Sensitivity Analysis of an Edge-Fed Microstrip Patch Antenna Strain Sensor to Detect Surface Strains

Damage detection through strain sensing is inevitable in structural health monitoring (SHM) for implementing preventive measures against the failure of a mechanical component or a civil structure. Strain sensors based on patch antennas are gaining importance due to their simple geometry and ease of fabrication. This work presents the effect of longitudinal and transverse deformation on the patch antenna strain sensor characteristics. Structural and electromagnetic simulations are performed for various loads using a commercial FEM package. The variation in the reflection coefficient with resonant frequency is analyzed for different strain levels up to the elastic limit of the sensor. It is observed that the edge-fed patch antenna can be used in cases of higher strain levels. However, the patch antenna sensor is less sensitive at lower strain levels. The patch antenna sensor effectively decouples the directional strains, making it effective for bidirectional strain sensing using a single element.