- journal_title：Vadose Zone Journal
- Contributor：Mathis Nussberger ; Hansruedi Benedickter ; Werner Bächtold ; Hannes Flühler ; Hans Wunderli
- Publisher：Soil Science Society of America
- Date：2005-
- Format：text/html
- Language：en
- Identifier：10.2136/vzj2004.0093
- journal_abbrev：Vadose Zone Journal
- issn：1539-1663
- volume：4
- issue：3
- firstpage：551
- section：ORIGINAL RESEARCH
Time domain reflectometry (TDR) probes consisting of one conducting rod and a wave mode converter are an alternative configuration that overcomes some of the disadvantages of conventional probes. We examined four different single-rod probes (SRPs) and a two-rod probe for sensitivity to a small and a large conductive scatterer in their vicinity. The SRPs were assembled combining a small and large wave mode converter with an uncoated and coated rod. We found that the volume sampled by SRPs is larger and more symmetric than in the case of a two-rod probe of equal size. A comparison of the mode converters showed a higher loss for the smaller converter but only a small difference concerning the spatial sensitivity. Coating the conducting rod with a high dielectric constant material reduces the spatial sensitivity. One of the SRPs and the two-rod probe were calibrated in a sand tank (particle size 0.08–0.2 mm) with volumetric water content up to 0.35 m3 m−3. The calibration showed only small differences in the measured bulk dielectric constant between the single-rod and the two-rod probe. Based on this study the SRP is a promising new tool for improved TDR measurement of soil moisture.