Journal ArticleDOI
Microwave Dielectric Properties of Plant Materials
Fawwaz T. Ulaby,R. P. Jedlicka +1 more
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In this paper, three waveguide transmission systems covering the 1-2, 3.5-6.5, and 7.5 GHz bands were used to measure the dielectric properties of vegetation material as a function of moisture content and microwave frequency.Abstract:
Three waveguide transmission systems covering the 1-2, 3.5-6.5, and 7.5-8.5 GHz bands were used to measure the dielectric properties of vegetation material as a function of moisture content and microwave frequency. The materials measured included, primarily, the leaves and stalks of corn and wheat. Dielectric measurements also were made of the liquid included in the vegetation material after it was extracted from the vegetation by mechanical means. The extracted liquids were found to have an equivalent NaCl salinity of about 10 per mil, which can have a significant effect on the dielectric loss at frequencies below 5 GHz. The results of attempts to model the dielectric constant of the vegetation-water mixture in terms of the dielectric constants and volume fractions of its constituent parts (i. e., bulk vegetation, air, bound water, and free water) are discussed. Additionally, measurements of the temporal variations in the total attenuation at 10.2 GHz are presented for a corn canopy and a soybean canopy.read more
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Microwave Remote Sensing
TL;DR: The sections in this article are==================�€�€€ Æ£££€££ ££€ ££ £€ £ £ £€£ £ ££ €££ € £££ $££
Journal ArticleDOI
Microwave Dielectric Spectrum of Vegetation - Part II: Dual-Dispersion Model
TL;DR: In this article, a Debye-Cole dual-dispersion dielectric model consisting of a component that accounts for the volume fraction occupied by water in free form and another component comprised of water molecules bound to bulk-vegetation molecules is presented.
Microwave Dielectric Spectrum ofVegetation PartII:Dual-Dispersion Model
TL;DR: In this paper, a Debye-Cole dual-dispersion dielectric model consisting of a component that accounts for the volume fraction occupied by water in free-form and another component that accounts for the vol- umefraction occupied by them mixture comprised of watermolecules boundtobulk-vegetation molecules was proposed.
Journal ArticleDOI
Active Microwave Soil Moisture Research
M. Craig Dobson,Fawwaz T. Ulaby +1 more
TL;DR: In this paper, the authors summarized the progress achieved in the active microwave remote sensing of soil moisture during the four years of the AgRISTARS program and identified potentially powerful approaches to implement empirical results over large areas on a repetitive basis.
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Nondestructive Characterization and Imaging of Wood
TL;DR: In this article, the authors present a list of color plate notation for computed tomography (Ctomography) including: ionizing radiation, thermal imaging, Microwave Imaging, Ultrasonic Imaging, Nuclear Magnetic Resonance and Neutron Imaging.
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Journal ArticleDOI
An improved model for the dielectric constant of sea water at microwave frequencies
TL;DR: In this article, the dielectric constant of sea water has been measured at S-band and L-band with a quoted uncertainty of tenths of a percent, and expressions are developed which will yield computations of brightness temperature having an error of no more than 0.3 K for an undisturbed sea at frequencies lower than X-band.
Journal ArticleDOI
The effective permeability of mixtures of solids
D. Polder,J.H. van Santeen +1 more
TL;DR: In this paper, the effective dielectric constant for a material, consisting of a medium in which solid particles or empty holes with various dielectrics constants are packed together and in which the individual particles or holes are assumed to be ellipsoidical.
Journal ArticleDOI
Generalized approach to multiphase dielectric mixture theory
TL;DR: In this article, a self-consistent solution for finding the complex dielectric constant of a multiphase mixture with confocal ellipsoidal shell inclusions is presented.
Journal ArticleDOI
Dielectric Properties of Heterogeneous Mixtures Containing Water
TL;DR: In this article, the dielectric properties of heterogeneous mixtures are treated, and especially the properties of mixtures containing water, in order to elucidate many of the phenomena which contribute to the general behaviour of many systems when brought into a microwave field.
Journal ArticleDOI
Effects of Vegetation Cover on the Microwave Radiometric Sensitivity to Soil Moisture
TL;DR: In this paper, the reduction in sensitivity of the microwave brightness temperature to soil moisture content due to vegetation cover was analyzed using airborne observations made at 1.4 and 5 GHz during six flights in 1978 over a test site near Colby, Kansas.