Extension of the Unmatched-Media Time Reversal Method to Locate Longitudinal Soft Defects in Transmission Lines

This paper applies the electromagnetic time reversal method to the identification of the location and to the quantification of the impedance Zd of longitudinal defects along transmission lines. A closed-form expression for the time-reversal current transfer function is derived. This new transfer function benefits from the same properties of that for solid or soft transversal faults, and hence, can be used for locating the defects along the line. Different scenarios are considered ranging from power lines to signals channels for high-speed digital systems at printed circuit board and package level. The results are discussed and used to assess the accuracy and scalability of the proposed method.