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Mini TDR

Smallest commercially available TDR sensor

Applications

  • Measuring Volumetric Water content of Soils

  • Ideal for use in soil columns, soils with high clay contents or high electrical conductivity where the signal is easily attenuated on larger TDR probes.

  • Circular design allows for easy insertion into soil columns 

Specifications

  • Needle dimensions: 6cm x 1.4mm diameter, Spacing: 6 mm

  • Head dimensions: 25 x 13 x 13 mm long (T3F model) or with a round head, 22mm diameter (T3R)

  • Cable length: 2m (additional cable available up to 10m)

 

Theory

TDR is an accepted and standard method for measuring Volumetric Water Content in Soils. In conjunction with a TDR control and interface system with coaxial connections (TDR200 by Campbell Scientific Inc. is recommended), an electromagnetic wave is applied, and the waveform generated can be analyzed to obtain water content. In high salinity soils, the reflected TDR signal amplitude decreases due to electrical conduction between needles. This allows for an electrical conductivity measurement, but in soils with high electrical conductivity, this can create inaccuracies and poor resolution in the volumetric water content measurement. However, by shortening the needle length of the TDR sensor, the signal attenuation can be minimized. The TDR sensors made by East 30 Sensors are the shortest on the market, to provide accurate results in a variety of soil types and salinities.

What you need

  • TDR coaxial cable tester 

  • Or TDR control/analysis system

In the Package

Each probe comes with a certificate of calibration and a calculated probe constant. Easily interfaces with CSI TDR200 in combination with specific CSI dataloggers.

Selected Publications

Das, D.B., Mirsaei,M. 2012. Dynamic Effects in Capillary Pressure Relationships for Two-Phase Flow in Porous Media: Experiments and Numerical Analyses. AlCHe Vol. 58, Issue 12, pp. 3891-3903.

Das, D.B., Mirzaei,M. 2013. Experimental measurement of dynamic effect in capillary pressure relationship for two‐phase flow in weakly layered porous media. AlCHe Vol. 59, Issue 5, pp. 1723-1734.

Kameyama, K. Miyamoto, T. Shiono, T. 2014. Influence of biochar incorporation on TDR‐based soil water content measurements. European Journal of Soil Science Vol. 65, Issue 1, pp. 105-112.