Dual-mode Non-Destructive Evaluation Technique Using a Single Spiral Coil

This paper proposes a combined inductive and capacitive non-destructive evaluation technique using a single spiral coil on a Printed Circuit Board (PCB). By measuring the coil impedance at frequencies below and above the resonant frequency, the inductive and capacitive responses can be separated to some extent. Equivalent circuit analysis, Finite Element simulations and experimental research are applied. A system to implement this technique has been constructed, and its feasibility in imaging defects in insulators, conductors and a hybrid structure has been verified.