Wideband Characterization of Soil Complex Dielectric Permittivity Spectrum

Author(s):  
Agnieszka Szyplowska ◽  
Hironobu Saito ◽  
Shin Yagihara ◽  
Minoru Fukuzaki ◽  
Kahori Furuhata ◽  
...  
2019 ◽  
Vol 574 ◽  
pp. 517-528 ◽  
Author(s):  
Agnieszka Szypłowska ◽  
Justyna Szerement ◽  
Arkadiusz Lewandowski ◽  
Marcin Kafarski ◽  
Andrzej Wilczek ◽  
...  

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1646 ◽  
Author(s):  
Justyna Szerement ◽  
Aleksandra Woszczyk ◽  
Agnieszka Szypłowska ◽  
Marcin Kafarski ◽  
Arkadiusz Lewandowski ◽  
...  

This paper presents a novel seven-rod sensor used for time-domain reflectometry (TDR) and frequency-domain reflectometry (FDR) measurements of soil water content in a well-defined sample volume. The probe directly measures the complex dielectric permittivity spectrum and for this purpose requires three calibration media: air, water, and ethanol. Firstly, electromagnetic simulations were used to study the influence of the diameter of a container on the sensitivity zone of the probe with respect to the measured calibration media and isopropanol as a verification liquid. Next, the probe was tested in three soils—sandy loam and two silt loams—with six water contents from air-dry to saturation. The conversion from S 11 parameters to complex dielectric permittivity from vector network analyzer (VNA) measurements was obtained using an open-ended liquid procedure. The simulation and measurement results for the real part of the isopropanol dielectric permittivity obtained from four containers with different diameters were in good agreement with literature data up to 200 MHz. The real part of the dielectric permittivity was extracted and related to the moisture of the tested soil samples. Relations between the volumetric water content and the real part of the dielectric permittivity (by FDR) and apparent dielectric permittivity (by TDR) were compared with Topp’s equation. It was concluded that the best fit to Topp’s equation was observed in the case of a sandy loam. Data calculated according to the equation proposed by Malicki, Plagge, and Roth gave results closer to Topp’s calibration. The obtained results indicated that the seven-rod probe can be used to accurately measure of the dielectric permittivity spectrum in a well-defined sample volume of about 8 cm3 in the frequency range from 20 MHz to 200 MHz.


2020 ◽  
Author(s):  
Justyna Szerement ◽  
Hironobu Saito ◽  
Kahori Furuhata ◽  
Shin Yagihara ◽  
Agnieszka Szypłowska ◽  
...  

<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>


2016 ◽  
Vol 15 (3) ◽  
pp. vzj2015.10.0135 ◽  
Author(s):  
Agnieszka Szypłowska ◽  
Andrzej Wilczek ◽  
Marcin Kafarski ◽  
Wojciech Skierucha

Author(s):  
Sema Türkay ◽  
Adem Tataroğlu

AbstractRF magnetron sputtering was used to grow silicon nitride (Si3N4) thin film on GaAs substrate to form metal–oxide–semiconductor (MOS) capacitor. Complex dielectric permittivity (ε*), complex electric modulus (M*) and complex electrical conductivity (σ*) of the prepared Au/Si3N4/p-GaAs (MOS) capacitor were studied in detail. These parameters were calculated using admittance measurements performed in the range of 150 K-350 K and 50 kHz-1 MHz. It is found that the dielectric constant (ε′) and dielectric loss (ε″) value decrease with increasing frequency. However, as the temperature increases, the ε′ and ε″ increased. Ac conductivity (σac) was increased with increasing both temperature and frequency. The activation energy (Ea) was determined by Arrhenius equation. Besides, the frequency dependence of σac was analyzed by Jonscher’s universal power law (σac = Aωs). Thus, the value of the frequency exponent (s) were determined.


2016 ◽  
Vol 52 ◽  
pp. 161-167 ◽  
Author(s):  
Igor V. Kotelnikov ◽  
Andrey G. Altynnikov ◽  
Anatoly Konstantinovich Mikhailov ◽  
Valentina V. Medvedeva ◽  
Andrey Kozyrev

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