Chair of Microwave Engineering

moisture measurements

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Applications

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Mobile moisture measurement e.g. for
Grains
Concrete Walls
Wood, wood products (particleboard manufacture)
Benefits
non-destructive measurement
quick
mobile

 


 

Resonator

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Properties of the resonator
Length: 1/4-Well length
lower end shorted
upper end open, scattered field results
Stray field penetrating measurement instrument

 


 

Resonance Curves

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  • Resonator is detuned by moisture
  • Parameters:
    Resonant frequency and Bandwidth

 


 

Calibration

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  • The wetter the material, the lower the resonant frequency (see picture) and the greater is the reciprocal of the quality factor.
  • Both relationships are linear, the moisture content can be easily determined.
  • In consideration of resonance frequency and quality can be realized in a density-independent moisture measurement.

 


 

Interpolation

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  • The digital operation of the system only a finite number of measurement points
  • Problem: measuring point is not usually at resonance frequency
  • The response curve interpolation is therefore an efficient algorithm.
  • Up to 55 measurements per second are possible

 


 

Block Diagram

 

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Structure

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  • The system consists of inexpensive electronic components
  • The mechanical design of the resonator is simple
  • Cost-effective implementation possible

 


 

 

 

Contact
Dr.-Ing. Frank Daschner
Phone: 0431 / 880-6169
E-mail: fd@tf.uni-kiel.de
 

 

 

Email: fd@tf.uni-kiel.de If interested in publications or other information materials for this project please contact the secretary or to the persons indicated above.