Time Domain Reflectometry (TDR) is an ideal, proven method of soil moisture measurement based on the change in soil dielectric constant with changes in soil moisture. Necessary equipment includes a cable tester, soil moisture probes and a computer to record the wave forms, analyze them, and save the soil moisture results. Optional equipment includes a multiplexer for numerous automated readings and extension cables.

The three conductor semi-coaxial wave guide design does not require an impedance matching balun, yet provides a clear signal. The conductors are precision cut for reproducible length among all probes. The handle is rigid epoxy and acrylic, waterproof and suitable for burial or direct insertion into the soil. Custom wave guide and cable lengths are available.