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

Mavrovic, Alex; Roy, Alexandre; Royer, A.; Filali, Bilal; Boone, F.R.; Pappas, Christoforos; Sonnentag, Oliver

doi:10.5194/gi-7-195-2018

Cited by 29 publications

(17 citation statements)

References 62 publications

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“…The measurement on the distilled water sample showed values of permittivity similar to those found in the literature [ 31 , 41 , 42 ]. The complex permittivity of water in the frequency range from 0.2 GHz to 20 GHz is influenced by the orientation polarization phenomenon.…”

Section: Discussionsupporting

confidence: 85%

Open-Ended Coaxial Probe Measurements of Complex Dielectric Permittivity in Diesel-Contaminated Soil during Bioremediation

Vergnano

Godio

Raffa

et al. 2020

Sensors

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In the bioremediation field, geophysical techniques are commonly applied, at lab scale and field scale, to perform the characterization and the monitoring of contaminated soils. We propose a method for detecting the dielectric properties of contaminated soil during a process of bioremediation. An open-ended coaxial probe measured the complex dielectric permittivity (between 0.2 and 20 GHz) on a series of six soil microcosms contaminated by diesel oil (13.5% Voil/Vtot). The microcosms had different moisture content (13%, 19%, and 24% Vw/Vtot) and different salinity due to the addition of nutrients (22 and 15 g/L). The real and the imaginary component of the complex dielectric permittivity were evaluated at the initial stage of contamination and after 130 days. In almost all microcosms, the real component showed a significant decrease (up to 2 units) at all frequencies. The results revealed that the changes in the real part of the dielectric permittivity are related to the amount of degradation and loss in moisture content. The imaginary component, mainly linked to the electrical conductivity of the soil, shows a significant drop to almost 0 at low frequencies. This could be explained by a salt depletion during bioremediation. Despite a moderate accuracy reduction compared to measurements performed on liquid media, this technology can be successfully applied to granular materials such as soil. The open-ended coaxial probe is a promising instrument to check the dielectric properties of soil to characterize or monitor a bioremediation process.

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Section: Discussionsupporting

confidence: 85%

Open-Ended Coaxial Probe Measurements of Complex Dielectric Permittivity in Diesel-Contaminated Soil during Bioremediation

Vergnano

Godio

Raffa

et al. 2020

Sensors

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“…However, radar backscatter is more closely related to permittivity than stem radius. Diurnal variations in stem permittivity are more sinusoidal than those measured by dendrometers [46], [58]. This discrepancy may partially be explained by the nonlinear relationship between permittivity and backscatter [20].…”

Section: Discussionmentioning

confidence: 84%

“…18. This is because part of the free water in the trees turns into ice, which has a significantly lower permittivity compared to liquid water [45], [46], resulting in weaker reflections of electromagnetic waves. The distribution HH (all) of canopy backscatter during freezing temperatures is bimodal, showing that the vegetation does not freeze at the exact onset of sub-zero air temperatures.…”

Section: B Effects Of Freeze-thaw Cyclesmentioning

confidence: 99%

Temporal Characteristics of P-Band Tomographic Radar Backscatter of a Boreal Forest

Monteith

Ulander

2021

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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Temporal variations in synthetic aperture radar (SAR) backscatter over forests are of concern for any SAR mission with the goal of estimating forest parameters from SAR data. In this article, a densely sampled, two-year long time series of P-band (420 to 450 MHz) boreal forest backscatter, acquired by a tower-based radar, is analyzed. The experiment setup provides time series data at multiple polarizations. Tomographic capabilities allow the separation of backscatter at different heights within the forest. Temporal variations of these multipolarized, tomographic radar observations are characterized and quantified. The mechanisms studied are seasonal variations, effects of freezing conditions, diurnal variations, effects of wind and the effects of rainfall on backscatter. An emphasis is placed on upper-canopy backscatter, which has been shown to be a robust proxy for forest biomass. The canopy backscatter was more stable than ground-level backscatter during non-frozen conditions, supporting forest parameter retrieval approaches based on tomography or interferometric ground notching. Large backscatter variations during frozen conditions, which may be detected using cross-polarised backscatter observations, can result in large errors in forest parameter estimates. Diurnal backscatter variations observed during hot periods were likely connected to tree water transport and storage mechanisms. Backscatter changes were also observed during strong winds. These variations were small in comparison to the variations due to freeze-thaw and soil moisture changes and should not result in significant forest parameter estimation errors. The presented results are useful for designing physically based and semiempirical scattering models that account for temporal changes in scattering characteristics.

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“…Likewise, plants, vegetables, and fruits also possess dielectric properties that indicate a consistent absorption of the RF energy in wireless communication bands. Free space transmission technique and open ended coaxial probe technique have been primarily reported for dielectric properties characterization of different crop, vegetable, fruit and plant samples [26][27][28][29][30][31][32]. In addition, SAR data have been reported as per ICNIRP [33,34], FCC [35], and revised Indian [36][37][38][39][40] electromagnetic regulatory guidelines for different fruit models in recent times.…”

Section: Introductionmentioning

confidence: 99%

“…To this notion, Catharanthus roseus plant containing green leaves, green stem, and pink flower have been chosen as prototype. Dielectric properties of fresh leaf, flower, and stem samples have been characterized using open ended coaxial probe technique [28][29][30][31][32]. Next, a typical three-dimensional Catharanthus roseus plant model has been developed.…”

Section: Introductionmentioning

confidence: 99%

Contrast in Specific Absorption Rate for a Typical Plant Model Due to Discrepancy Among Global and National Electromagnetic Standards

Kundu¹,

Gupta²,

Mallick³

2021

PIER M

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Different global and national electromagnetic regulatory standards have been developed based upon significantly diversified premises, developmental backgrounds, and objectives to safeguard life. Some standards aim at minimizing short duration thermal effects; some try to mitigate non-thermal effects over prolonged duration; and rest have adopted precautionary limits. As a consequence, these global and national electromagnetic standards substantially differ from each other. Moreover, in spite of lossy dielectric nature of plant tissues, electromagnetic energy absorption rate level estimations for a complete plant model have neither been reported in literature nor been considered while preparing safety standards. To this end, Specific Absorption Rate levels have been estimated for a typical Catharanthus roseus plant model-typical geometric shape of the plant prototype has been modelled considering the most practical scenario. Detailed analyses on variation of Specific Absorption Rate levels due to wide discrepancy among the existing electromagnetic regulatory standards have been reported in a quantitative manner. This particular work encompasses dielectric properties measurement of different Catharanthus roseus plant samples, modelling a typical Catharanthus roseus plant containing leaves, flower, and twig with appropriate dielectric properties defined, and finally the simulation-based investigations to estimate the variation in Specific Absorption Rate levels based on the contrasting electromagnetic exposure standards. Specific Absorption Rate levels have been reported at five different telecommunication bands as per two occupational and four public exposure scenarios. Variations among the estimated Specific Absorption Rate levels have been noted to be significant and presented in detail in this article. A total of thirty rigorous simulations have been carried out along with one hundred and twenty Specific Absorption Rate data evaluations to ensure accurate comparison among different electromagnetic standards. Noted vast variations among estimated Specific Absorption Rate levels based on contrasting electromagnetic standards over the frequencies indicate the necessity of re-evaluating all existing guidelines and also call for the need of maintaining a global uniformity among the existing electromagnetic standards worldwide.

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

Cited by 29 publications

References 62 publications

Open-Ended Coaxial Probe Measurements of Complex Dielectric Permittivity in Diesel-Contaminated Soil during Bioremediation

Open-Ended Coaxial Probe Measurements of Complex Dielectric Permittivity in Diesel-Contaminated Soil during Bioremediation

Temporal Characteristics of P-Band Tomographic Radar Backscatter of a Boreal Forest

Contrast in Specific Absorption Rate for a Typical Plant Model Due to Discrepancy Among Global and National Electromagnetic Standards

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