Applications of microwave techniques for aerospace composites

The structural integrity of composite structures can be monitored and evaluated by using microwave-based techniques. In this paper, five different types of microwave methods that can be used for carbon fibre composites are reviewed. Advantages, limitations and applications of these methods are described. Induction, resonance and time domain reflectometry are suitable for near-field non-contact applications, while thermography and antenna-based methods are advantageous for far-field inspections. Due to the conductive characteristic of carbon fibres, the near-field methods are preferred for better signal penetration over the microwave frequency range.