Shaft-Mounted Time Domain Reflectometry Probe for Water Content and Electrical Conductivity Measurements

摘要

A new shaft-mounted time domain reflectometry (TDR) probe design is described and evaluated. In contrast to previous shaft-mounted TDR probes (SMPs), the new design may be used to measure both dielectric constant (K_a) and bulk electrical conductivity (_a). Two SMP prototypes, 0.03 and 0.04 m long and having diameters of 0.006 m, were evaluated. The probes were calibrated in several fluids having different K_a and _a. A primary advantage of the SMP is minimal physical probe length without sacrificing accuracy of K_a readings. Accuracy of K_a measurements for the new probes was similar to that of standard 0.20-m-long three-rod probes.