METER TEROS 10 - Theory

13
TEROS 10
The TEROS10 VWC measurement sensitivity is contained within a 430-mL volume roughly
depicted in Figure5. Please see the application note Measurement volume of METER
volumetric water content sensors for testing protocol and more thorough analysis.
1 cm
1 cm
5.1 cm2.4 cm
2 cm
7.5 cm
2 cm
2 cm2 cm
 
NOTE: 

3.3 THEORY
TEROS10 sensors use an electromagnetic field to measure the e
a
of the surrounding
medium. The sensor supplies a 70-MHz oscillating wave to the sensor needles, which charge
according to the dielectric of the material. The charge time is proportional to substrate
dielectric and substrate VWC. The TEROS10 microprocessor measures the charge time and
outputs a raw value based on the substrate e
a
. The raw value is then converted to VWC by a
calibration equation specific to the substrate (Section4.1).