A Measurement Method for Complex Permittivity of Thin-Film Materials Based on the NRW method

This paper presents a specialized method for measuring the complex permittivity of thin-film materials using the transmission-reflection (NRW) technique. We propose a three-layer equivalent network model in a waveguide system to derive the normalized transfer matrix of single-layer thin films from S-parameters, enabling electromagnetic parameter extraction. The proposed method is rigorously validated through full-wave simulations in CST Studio Suite. The results demonstrate accurate complex permittivity characterization for non-magnetic thin-film materials.