Reflection Method for Shielding Effectiveness Measurement: Complex Materials Without Prior Knowledge

This study proposes a reflection-only shielding effectiveness (SE) measurement method for complex electromagnetic (EM) planar samples with anisotropy (with diagonal constitutive parameter matrices), high loss, and strong dispersion under varying incident angles and polarizations. By constructing an analytical model that maps the reflection coefficients from metal-backed and air-backed configurations to the material’s electrical length and impedance, and designing a simplified calibration scheme to extract these two sets of reflection coefficients, this method ultimately enables SE calculation without requiring prior knowledge of sample thickness or EM parameters. It demonstrates unique advantages in scenarios where the receiver cannot be placed in the transmission zone and insufficient sample information is available. Additionally, the method simultaneously resolves attenuation and transmission phase through a unified analytical framework. The proposed method was validated through numerical experiments and extended to composite materials. Experimental measurements on carbon fiber and F4B (a low-loss polytetrafluoroethylene-glass composite with εr = 2.65) plates demonstrated the accuracy and reliability of the method.