Crack Detection in Metallic Structures Using Planar Monopole Antenna

In this paper, a monopole antenna is devised to detect the presence of a crack for Structural Health Monitoring (SHM) application. The performance parameters of the antenna sensor are numerically evaluated using Finite Element Analysis (FEA) and experimentally validated. A crack is introduced as a perturbation in the ground plane of the monopole antenna, resembling the metallic part of the structure that is monitored. The linear resonance frequency shifts in the monopole antenna validate the presence and propagation of a crack in the structure under observation. Different orientations and dimensions of the crack are analyzed to study the sensitivity of the monopole antenna as a sensor for crack detection with a higher sensitivity of -41.2 MHz/mm. The influence of the crack on the gain and radiation patterns is also addressed to evaluate the performance degradation. The simulation and experiment results ensure the ability of the proposed antenna sensor to detect minute structural defects in metallic structures.