Ring-Resonator Loaded Transmission Line for Crack Detection

In this paper, a transmission line (TL) loaded by a compact ring resonator array is designed for crack monitoring. The ring resonators are interleaved and located on the two sides of TL to generate a uniform field distribution in space. The crack depth/width can be characterized by the resonant frequency. The simulation results show that the proposed sensor can discriminate sub-millimeter cracks, with an averaged depth detection sensitivity of -121.7 MHz/mm
²
, and an averaged width detection sensitivity of -148.3 MHz/mm
²
. This paper provides a paradigm for monitoring the health of large but complex metallic structures.