Chair of Microwave Engineering

moisture measurements

Handsonde




Applications

 

Hansonde

 

 

 

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

 



Resonator

Resonator

 

 

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

 

Grafik von Resonanz

 

 

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

 



Calibration

 

Kalibration

 

 

  • 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

 

Interpolation

 

 

  • 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

 

Blockschaltbild

 

 

 



Structure

 

 

 

  • 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.