Microwave Nondestructive Evaluation Using Spiral Inductor Probe

Non-Destructive Testing (NDT) techniques are crucial in various civil and military applications for detecting and characterizing defects. The NDT methods contribute to the sustainability, operational readiness, and overall success of civil and military engineering. However, conventional NDT methods need improvement to detect delamination in carbon fibre reinforced polymer (CFRP) composite. The Microwave NDT method using a spiral inductor probe has the potential to detect a hidden or subsurface defect in CFRP. Unlike conventional eddy current NDT method that mainly detects surface and near-surface defects. Thus, the sensor can penetrate deeper into CFRP, increasing the chance of detecting concealed delamination defects. The probe is analyzed using CST Microwave Studio's computer simulation software. The designed spiral inductor exhibits a return loss of -24 dB and resonates at 419 MHz. The spatial resolution and sensitivity of the proposed probe are assessed using line scans and regression analysis. The probe demonstrates high spatial resolution and sensitivity in detecting defects at depths ranging from 0.5 to 3.0 mm. The performance of the proposed probe indicates that resonant frequencies decrease proportionally with the depth of the defect.