Time-domain reflectometry

G. C. Topp, Ty Ferre

Research output: Chapter in Book/Report/Conference proceedingChapter


Time-domain reflectometry (TDR) is an electromagnetic (EM) technique using radar principles at radio frequency to estimate water content and electrical conductivity of soil. Buried parallel rods are inserted into soil, with the velocity of the TDR wave affected by the soil water content. In addition, the magnitude of the wave is decreased by electrical losses associated with the bulk electrical conductivity of the soil. From the dielectric properties of the soil, equations allow for the TDR waveform to be converted to water content and electrical conductivity. TDR has been combined with other measurements such as with tensiometers and the cone penetrometer.

Original languageEnglish (US)
Title of host publicationEncyclopedia of Soils in the Environment, Second Edition
ISBN (Electronic)9780128229743
StatePublished - Jan 1 2023


  • Dielectric constant
  • Electromagnetic
  • Frequency domain
  • Permittivity
  • Rods
  • Salinity
  • Sensor
  • Soil probe
  • Soil water content
  • Time domain reflectometry

ASJC Scopus subject areas

  • General Engineering
  • General Agricultural and Biological Sciences


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