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Mini TDR

Smallest commercially available TDR sensor

Smallest and most affordable TDR sensor for precision monitoring of soil volumetric water content.


The East 30 Sensors Mini TDR sensor is ideal for many applications, especially

High EC soils

Soils with high clay content

Soil Columns

Volumetric water content monitoring

The Mini TDR sensor is the smallest on the market, which reduces signal attenuation in soils with high electrical conductivity and high clay content. This TDR is designed to be rugged and accurate in many settings, while maintaining a small size. It is available in two models, a round head for use in soil columns, or a longer rectangular head for field use.

The East 30 Sensors Mini-TDR is designed to be used with the CSI TDR200, but can be used with any TDR Coaxial cable tester or control and analysis program.

Mini TDR for high EC field installations


  • Needle dimensions: 6cm x 1.4mm

  • Needle spacing: 6 mm

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

  • Cable length: 2m

     (additional cable available up to 10m)


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.


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. 

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