Detection of defects in groove composite structure using a split ring resonator probe

For workpieces with groove composite structure, void defects and uneven filling defects may be introduced during the process of filling the groove with filler materials, which affects the performance and reliability of the product. In this paper, a microwave near-field probe composed of the microstrip line coupled with a split ring resonator is presented for non-destructive testing of filler materials in the groove. The splits of the split-ring resonator are extended, which improves the electric field concentration ability. The resonant frequency shift of the probe is used to analyze the characterization of the defects. Different types of defects with different dimensions and depths are tested in the experiment. The experimental results prove that the proposed probe has the capability to accurately detect defects in the groove composite structure.