Evaluation of Magnetic Properties of Ceramic Coated Soft Magnetic Composite and its Simulation for Microwave Devices

Abstract

High frequency applications (in GHz) require soft magnetic materials with high resistivity, anisotropy and low losses above the ferromagnetic resonance. In this research work, fabrication of toroid cores of the magnesium compound coated soft magnetic composites (M-SMC) was carried out. High frequency magnetic properties (0.5–8 GHz) and microwave complex properties of the materials were determined using B-H analyzer and vector network analyzer. The reflection and transmission coefficients were calculated using the scattering parameters. Using Nicolson-Ross-Weir algorithm complex permeability and complex permittivity were calculated. Mathematical model for hysteresis based on Preisach Classical Model for hysteresis was developed to simulate the hysteresis of the material. By doing variation in thickness of the sample, a broad range of frequency spanning from 0.5 GHz to 7.5 GHz is covered. The optimum range for reflection coefficient i.e. 0.6–0.9 is in the frequency range of 3–5.5 GHz for samples of thickness in the ranges of 2–4 mm and 6–8 mm. The maximum transmission coefficient obtained was 0.6 in the frequency range of 0.5–1.5 GHz for samples of various thickness ranges viz. 2–5.5 mm and 6.5 to 8 mm. The transmission coefficient of 0.6 was also obtained in high frequency range of 3–5.5 GHz in case of samples of thickness 4–6 mm and above 7 GHz for samples of thickness above 6 mm.