Microwave thermal imaging system for debonding detection of radar absorbing materials.

This article focuses on the development and evaluation of a microwave thermal imaging system (MTIS) designed for in situ detection of debonding defects in radar absorbing materials (RAMs), which are critical for radar stealth technology. The MTIS integrates two non-destructive testing methods—long-pulse microwave thermography (LPMT) and microwave lock-in thermography (MLIT)—operating at 5.8 GHz with a maximum output power of 20 W and a detection area of 90 × 90 mm². Experimental results indicate that LPMT enables rapid preliminary detection of larger debonding defects, while MLIT combined with principal component analysis (PCA) enhances the detection of smaller defects with improved signal-to-noise ratio, despite lower testing efficiency and noise challenges in the Fourier transform method. The system's design includes a beam-symmetric horn antenna and a microwave output system, and it is compatible with robotic arms for multi-directional inspection, supporting its potential application in routine maintenance of RAM-coated aircraft surfaces.