scholarly journals New Approach for Calculating the Effective Dielectric Constant of the Moist Soil for Microwaves

2017 ◽  
Vol 9 (7) ◽  
pp. 732 ◽  
Author(s):  
Chang-Hwan Park ◽  
Andreas Behrendt ◽  
Ellsworth LeDrew ◽  
Volker Wulfmeyer
Keyword(s):  
Dielectric Constant ◽  
Effective Dielectric Constant ◽  
Moist Soil ◽  
New Approach

Modeling of Microwave Scattering From Cloud Ice Crystal Aggregates and Melting Aggregates: A New Approach

2010 ◽  
Vol 7 (3) ◽  
pp. 572-576 ◽  
Author(s):  
Giovanni Botta ◽  
Kültegin Aydin ◽  
Johannes Verlinde
Keyword(s):  
Dielectric Constant ◽  
Cross Sections ◽  
Melting Process ◽  
Effective Dielectric Constant ◽  
Ice Crystal ◽  
New Approach ◽  
Microwave Scattering ◽  
Spheroidal Shape ◽  
Cloud Ice ◽  
Scattering Cross Sections

Ice crystal aggregates and their melting process are modeled with a new approach for determining their microwave scattering characteristics and are compared with those obtained using effective dielectric constant representations. The aggregates are constructed from columnar crystals of random lengths (with the width being a function of the length), which are composed of a string of touching ice spheres with diameters equal to the column's width. The aggregates are melted using a model that incorporates the primary aspects of experimentally observed features of the melting process. The generalized multiparticle Mie method is used for computing the scattering cross sections of the dry and melting aggregates. The T-matrix method is used for computations involving a bulk representation of each aggregate with an effective dielectric constant model and an oblate spheroidal shape. The 3- and 35.6-GHz backscattering cross sections show significant differences between the two methods for both dry and melting aggregates. For sizes larger than 3 mm, these differences range from several decibels at 3 GHz to well over 7 dB at 35.6 GHz. Significant differences are also observed in the extinction cross sections during the melting process. It is concluded that the effective dielectric constant models of dry and melting ice crystal aggregates do not represent the interactions between the constituent crystals (and water droplets during melting) of the aggregates very well. Hence, bulk models must be used with caution particularly at millimeter wavelengths.

Measurement of effective dielectric constant : A comparison

2011 ◽  
Author(s):  
Aakashdeep ◽  
Saurav Kr. Basu ◽  
G. V. Ujjwal ◽  
Sakshi Kumari ◽  
V. R. Gupta
Keyword(s):  
Dielectric Constant ◽  
Effective Dielectric Constant

Contributions to Silicon-Hydrogen Bond-Stretching Frequency in Amorphous Si Alloys

1992 ◽  
Vol 258 ◽  
Author(s):  
Z. Jing ◽  
J. L. Whitten ◽  
G. Lucovsky
Keyword(s):  
Experimental Data ◽  
Hydrogen Bond ◽  
Dielectric Constant ◽  
Ab Initio ◽  
Effective Dielectric Constant ◽  
Bond Energies ◽  
Calculated Frequency ◽  
Bond Stretching ◽  
Amorphous Si ◽  
Good Agreement

ABSTRACTWe have performed ab initio calculations and determined the bond-energies and vibrational frequencies of Si-H groups that are: i) attached to Si-atoms as their immediate, and also more distant neighbors; and ii) attached to three O-atoms as their immediate neighbors, but are connected to an all Si-atom matrix. These arrangements simulate bonding geometries on Si surfaces, and the calculated frequency for i) is in good agreement with that of an Si-H group on an Si surface. To compare these results with a-Si:H alloys it is necessary to take into account an additional factor: the effective dielectric constant of the host. We show how to do this, demonstrating the way results of the ab initio calculations should then be compared with experimental data.

scholarly journals Characterization of percolation behavior in conductor–dielectric 0-3 composites

2014 ◽  
Vol 04 (04) ◽  
pp. 1450035 ◽  
Author(s):  
Lin Zhang ◽  
Patrick Bass ◽  
Zhi-Min Dang ◽  
Z.-Y. Cheng
Keyword(s):  
Dielectric Constant ◽  
Percolation Threshold ◽  
Frequency Dependence ◽  
Experimental Results ◽  
Effective Dielectric Constant ◽  
Filler Concentration ◽  
Percolation Behavior ◽  
The Matrix ◽  
The Relationship

The equation ε eff ∝ (ϕc - ϕ)-s which shows the relationship between effective dielectric constant (εeff) and the filler concentration (φ), is widely used to determine the percolation behavior and obtain parameters, such as percolation threshold φc and the power constant s in conductor–dielectric composites (CDCs). Six different systems of CDCs were used to check the expression by fitting experimental results. It is found that the equation can fit the experimental results at any frequency. However, it is found that the fitting constants do not reflect the real percolation behavior of the composites. It is found that the dielectric constant is strongly dependent on the frequency, which is mainly due to the fact that the frequency dependence of the dielectric constant for the composites close to φc is almost independent of the matrix.

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