Ultra-thin Coating Materials Sensor Based on Constitutive Parameters Near-zero Media

Microwave absorbing materials, which serve as essential functional components, are increasingly vital to stealth systems in military equipment. Accurate measurement of the electromagnetic parameters of absorbing coatings is crucial for achieving stealth effects. This study introduces a high-precision curved microwave sensor based on constitutive parameters near-zero (CPNZ) media, which uses thickness and complex permittivity as key test parameters. The complex permittivity and thickness of several typical absorbing materials were evaluated and benchmarked against other sensors. The detection limit of a CPNZ sensor for curved thickness is 0.5 mm, and the relative error of relative dielectric constant is less than 8%. Given the material thickness and resonant frequency, the relative error in the inversion of the dielectric constant is less than 3%. The calculated values closely correspond with the reference values, highlighting the CPNZ sensor’s enhanced accuracy and reliability for material characterization.