Fixed low-frequency electrical parameter measurement on rock cores with the coaxial probe method

In the borehole radar detection, the dielectric permittivity testing is crucial to the accuracy of the detection depth. Usually, the dielectric permittivity εr$ \varepsilon_{r} $ is a dynamic parameter even in the same medium with different structures, or in the different physical environments. Therefore, testing methods for the dielectric permittivity measurement of the sample should be adjusted to fit the local conditions. However, it is usually difficult to measure the dielectric permittivity directly so far. In this paper, we present the design and fabrication of a fixed low-frequency electrical parameter testing system with open-ended coaxial probe technique to meet the desired requirement in borehole radar detection. Using this testing system, the dielectric permittivity of the rock core samples and non-rock samples was tested directly. The measured results and simulation results by CST are in good agreement, which demonstrated the accuracy of the measuring technique and the significance for microwave remote sensing in the dielectric permittivity measurements. So, our method could be extended to the application in borehole radar detection.