Measuring Complex Permeability of Ferromagnetic Thin Films using Microstrip Transmission Method

Abstract

A transmission method is proposed to measure the complex permeability of ferromagnetic thin films in the frequency range of 100 MHz–18 GHz. The air microstrip is used as measurement fixture; S-parameters are measured by vector network analyzer (VNA). Ferromagnetic thin film samples deposited on silicon substrate with thickness less than 90 nm are measured. Effective permeability is deduced from the s-parameters loaded with and without thin films, and complex permeability of thin films is extracted from the effective permeability. The experimental results show that, using the method proposed in this paper, the complex permeability of thin films can be determined accurately up to 18 GHz.