scholarly journals Dielectric characterization of vegetation at L band using an open-ended coaxial probe

2018 ◽  
Vol 7 (3) ◽  
pp. 195-208 ◽  
Author(s):  
Alex Mavrovic ◽  
Alexandre Roy ◽  
Alain Royer ◽  
Bilal Filali ◽  
François Boone ◽  
...  
Keyword(s):  
Black Spruce ◽  
Microwave Remote Sensing ◽  
Dielectric Characterization ◽  
Sensing Applications ◽  
Remote Sensing Applications ◽  
L Band ◽  
Permittivity Measurements ◽  
Coaxial Probe

Abstract. Decoupling the integrated microwave signal originating from soil and vegetation remains a challenge for all microwave remote sensing applications. To improve satellite and airborne microwave data products in forest environments, a precise and reliable estimation of the relative permittivity (ε=ε′-iε′′) of trees is required. We developed an open-ended coaxial probe suitable for in situ permittivity measurements of tree trunks at L-band frequencies (1–2 GHz). The probe is characterized by uncertainty ratios under 3.3 % for a broad range of relative permittivities (unitless), [2–40] for ε′ and [0.1–20] for ε′′. We quantified the complex number describing the permittivity of seven different tree species in both frozen and thawed states: black spruce, larch, red spruce, balsam fir, red pine, aspen and black cherry. Permittivity variability is substantial and can range up to 300 % for certain species. Our results show that the permittivity of wood is linked to the freeze–thaw state of vegetation and that even short winter thaw events can lead to an increase in vegetation permittivity. The open-ended coaxial probe proved to be precise enough to capture the diurnal cycle of water storage inside the trunk for the length of the growing season.

scholarly journals Dielectric characterization of vegetation at L-band using an open-ended coaxial probe

2018 ◽  
Author(s):  
Alex Mavrovic ◽  
Alexandre Roy ◽  
Alain Royer ◽  
Filali Bilal ◽  
François Boone ◽  
...  
Keyword(s):  
Black Spruce ◽  
Microwave Remote Sensing ◽  
Dielectric Characterization ◽  
Sensing Applications ◽  
Remote Sensing Applications ◽  
L Band ◽  
Permittivity Measurements ◽  
Coaxial Probe

Abstract. Decoupling the integrated microwave signal originating from soil and vegetation remains a challenge for all microwave remote sensing applications. To improve satellite and airborne microwave data products in forest environments, a precise and reliable estimation of the relative permittivity (𝜺 = 𝜺’ – i 𝜺’’) of the trees is required. We developed an open-ended coaxial probe suitable for in situ permittivity measurements of tree trunks at L-band wavelengths (1–2 GHz). The probe is characterized by uncertainties under 3.3 % for a broad range of permittivities, [2–40] for 𝜺’ and [0.1–20] for 𝜺’’. We quantified the complex number describing the permittivity of seven different tree species in both frozen and thawed states: black spruce, larch, red spruce, balsam fir, red pine, aspen and black cherry. Variability in permittivity is substantial, and can range up to 300 % for some species. Our results show that the permittivity of wood is linked to the freeze/thaw state of the vegetation and that even short winter thaw events lead to an increase in vegetation permittivity. The open-ended coaxial probe proved to be precise enough to capture the diurnal cycle of water storage inside the trunk over the growing season.

X-ray diffraction and infrared characterization of Oxisols from central and southeastern Brazil

Clay Minerals ◽  
2008 ◽  
Vol 43 (4) ◽  
pp. 549-560 ◽  
Author(s):  
R. P. Nitzsche ◽  
J. B. Percival ◽  
J. K. Torrance ◽  
J. A. R. Stirling ◽  
J. T. Bowen
Keyword(s):  
Remote Sensing ◽  
Near Infrared ◽  
Microwave Remote Sensing ◽  
Short Wave ◽  
Southeastern Brazil ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sensing Applications ◽  
Remote Sensing Applications

AbstractEleven Oxisols with high clay contents, 2.6–59.7 wt.% Fe2O3, and containing hematite, goethite, magnetite and maghemite, from São Paulo, Minas Gerais and Goiás, Brazil, were studied for the purpose of microwave remote sensing applications in the 0.3 to 300 GHz range. Of special interest are: the pseudosand effect caused by Fe-oxide cementation of clusters of soil particles; the mineralogy; and whether the soil magnetic susceptibility affected by ferromagnetic magnetite and maghemite interferes with microwave propagation. Quantitative mineralogical analyses were conducted using X-ray diffraction with Rietveld refinement. Visible, near infrared and short wave infrared spectroscopic analyses were used to characterize the samples qualitatively for comparison with published spectral radiometry results. Quartz (3–88%), hematite (2–36%) and gibbsite (1–40%) occurred in all soils, whereas kaolinite (2–70%) and anatase (2–13%) occurred in nine samples. Ilmenite (1–8%) was found in eight soils and goethite (2–39%) in seven. Of the ferromagnetic minerals, maghemite occurred in seven soils (1–13%) and three contained magnetite (<2%). These results will be applied to the interpretation of the effect of Fe oxides, particularly the ferromagnetic oxides, on microwave interaction with high-Fe soils, with ultimate application to the monitoring of soil water content by microwave remote sensing.

Supplementary material to "Dielectric characterization of vegetation at L-band using an open-ended coaxial probe"

2018 ◽  
Author(s):  
Alex Mavrovic ◽  
Alexandre Roy ◽  
Alain Royer ◽  
Filali Bilal ◽  
François Boone ◽  
...  
Keyword(s):  
Dielectric Characterization ◽  
Supplementary Material ◽  
L Band ◽  
Coaxial Probe

scholarly journals Soil dielectric characterization at L-band microwave frequencies during freeze-thaw transitions

2020 ◽  
Author(s):  
Alex Mavrovic ◽  
Renato Pardo Lara ◽  
Aaron Berg ◽  
François Demontoux ◽  
Alain Royer ◽  
...  
Keyword(s):  
Current Model ◽  
Freezing And Thawing ◽  
Microwave Frequencies ◽  
Dielectric Characterization ◽  
Freeze Thaw ◽  
L Band ◽  
Satellite Microwave ◽  
Permittivity Measurements ◽  
Microwave Permittivity

Abstract. Soil microwave permittivity is a crucial parameter in passive microwave retrieval algorithms but remains a challenging variable to measure. To validate and improve satellite microwave data products, precise and reliable estimations of the relative permittivity (ɛr = ɛ / ɛ0 = ɛ’ - jɛ’’; unitless) of soils are required, particularly for frozen soils. In this study, permittivity measurements were acquired using two different instruments: the newly designed open-ended coaxial probe (OECP) and the conventional Stevens HydraProbe. Both instruments were used to characterize the permittivity of soil samples undergoing several freeze/thaw cycles in a laboratory environment. The measurements were compared to soil permittivity models. We show that the OECP is a suitable device for measuring frozen (ɛ’frozen = [3.5;6.0], ɛ’’frozen = [0.4;1.2]) and thawed (ɛ’thawed = [6.5;22.8], ɛ’’thawed = [1.4;5.7]) soil microwave permittivity. We also demonstrate that cheaper and widespread soil permittivity probes operating at lower frequencies (i.e. Stevens HydraProbe) can be used to estimate microwave permittivity given proper calibration relative to an L-band (1–2 GHz) probe. This study also highlighted the need to improve dielectric soil models, particularly during freeze/thaw transitions. There are still important discrepancies between in situ and modelled estimates and no current model accounts for the hysteresis effect shown between freezing and thawing processes which could have a significant impact on freeze/thaw detection from satellites.

scholarly journals Soil dielectric characterization during freeze–thaw transitions using L-band coaxial and soil moisture probes

2021 ◽  
Vol 25 (3) ◽  
pp. 1117-1131
Author(s):  
Alex Mavrovic ◽  
Renato Pardo Lara ◽  
Aaron Berg ◽  
François Demontoux ◽  
Alain Royer ◽  
...  
Keyword(s):  
Current Model ◽  
Freezing And Thawing ◽  
Dielectric Characterization ◽  
Freeze Thaw ◽  
Thawing Processes ◽  
L Band ◽  
Satellite Microwave ◽  
Permittivity Measurements ◽  
Microwave Permittivity

Abstract. Soil microwave permittivity is a crucial parameter in passive microwave retrieval algorithms but remains a challenging variable to measure. To validate and improve satellite microwave data products, precise and reliable estimations of the relative permittivity (εr=ε/ε0=ε′-jε′′; unitless) of soils are required, particularly for frozen soils. In this study, permittivity measurements were acquired using two different instruments: the newly designed open-ended coaxial probe (OECP) and the conventional Stevens HydraProbe. Both instruments were used to characterize the permittivity of soil samples undergoing several freeze–thaw cycles in a laboratory environment. The measurements were compared to soil permittivity models. The OECP measured frozen (εfrozen′=[3.5; 6.0], εfrozen′′=[0.46; 1.2]) and thawed (εthawed′=[6.5; 22.8], εthawed′′=[1.43; 5.7]) soil microwave permittivity. We also demonstrate that cheaper and widespread soil permittivity probes operating at lower frequencies (i.e., Stevens HydraProbe) can be used to estimate microwave permittivity given proper calibration relative to an L-band (1–2 GHz) probe. This study also highlighted the need to improve dielectric soil models, particularly during freeze–thaw transitions. There are still important discrepancies between in situ and modeled estimates and no current model accounts for the hysteresis effect shown between freezing and thawing processes, which could have a significant impact on freeze–thaw detection from satellites.

scholarly journals In Situ Dielectric Characterization of Poly(ethylene oxide) Melts Containing Lithium Perchlorate under Steady Shear Flow

2004 ◽  
Vol 37 (18) ◽  
pp. 7064-7064
Author(s):  
Yumi Matsumiya ◽  
Nitash P. Balsara ◽  
John B. Kerr ◽  
Tadashi Inoue ◽  
Hiroshi Watanabe
Keyword(s):  
Shear Flow ◽  
Ethylene Oxide ◽  
Lithium Perchlorate ◽  
Dielectric Characterization ◽  
Steady Shear Flow ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Oxide Melts

Non-intrusive in-situ permittivity measurements dedicated to the development of a P and L band dielectric model of wood

2021 ◽  
Author(s):  
F. Demontoux ◽  
M. Gati ◽  
M. el Boudali ◽  
L. Villard ◽  
JP Wigneron ◽  
...  
Keyword(s):  
Dielectric Model ◽  
L Band ◽  
Permittivity Measurements

scholarly journals A Novel Cesaro Fractal EBG-based Sensing Platform for Dielectric Characterization of Liquids

2020 ◽  
Author(s):  
Muhammad Zubair ◽  
Muhammad Qasim Mehmood ◽  
Kashif Riaz ◽  
Amna Zubair ◽  
Ali Arif
Keyword(s):  
Cost Effective ◽  
Good Precision ◽  
Dielectric Characterization ◽  
Sensing Applications ◽  
Sensing Platform ◽  
Dielectric Constant And Loss ◽  
Increased Sensitivity ◽  
Rms Error ◽  
Measured Sensitivity

<p>This paper presents a compact, cost-effective, and contactless fractal modified EBG-based microwave sensing platform for dielectric characterization of liquids by analyzing the variation in the reflection coefficient of an antenna. The reported design is composed of a triangular-shaped antenna (0.323λ­<sub>o </sub>x 0.323λ­<sub>o</sub>) placed over a 3 x 3 array of Cesaro fractal based EBG plane (0.7λ­<sub>o</sub> x 0.7λ­<sub>o</sub>) operating at 2.45 GHz. A significant enhancement of the E-field in the sensing region has been achieved with the incorporation of Cesaro fractals in the EBG plane which results in increased sensitivity and compactness. To validate its performance, absolute solutions of butan-1-ol, methanol, and water are loaded, and a maximum measured sensitivity of 0.875% and a maximum quality factor of 90.05 is achieved. Moreover, a maximum RMS error in retrieved values of dielectric constant and loss tangent of liquid under test is found to be 1.092% and 0.813%, respectively. Our demonstrated EBG-based sensor has a compact footprint with good precision, affordability, and ease of operation in detecting liquids for microwave sensing applications. </p><p><br></p>

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