scholarly journals Dielectric Properties of Glass Beads with Talc as a Reference Material for Calibration and Verification of Dielectric Methods and Devices for Measuring Soil Moisture

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1968 ◽  
Author(s):  
Justyna Szerement ◽  
Hironobu Saito ◽  
Kahori Furuhata ◽  
Shin Yagihara ◽  
Agnieszka Szypłowska ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Reference Material ◽  
Dielectric Permittivity ◽  
Open Water ◽  
Glass Beads ◽  
Vector Network Analyzer ◽  
Network Analyzer ◽  
Calibration Curves ◽  
Salinity Index ◽  
Calibration And Verification

This paper presents dielectric measurements of talc, glass beads, and their mixtures under different moisture and salinity levels. The measurements were conducted using a prototype seven-rod probe (15 mm long central rod) connected to a single port of vector network analyzer. The samples were moistened with distilled water and KCl solutions in order to obtain six different moisture content levels. The complex dielectric permittivity was determined from vector network analyzer reflection-coefficient measurements based on the open-water-liquid calibration procedure. Next, the fitting of volumetric water content–real part of dielectric permittivity calibration curves was performed for each material at selected frequencies, and the obtained relations were compared with well-known calibration equations. Additionally, a salinity index for the tested materials was calculated. It was concluded that pure talc is not an optimal material for the calibration and verification of dielectric methods. The calibration curves obtained for glass beads and the mixtures of glass beads with talc gave results close to well-known reference calibration functions. Additionally, the addition of talc caused the data points to be less scattered. Moreover, the values of the salinity index for the tested materials were in a good agreement with literature data for sand. The obtained results indicated that glass beads with the addition of talc can be used as a reference material for the calibration and verification of dielectric methods and devices for soil moisture measurement.

Combined vector network analyzer and impedance analyzer for broadband determination of complex permittivity spectrum of glass beads with talc

2020 ◽  
Author(s):  
Justyna Szerement ◽  
Hironobu Saito ◽  
Kahori Furuhata ◽  
Shin Yagihara ◽  
Agnieszka Szypłowska ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Soil Moisture ◽  
Dielectric Permittivity ◽  
Glass Beads ◽  
Vector Network Analyzer ◽  
Complex Dielectric Permittivity ◽  
Network Analyzer ◽  
Frequency Range ◽  
Impedance Analyzer ◽  
Permittivity Spectrum

<p>Soil complex dielectric permittivity is frequency dependent. At low frequencies soil dielectric spectrum exhibits relaxation effects mainly due to interfacial phenomena caused by water strongly bounded to solid phase particles surfaces, double-layer effects and Maxwell-Wagner effect. At frequencies of several GHz and above, the influence of dielectric dispersion of free water dipoles can be observed.  Since dielectric soil moisture meters operate at frequencies from kHz up to several GHz, their output can be affected by these phenomena.</p><p>Currently, there is a variety of commercial sensors that operate at various frequencies from kHz up to several GHz. Most popular are TDR sensors with frequency band up to 1-2 GHz and capacitance/impedance sensors that operate at a single frequency usually from the range <br>1-150 MHz. Therefore, the knowledge of the broadband complex dielectric permittivity spectrum can help to improve the existing and develop new methods and devices for soil moisture and salinity estimation. Also, accurate characterization of complex dielectric permittivity spectrum of porous materials in the broadband frequency range is required for modeling of dielectric properties of materials in terms of moisture, salinity, density, mineralogy etc.</p><p>The aim of the study was to measure the complex dielectric permittivity of glass beads with 5% talc moistened with distilled water and saline water (electrical conductivity of 500, 1000, 1500 mS/m). The experiment was carried out using a seven-rod probe connected to an impedance analyzer (IA) and a vector network analyzer (VNA) using a multiplexer in the frequency range from 40Hz to 110MHz (IA) and 10MHz to 500MHz (VNA). The glass beads (90-106 µm, Fuji Manufacturing Industries, Japan) with 5% talc (Sigma Aldrich) in 4 different moisture and 4 different salinity values were examined. The results obtained from the IA and the VNA were combined and modeled with complex conductivity and dielectric permittivity model. The influence of water content and electrical conductivity on broadband complex dielectric spectra and the fitted model parameters was examined.</p><p> </p><p>The work has been supported by the National Centre for Research and Development, Poland, BIOSTRATEG3/343547/8/NCBR/2017.</p>

Complex Dielectric Permittivity of Sandy Loam as a Function of Salinity and Biomass at Microwaves

2013 ◽  
Vol 209 ◽  
pp. 116-120 ◽  
Author(s):  
Arun Sharma ◽  
K.C. Pancholi ◽  
S.P. Bhatnagar
Keyword(s):  
Soil Moisture ◽  
Dielectric Permittivity ◽  
Sandy Loam ◽  
Strong Dependence ◽  
Normal Incidence ◽  
Complex Dielectric Permittivity ◽  
Network Analyzer ◽  
Frequency Range ◽  
Moisture Contents ◽  
Loam Soil

Real and Imaginary parts of Complex Dielectric Permittivity (ε’ and ε” ) of Sandy Loam soil have been measured in the frequency range 150 MHz – 2.4 GHz using a Vector Network Analyzer at varied Moisture contents, Salinity and Biomass. The Emissivity of the soil for normal incidence was also calculated from measured values of Complex Permittivity. The measured permittivity data show strong dependence on moisture content. Salinity causes higher permittivity and dielectric loss. Biomass appears to enhance the permittivity data due to increase in porosity of the soil. The emissivity of the soil was observed to decrease with increasing soil moisture and soil salinity, but it increases with biomass.

scholarly journals Electromagnetic characteristics of materials based on ultrafine hexaferrite powders

2021 ◽  
Vol 1198 (1) ◽  
pp. 012005
Author(s):  
YuN Gladkov ◽  
AS Kachalov ◽  
EYu Korovyn ◽  
AA Pavlova
Keyword(s):  
Composite Materials ◽  
Dielectric Permittivity ◽  
Frequency Dependence ◽  
Mechanical Treatment ◽  
Wide Band ◽  
Vector Network Analyzer ◽  
Network Analyzer ◽  
Frequency Range ◽  
Nanosized Powders ◽  
Electromagnetic Characteristics

Abstract The electromagnetic characteristics of composite materials based on nanosized powders of W-type hexaferrites are considered in the article. It is shown that not only the composition, but also the mechanical treatment affects the electromagnetic parameters. This article presents the frequency dependence of the complex magnetic and dielectric permittivity of a system of W-type hexafferites. The studies were carried out on a universal wide-band measuring complex based on the Agilent PNA-X N4257A Vector Network Analyzer. The results are presented in the frequency range from 2 to 14 GHz.

Reconfigurable SDM Optical Vector Network Analyzer

2014 ◽  
Author(s):  
Joel Carpenter ◽  
Benjamin J. Eggleton ◽  
Jochen Schröder
Keyword(s):  
Vector Network Analyzer ◽  
Network Analyzer

scholarly journals Wideband Active Load–Pull by Device Output Match Compensation Using a Vector Network Analyzer

2021 ◽  
Vol 69 (1) ◽  
pp. 874-886
Author(s):  
Alberto Maria Angelotti ◽  
Gian Piero Gibiino ◽  
Troels S. Nielsen ◽  
Dominique Schreurs ◽  
Alberto Santarelli
Keyword(s):  
Vector Network Analyzer ◽  
Network Analyzer ◽  
Active Load ◽  
Load Pull

scholarly journals Simulation and Experimental Study of the Near Field Probe in the Form of a Folded Dipole for Measuring Glucose Concentration

2021 ◽  
Vol 11 (12) ◽  
pp. 5415
Author(s):  
Aleksandr Gorst ◽  
Kseniya Zavyalova ◽  
Aleksandr Mironchev ◽  
Andrey Zapasnoy ◽  
Andrey Klokov
Keyword(s):  
Experimental Measurement ◽  
Glucose Concentration ◽  
Field Experiments ◽  
Near Field ◽  
Vector Network Analyzer ◽  
Human Hand ◽  
Physical Parameters ◽  
Network Analyzer ◽  
Frequency Range ◽  
Average Deviation

The article investigates the near-field probe of a special design to account for changes in glucose concentration. The probe is designed in such a way that it emits radiation in both directions from its plane. In this paper, it was proposed to modernize this design and consider the unidirectional emission of the probe in order to maximize the signal and reduce energy loss. We have done extensive research for both bidirectional and unidirectional probe designs. Numerical simulations and field experiments were carried out to determine different concentrations of glucose (0, 4, 5.3, 7.5 mmol/L). Numerical modeling of a unidirectional probe showed that the interaction of radiation generated by such a probe with a multilayer structure simulating a human hand showed a better result and high sensitivity compared to a bidirectional probe. Further, based on the simulation results, a phantom (physical model) of a human hand was recreated from layers with dielectric properties as close as possible to the properties of materials during simulation. The probe was constructed from a copper tube and matched both the geometric and physical parameters of the model. The experimental measurement was carried out using a vector network analyzer in the frequency range 2–10 GHz. The experimental measurement was carried out using a vector network analyzer in the frequency range 2–10 GHz for the unidirectional and bidirectional probes. Further, the results of the experiment were compared with the results of numerical simulation. According to the results of multiple experiments, it was found that the average deviation between the concentrations was 2 dB for a unidirectional probe and 0.4 dB for a bidirectional probe. Thus, the sensitivity of the unidirectional probe was 1.5 dB/(mmol/L) for the bidirectional one 0.3 dB/(mmol/L). Thus, the improved design of the near-field probe can be used to record glucose concentrations.

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