR sensor is the frequency at which the permittivity is not altered by changing temperature or salt content. The 47‐ to 200‐MHz range was an ideal frequency range for measuring soil water content, and 70 MHz was the frequency least influenced by temperature and salt content. The short FDR sensor provided quick, continuous, stable, and cheap measurements of soil water content. Because of the promising performance of the short thermo‐FDR sensor in laboratory studies, sensors should be evaluated in future field studies.

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Section: Sensor Designmentioning

confidence: 99%

Short, Multineedle Frequency Domain Reflectometry Sensor Suitable for Measuring Soil Water Content

Logsdon

Horton

2012

Soil Science Soc of Amer J

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“…The real part of the impedance is due to the electrical loss and the imaginary part is linked to the dielectric constant of the liquid. This cell is inspired by cells used in soil humidity measurement [11]. …”

Section: A Wideband Electromagnetic Sensormentioning

confidence: 99%

New wideband electromagnatic on-line system for microalgae production monitoring

Xi¹,

Roucaries²,

Besse³

et al. 2015

2015 Conference on Cosmetic Measurements and Testing (COMET)

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Hyaluronic acid (HA) is present in almost all biological fluids and tissues. The chemical HA structure is described as a linear polysaccharide with a high molecular mass (about one MDa) formed from disaccharide units containing Nacetyl-d-glucosamine and glucuronic acid. This chemical structure ensures an excellent biocompatibility. In addition its viscoelastic properties are singularly appreciated in cosmetic products like moisturizing preparations, anti-wrinkle effect cream (for the elasticity restoration) [1], and skin protection against ultraviolet irradiation [2]. HA is usually produced from non-sustainable resource, or from genetically modified (GMO) bacteria, or from animal waste [3]. A novel method production of this high value product (more than 100 k€/kg [4]) had recently emerged based on microalgae production process [5]. In order to be competitive, users of this new manufacturing method need to assess in-line the quality of the product and if it possible use this information for product quality optimization. Electromagnetic sensors are well known in the food industry for reliability and quick quality assessment of hydrocarbon based food like wheat [6].This paper reports some preliminary results on microalgae by product of an electromagnetic wideband radiofrequency sensor. This sensor consists of an open coaxial line cell filled with a liquid solution and impedance measurement of the cell is carried by an network analyzer at a temperature of 25°C. The microalgae studied where separated in two phases, a liquid one extracted directly from the reactor (MC) and a foam like extracted by an in-reactor skimmer (ME). In order to assess the sensibility of the measurement and simulate different production yield, extracted fraction MC and ME where diluted. These dilutions were carried with respectively microalgae nutriment solution (NS) and pure water in order to keep a constant ionic strength to achieve the low frequency conductivity constant and to avoid a measurement bias. The preliminary results show a good sensitivity of impedance vs HA microalgae concentration in the 1 MHz to 10 MHz range.

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“…Another soil core of each set was used with the Hydra Probe for determining ε' and ε" at 50 MHz and σ dc . Th e internal calculations for the Hydra Probe (Seyfried et al, 2005) are based on those of Campbell (1990), which are based on the impedance analysis of Kraft (1987), the same theory used for the VNA data. Th ese internal calculations were used to determine ε' and ε" at 50 MHz (without temperature correction) and σ dc .…”

Section: Hydra Probementioning

confidence: 99%

Hydra Probe and Twelve‐Wire Probe Comparisons in Fluids and Soil Cores

Logsdon

Green²,

Seyfried

et al. 2010

Soil Science Soc of Amer J

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All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Hydra Probe and Twelve-Wire Probe Comparisons in Fluids and Soil Cores Soil Physics A ccurate soil water content data are needed for evaluating the effi ciency of soil water use and for understanding soil water fl ow in the landscape. Automated soil water sensors infer the temporal dynamics of water content in the soil as part of the soil-plant-atmosphere continuum (McCoy et al., 2006). Many of these sensors are based on a relationship between permittivity and water content (θ). Th e assumption for using dielectric sensors to determine θ is based on known properties for free water, minerals, and air. Most sensors have a measurement frequency (f) in the megahertz to low gigahertz range, below the permittivity relaxation frequency (f rel) for free water (~17 GHz); therefore, the assumption is oft en made that the permittivity of pure water is relatively constant at the low-f value (76-80 depending on temperature). Permittivity is complex (ε*), with real (ε') and imaginary (ε") components. Th e ε" is aff ected by direct current electrical conductivity (σ dc) as well as a relaxation component (ε rel "), whereas ε' is only aff ected by a relaxation component:

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Constitutive parameter measurements of fluids and soil between 500 kHz and 5 MHz using a transmission line technique

Cited by 19 publications

References 12 publications

Short, Multineedle Frequency Domain Reflectometry Sensor Suitable for Measuring Soil Water Content

Short, Multineedle Frequency Domain Reflectometry Sensor Suitable for Measuring Soil Water Content

New wideband electromagnatic on-line system for microalgae production monitoring

Hydra Probe and Twelve‐Wire Probe Comparisons in Fluids and Soil Cores

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