Direct Extraction of Complex Permittivity and Permeability of Materials on a Known-Substrate From Transmission/Reflection Measurements

In this letter, complex permittivity and permeability of single-layer materials on a known substrate are directly extracted from two measured S-parameters ($S_{11}$ and $S_{21}$ ). The frequency-dependent formulas of the complex permittivity and permeability of the single-layer materials are derived for the first time. A thin absorber and a thin low-loss material on a known substrate are measured in the $X$ -band to experimentally validate the proposed technique. We also investigate the proposed technique with a thick low-loss material on a known substrate.