Advances in Radio Science
www.adv-radio-sci.net
1684-9965
1684-9973
6
Kleinheubacher Berichte 2007
2008
10.5194/ars-6-1-2008
http://www.adv-radio-sci.net/6/1/2008/
http://www.adv-radio-sci.net/6/1/2008/ars-6-1-2008.html
http://www.adv-radio-sci.net/6/1/2008/ars-6-1-2008.pdf
1
4
2008-05-26
Time domain reflectrometry measurements using a movable obstacle for the determination of dielectric profiles
B. Will
bianca.will@rub.de
M. Gerding
S. Schultz
B. Schiek
Ruhr-University Bochum, Institute of High Frequency Engineering, Universitätsstr. 150, 44801 Bochum, Germany
Microwave techniques for the measurement of the permittivity of
soils including the water content of soils and other materials,
especially TDR (time domain reflectometry), have become accepted as
routine measurement techniques. This summary deals with an advanced
use of the TDR principle for the determination of the water content
of soil along a probe. The basis of the advanced TDR technique is a
waveguide, which is inserted into the soil for obtaining
measurements of the effective soil permittivity, from which the
water content is estimated, and an obstacle, which can mechanically
be moved along the probe and which acts as a reference reflection
for the TDR system with an exactly known position. Based on the
known mechanical position of the reference reflection, the measured
electrical position can be used as a measure for the effective
dielectric constant of the environment. Thus, it is possible to
determine the effective dielectric constant with a spatial
resolution given by the step size of the obstacle displacement.
<br><br>
A conventional industrial TDR-system, operating in the
baseband, is used for the signal generation and for the evaluation
of the pulse delay time of the obstacle reflection. Thus, a cost
effective method for the acquisition of the dielectric measurement
data is available.
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