Comparison of the different reconstruction techniques of permittivity from S-parameters

Gorriti, A.G.; Slob, Evert

doi:10.1109/tgrs.2005.854312

Cited by 22 publications

(12 citation statements)

References 13 publications

(35 reference statements)

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“…Figure 1 shows a coaxial measuring cell. To measure the complex dielectric constant in the 10 MHz-8 GHz frequency range, a coaxial line measurement method was used which was successfully used to measure the dielectric properties of liquids and bulk materials [4,5]. This method is based on measuring the transmission and reflection coefficients of a section of a coaxial line.…”

Section: Measurement Of the Permittivity Of A Biological Mediummentioning

confidence: 99%

Radio-Wave Tomography of Inhomogeneities in Biological Media with Multi-Frequency Sounding in the Range 2-8 GHZ

et al. 2018

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Abstract. In this paper, a method for detecting and mapping inhomogeneities in biological tissues using the radio-wave tomosynthesis method is presented. The proposed method of radio-wave tomosynthesis allows us to calculate the three-dimensional distribution of the permittivity of the space under study and, thereby, to detect tissue inhomogeneities and to determine their location and size. Due to their harmlessness for humans, these methods are suitable for dynamic observation of changes in the size of formation, in contrast to x-ray methods, for which regular doses of ionizing radiation are contraindicated. Therefore, the development of non-invasive methods for the search for inhomogeneities in biological media based on radio-wave sounding, which makes it possible to identify pathological formations, is now very relevant.

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Section: Measurement Of the Permittivity Of A Biological Mediummentioning

confidence: 99%

Radio-Wave Tomography of Inhomogeneities in Biological Media with Multi-Frequency Sounding in the Range 2-8 GHZ

et al. 2018

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“…With this designed feature, the major advantage of the CT cell is its possibility to core a soil sample in situ or in laboratory experiments [235]. Generally, in the case of transverse EM mode propagation in non-magnetic materials, the ε ⋆ r,eff can be described by the following set of equations [140,215,226,236,237]:…”

Section: Ct Measurement Techniquesmentioning

confidence: 99%

“…• the Nicolson-Ross-Weir (NRW) algorithm [237,238] • the modified NRW algorithm (BJ) [239,240] • the propagation matrix (PM) method [236,241,242] • the iterative method (BJI) [180,243].…”

Section: Ct Measurement Techniquesmentioning

confidence: 99%

“…A further quasi-analytical approach is the PM method, which is based on the propagation matrix A, B and C. As shown in Figure 5.4B, A and C (withÂ = C,Ĉ = A; [236,244]) refer to the sections between reference Planes 1 and 2, which include the adapter units. The matrix [236,244]) describes the section with the MUT between reference Planes 2-2.…”

Section: Ct Measurement Techniquesmentioning

confidence: 99%

“…The matrix [236,244]) describes the section with the MUT between reference Planes 2-2. The appropriate formulation of the propagation matrices is given by two equations:…”

Section: Ct Measurement Techniquesmentioning

confidence: 99%

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Mechanical, hydraulic, and dielectric characterisation of fine-grained soils during densification

Schwing¹

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Soil characterisation is of primary interest for several disciplines, including geotechnical and geo-environmental engineering, soil science, and agriculture. An upcoming and promising method for soil characterisation relies on the high-frequency electromagnetic measurement technique which provides the potential to explore and investigate soils. However, successful application of this technique requires a profound understanding of the multi-physical processes arising from interactions between soil as a porous medium and the propagation of electromagnetic waves. This thesis focuses on a coupled experimental investigation of the mechanical, hydraulic, and dielectric characterisation of fine-grained soil during densification.In the framework of this thesis, the following steps have been completed and novel findings have been made:1. Probe designs have been developed, modified and improved to measure the dielectric soil properties in a frequency range from 1 MHz to 3 GHz during shrinkage and compaction. A low-cost in-house-manufactured probe was introduced, which was specifically designed for standardised geotechnical soil shrinkage test. During preliminary investigations, the calibration procedure and performance of these sensors were experimentally and numerically tested. The results showed agreement in the targeted frequency window.2. Compaction and shrinkage tests on fine-grained soils were conducted in combination with dielectric and soil suction measurements. The shrinkage curve and soil water characteristic curve (SWCC) was established and successfully parameterised with physical based models. The complex permittivity was determined in a frequency range from 1 MHz to 3 GHz. The dielectric properties measured during the shrinkage test showed a sudden drop of complex permittivity which could be located in the residual shrinkage zone.3. A theoretical electromagnetic mixture approach was used to model the measured frequency dependent dielectric properties of soils during shrinkage and compaction based on the parameterised shrinkage curve and SWCC. The theoretical results were compared to the dielectric measurements on different fine-grained soils. The comparison ii showed that the real part of permittivity could be well predicted whereas the imaginary part suffered inaccuracies.4. A sensitivity analysis was performed with the theoretical electromagnetic mixture approach in consideration of the shrinkage behaviour and SWCC in order to investigate the influence of soil suction and dry density on the frequency dependent permittivity.The sensitivity analysis showed that the real part of the permittivity near 1 GHz was insensitive to changes in the soil suction and dry density. In the MHz range, the real part of the permittivity was more sensitive to changes in soil suction than it was to dry density. The imaginary part of the permittivity was generally observed to be more sensitive to soil suction over the entire frequency range.

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Dielectric relaxation behavior of Callovo‐Oxfordian clay rock: A hydraulic‐mechanical‐electromagnetic coupling approach

Wagner

Boré²,

Robinet³

et al. 2013

JGR Solid Earth

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[1] Water content is a key parameter to monitor in nuclear waste repositories such as the planed underground repository in Bure, France, in the Callovo-Oxfordian (COx) clay formation. High-frequency electromagnetic (HF-EM) measurement techniques, i.e., time or frequency domain reflectometry, offer useful tools for quantitative estimation of water content in porous media. However, despite the efficiency of HF-EM methods, the relationship between water content and dielectric material properties needs to be characterized. Moreover, the high amount of swelling clay in the COx clay leads to dielectric relaxation effects which induce strong dispersion coupled with high absorption of EM waves. Against this background, the dielectric relaxation behavior of the clay rock was studied at frequencies from 1 MHz to 10 GHz with network analyzer technique in combination with coaxial transmission line cells. For this purpose, undisturbed and disturbed clay rock samples were conditioned to achieve a water saturation range from 0.16 to nearly saturation. The relaxation behavior was quantified based on a generalized fractional relaxation model under consideration of an apparent direct current conductivity assuming three relaxation processes: a high-frequency water process and two interface processes which are related to interactions between the aqueous pore solution and mineral particles (adsorbed/hydrated water relaxation, counter ion relaxation and Maxwell-Wagner effects). The frequency-dependent HF-EM properties were further modeled based on a novel hydraulic-mechanical-electromagnetic coupling approach developed for soils. The results show the potential of HF-EM techniques for quantitative monitoring of the hydraulic state in underground repositories in clay formations.

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Comparison of the different reconstruction techniques of permittivity from S-parameters

Cited by 22 publications

References 13 publications

Radio-Wave Tomography of Inhomogeneities in Biological Media with Multi-Frequency Sounding in the Range 2-8 GHZ

Radio-Wave Tomography of Inhomogeneities in Biological Media with Multi-Frequency Sounding in the Range 2-8 GHZ

Mechanical, hydraulic, and dielectric characterisation of fine-grained soils during densification

Dielectric relaxation behavior of Callovo‐Oxfordian clay rock: A hydraulic‐mechanical‐electromagnetic coupling approach

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