Possibility of using a coaxial cable as a distributed strain sensor by time domain reflectometry

In this paper, the possibility of using coaxial cables as distributed strain sensors by time domain reflectometry is studied. Analytical analysis is conducted on the relation between the distributed axial strain and the change of characteristic impedance as well as on the relation between the change of characteristic impedance and the voltage of the reflected wave. The analysis leads to the establishment of the quantitative relation between the distributed axial strains of a coaxial cable and the change in the voltage of the reflected wave. It is demonstrated that the voltage of the reflected wave can be used to measure the magnitude and determine the location of the axial strains in a coaxial cable. Furthermore, a good linearity is obtained when the axial strains are small. The investigation highlights the potential of coaxial cables as distributed strain sensors. Finally, the existing problems for such sensors are discussed.