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Measuring and Modeling of the Dielectric Properties and Attenuation of VegetationThe dielectric properties of vegetation material--primarily agricultural plants--as a function of moisture content and microwave frequency was measured and used to develop dielectric mixing models for the vegetation-water mixture. A model for the loss factor of a vegetation canopy was also developed. During the first phase of this investigation, three waveguide transmission systems covering from 1 to 2-GHz, from 3.5 to 6.5-GHz, and from 7.5 to 8.5-GHz bands were constructed and calibrated. By measuring the magnitude and phase of the field transmission coefficient of a given sample, it was possible to calculate the real and imaginary parts of the complex dielectric constant of the sample. Measurements were made for numerous samples of leaves and stalks of wheat and corn, and for wheat heads. Also, dielectric measurements were made of the liquid included in the vegetation material after extraction by mechanical means. The propagation loss is more than an order of magnitude greater than had previously been assumed. Various types of dielectric mixing models were investigated in terms of the available data, and a propagation model was developed and evaluated against direct canopy attenuation measurements. The canopy measurements were made by transmitting a signal from a radar antenna mounted atop a truck-mounted boom, and using a small antenna mounted on a rail beneath the canopy to receive it.
Document ID
19840013872
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Ulaby, F. T.
(Kansas Univ. Lawrence, KS, United States)
Date Acquired
August 11, 2013
Publication Date
March 1, 1984
Publication Information
Publication: NASA Goddard Space Flight Center Fundamental Remote Sensing Sci. Res. Program, Part 1
Subject Category
Earth Resources And Remote Sensing
Accession Number
84N21940
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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