Use of multi-length TDR data aimed to infer the dispersion law of nonmagnetic materials

This contribution presents a method of multi-length transmission lines, filled with or embedded in the material under test (MUT), based on time domain reflectometry (TDR), to measure the dispersion law of a nonmagnetic material. This approach is essential and can be exploited in both radiofrequency and microwave applications. The proposed technique expands on studies presented in [1-2], where dielectric, magnetic and conductive losses are accounted for by the complex relative permittivity and permeability of the MUT.Many materials of interest in geophysical [3-4] and biomedical [5-6] applications are non-magnetic but preliminary measurements with the proposed technique can help to determine if the MUT indeed has magnetic properties. Moreover, it is shown that establishing the non-magnetic nature of the MUT constitutes meaningful a-priori information that allows disambiguating experimental results, even with limited data in the frequency range of interest.Results relative to two different types of multi-length measurement data, namely data acquired by considering different lengths of a TDR probe entirely embedded in (or embedding) the MUT and data achieved from a sequential progressive embedding of the probe in the MUT (or, vice-versa, of the MUT in the probe) are presented to illustrate the method. The pros and cons of presented cases are also discussed. &#160;AcknowledgementsThis work is supported by the European Cost Action &#8220;Mywave&#8221; CA17115.References[1] R. Persico, M. Pieraccini, Measurement of dielectric and magnetic properties of Materials by means of a TDR probe, Near Surface Geophysics, vol. 16, n.2, pp.1-9, DOI:10.3997/1873-0604.2017046, 2018.[2] R. Persico, I. Farhat, L. Farrugia, S. d&#8217;Amico, C. Sammut, An innovative use of TDR probes: First numerical validations with a coaxial cable, Journal of Environmental & Engineering Geophysics, doi.org/10.2113/JEEG23.4.437, 23 (4): 437-442, 2018.[3] R. Pierri, G. Leone, F. Soldovieri, R. Persico, "Electromagnetic inversion for subsurface applications under the distorted Born approximation" Nuovo Cimento, vol. 24C, N. 2, pp 245-261, March-April 2001.[4] R. Persico, M. Ciminale, L. Matera, A new reconfigurable stepped frequency GPR system, possibilities and issues; applications to two different Cultural Heritage Resources, Near Surface Geophysics, vol. 12, n. 6, pp. 793-801 (doi: 10.3997/1873-0604.2014035), December 2014.[5] R. Pethig, "Dielectric Properties of Biological Materials: Biophysical and Medical Applications," in&#160;IEEE Transactions on Electrical Insulation, vol. EI-19, no. 5, pp. 453-474, Oct. 1984. doi: 10.1109/TEI.1984.298769&#160;[6] C. Gabriel,&#160;S. Gabriel&#160;and&#160;E Corthout, &#8220;The dielectric properties of biological tissues: I. Literature survey,&#8221; Physics in Medicine and Biology, vol. 41, no. 11, pp. 2231-2249, Nov. 1996.

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Multi-length TDR probes: future perspectives

10.5194/egusphere-egu21-15385 ◽

2021 ◽

Author(s):

Raffaele Persico ◽

Lourdes Farrugia ◽

Iman Farhat ◽

Charles Sammut

Keyword(s):

Magnetic Properties ◽

Early Stage ◽

Coaxial Cable ◽

Magnetic Characteristics ◽

Future Perspectives ◽

Near Surface ◽

Work Related ◽

Properties Of Materials ◽

Near Surface Geophysics ◽

Engineering Geophysics

In this contribution we will propose the use of multi-length TDR probes for measurements of the dielectric and possibly magnetic characteristics of a material under test (MUT) as a function of frequency. The multi-length strategy, consisting in making use of a TDR probe with adjustable length of the conductors, can allow the meaningful increase of information achievable about the MUT at each test frequency. We are still at an early stage about these possibilities, and many questions are still open at this time. However, some of our previous studies [1-3] show that the method is promising and can permit the acquisition of some information not intrinsically available from a traditional TDR probe, especially if the MUT shows a dispersive behaviour and possibly magnetic properties. In this contribution, we will discuss the recent work related in particular to geophysical applications.AcknowledgementsThis work in progress is being carried out within the European Cost Action CA17115 Mywave.References[1] R. Persico, M. Pieraccini, Measurement of dielectric and magnetic properties of Materials by means of a TDR probe, Near Surface Geophysics, vol. 16, n.2, pp.1-9, DOI:10.3997/1873-0604.2017046, 2018.[2] R. Persico, I. Farhat, L. Farrugia, S. d&#8217;Amico, C. Sammut, An innovative use of TDR probes: First numerical validations with a coaxial cable, Journal of Environmental & Engineering Geophysics, doi.org/10.2113/JEEG23.4.437, 23 (4): 437-442, 2018.[3] I. Farhat, L. Farrugia, R. Persico, S. D&#8217;Amico, and C. Sammut, Preliminary Experimental Measurements of the Dielectric and Magnetic Properties of a Material with a Coaxial TDR Probe in Re&#64258;ection Mode, Progress In Electromagnetics Research M, Vol. 91, 111&#8211;121, 2020.

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An Innovative Use of TDR Probes: First Numerical Validations with a Coaxial Cable

Journal of Environmental and Engineering Geophysics ◽

10.2113/jeeg23.4.437 ◽

2018 ◽

Vol 23 (4) ◽

pp. 437-442

Author(s):

Raffaele Persico ◽

Iman Farhat ◽

Lourdes Farrugia ◽

Sebastiano D'Amico ◽

Charles Sammut

Keyword(s):

Magnetic Properties ◽

Transmission Line ◽

Time Domain ◽

Numerical Data ◽

Time Domain Reflectometry ◽

Coaxial Cable ◽

Transmission Line Model ◽

Properties Of Materials

In this paper we propose a study regarding some possibilities that can be offered by a time domain reflectometry (TDR) probe in retrieving both dielectric and magnetic properties of materials. This technique can be of interest for several applications, among which the characterization of soil in some situations. In particular, here we propose an extension of the paper “Retrieving electric and magnetic propetries of the soil in situ: New possibilities”, presented at the IWAGPR, held in Edinburgh in 2017, and as a new contribution we will validate a transmission line model with numerical data simulated by the CST code.

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Remote Monitoring of Joints Status on In-Service High-Voltage Overhead Lines

Energies ◽

10.3390/en12061004 ◽

2019 ◽

Vol 12 (6) ◽

pp. 1004 ◽

Cited By ~ 1

Author(s):

Carlo Olivieri ◽

Francesco de Paulis ◽

Antonio Orlandi ◽

Giorgio Giannuzzi ◽

Roberto Salvati ◽

...

Keyword(s):

High Voltage ◽

Transmission Lines ◽

Remote Monitoring ◽

Power Transmission ◽

Measurement Data ◽

Time Domain Reflectometry ◽

Overhead Line ◽

Voltage Transformer ◽

Remote Monitoring System ◽

On Line

This work presents the feasibility study of an on-line monitoring technique aimed to discover unwanted variations of longitudinal impedance along the line (also named “impedance discontinuities”) and, possibly, incipient faults typically occurring on high voltage power transmission lines, like those generated by oxidated midspan joints or bolted joints usually present on such lines. In this paper, the focus is placed on the application and proper customization of a technique based on the time-domain reflectometry (TDR) technique when applied to an in-service high-voltage overhead line. An extensive set of numerical simulations are provided in order to highlight the critical points of this particular application scenario, especially those that concern the modeling of both the TDR signal injection strategy and the required high-voltage coupling devices, and to plan a measurement activity. The modeling and simulation approach followed for the study of either the overhead line or the on-line TDR system is fully detailed, discussing three main strategies. Furthermore, some measurement data that were used to characterize the specific coupling device selected for this application at high frequency—that is, a capacitive voltage transformer (CVT)—are presented and discussed too. This work sets the basic concepts underlying the implementation of an on-line remote monitoring system based on reflectometric principles for in-service lines, showing how much impact is introduced by the high-voltage coupling strategy on the amplitude of the detected reflected voltage waves (also named “voltage echoes”).

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Multi-length probes in GPR and TDR data

10.5194/egusphere-egu21-16499 ◽

2021 ◽

Author(s):

Raffaele Persico

Keyword(s):

Coaxial Cable ◽

Single Frequency ◽

Near Surface ◽

Radio Science ◽

Independent Information ◽

Electromagnetic Characteristics ◽

Stepped Frequency ◽

Near Surface Geophysics ◽

University Of Florence ◽

The Cost

I will expose some possibilities regarding the use of metallic probes of different lengths in GPR and TDR prospecting. With regard to GPR, multi-length probes are dipole-like antennas whose length can be changed by means of switches. The switches can be implemented with PIN diodes, and can act as electronic &#8220;knifes&#8221;. Therefore, they allow to cut (switched off) or prolong (switched on) the branches of a couple of antennas, and this allows to have more couples of equivalent antennas making use of a unique physical couple of antennas. This allows to contain the size of the system. In particular, a reconfigurable prototypal stepped frequency GPR system was developed within the project AITECH (http://www.aitechnet.com/ibam.html) and was tested in several cases histories &#160;[1-3]. Within this reconfigurable GPR, it is also possible to reconfigure vs. the frequency the integration times of the harmonic tones constituting the radiated signal. This feature allows to reject external electromagnetic interferences without filtering the spectrum of the received signal [4] and without increasing the radiated power.With regard to TDR measurements, a multi-length probe consists of a TDR device where the rods (in multi-wire version) or the length of internal and external conductor (in coaxial version) can be changed. This can be useful for the measurements of electromagnetic characteristics of a material under test (MUT), in particular its dielectric permittivity and magnetic permeability, both meant in general as complex quantities. Multi-length TDR measurements allow to acquire independent information on the MUT even at single frequency, and this can be of interest in the case of dispersive materials [5-6].AcknowledgementsI collaborated with several colleagues about the above issues. To list of them would be long, so I will just mention their affiliations: Florence Engineering srl, University of Florence, IDSGeoradar srl, 3d-radar Ltd, Institute for Archaeological and Monumental Heritage IBAM-CNR, University of Bari, University of Malta. Finally, a particular mention is deserved for the Cost Action TU1208.References[1] R. Persico, M. Ciminale, L. Matera, A new reconfigurable stepped frequency GPR system, possibilities and issues; applications to two different Cultural Heritage Resources, Near Surface Geophysics, 12, 793-801, 2014.[2] L. Matera, M. Noviello, M. Ciminale, R. Persico, Integration of multisensor data: an experiment in the archaeological park of Egnazia (Apulia, Southern Italy), Near Surface Geophysics, 13, 613-621, 2015.[3] R. Persico, S. D'Amico, L. Matera, E. Colica, C. De, Giorgio, A. Alescio, C. Sammut and P. Galea, P. (2019), GPR Investigations at St John's Co&#8208;Cathedral in Valletta, Near Surface Geophysics, 17, 213-229, 2019.[4] R. Persico, D. Dei, F. Parrini, L. Matera, Mitigation of narrow band interferences by means of a reconfigurable stepped frequency GPR system, Radio Science, 51, 2016.[5] R. Persico, M. Pieraccini, Measurement of dielectric and magnetic properties of Materials by means of a TDR probe, Near Surface Geophysics, 16,1-9, 2018.[6] R. Persico, I. Farhat, L. Farrugia, S. d&#8217;Amico, C. Sammut, An innovative use of TDR probes: First numerical validations with a coaxial cable, Journal of Environmental & Engineering Geophysics, 23, 437-442, 2018.&#160;

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Multi-length probes in GPR and TDR data

10.5194/egusphere-egu2020-7426 ◽

2020 ◽

Author(s):

Raffaele Persico

Keyword(s):

Coaxial Cable ◽

Single Frequency ◽

Near Surface ◽

Radio Science ◽

Independent Information ◽

Electromagnetic Characteristics ◽

Stepped Frequency ◽

Near Surface Geophysics ◽

University Of Florence ◽

The Cost

I will expose some possibilities regarding the use of metallic probes of different lengths in GPR and TDR prospecting. With regard to GPR, multi-length probes are dipole-like antennas whose length can be changed by means of switches. The switches can be implemented with PIN diodes, and can act as electronic &#8220;knifes&#8221;. Therefore, they allow to cut (switched off) or prolong (switched on) the branches of a couple of antennas, and this allows to have more couples of equivalent antennas making use of a unique physical couple of antennas. This allows to contain the size of the system. In particular, a reconfigurable prototypal stepped frequency GPR system was developed within the project AITECH (http://www.aitechnet.com/ibam.html) &#160;and was tested in several cases histories &#160;[1-3]. Within this reconfigurable GPR, it is also possible to reconfigure vs. the frequency the integration times of the harmonic tones constituting the radiated signal. This feature allows to reject external electromagnetic interferences without filtering the spectrum of the received signal [4] and without increasing the radiated power.With regard to TDR measurements, a multi-length probe consists of a TDR device where the rods (in multi-wire version) or the length of internal and external conductor (in coaxial version) can be changed. This can be useful for the measurements of electromagnetic characteristics of a material under test (MUT), in particular its dielectric permittivity and magnetic permeability, both meant in general as complex quantities. Multi-length TDR measurements allow to acquire independent information on the MUT even at single frequency, and this can be of interest in the case of dispersive materials [5-6].AcknowledgementsI collaborated with several colleagues about the above issues. To list of them would be long, so I will just mention their affiliations: Florence Engineering srl, University of Florence, IDSGeoradar srl, 3d-radar Ltd, Institute for Archaeological and Monumental Heritage IBAM-CNR, University of Bari, University of Malta. Finally, a particular mention is deserved for the Cost Action TU1208.References[1] R. Persico, M. Ciminale, L. Matera, A new reconfigurable stepped frequency GPR system, possibilities and issues; applications to two different Cultural Heritage Resources, Near Surface Geophysics, 12, 793-801, 2014.[2] L. Matera, M. Noviello, M. Ciminale, R. Persico, Integration of multisensor data: an experiment in the archaeological park of Egnazia (Apulia, Southern Italy), Near Surface Geophysics, 13, 613-621, 2015.[3] R. Persico, S. D'Amico, L. Matera, E. Colica, C. De, Giorgio, A. Alescio, C. Sammut and P. Galea, P. (2019), GPR Investigations at St John's Co&#8208;Cathedral in Valletta, Near Surface Geophysics, 17, 213-229, 2019.[4] R. Persico, D. Dei, F. Parrini, L. Matera, Mitigation of narrow band interferences by means of a reconfigurable stepped frequency GPR system, Radio Science, 51, 2016.[5] R. Persico, M. Pieraccini, Measurement of dielectric and magnetic properties of Materials by means of a TDR probe, Near Surface Geophysics, 16,1-9, 2018.[6] R. Persico, I. Farhat, L. Farrugia, S. d&#8217;Amico, C. Sammut, An innovative use of TDR probes: First numerical validations with a coaxial cable, Journal of Environmental & Engineering Geophysics, 23, 437-442, 2018.

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