Analysis on microwave absorption properties of M-type hexagonal ferrites

The microwave absorption properties of M-type hexagonal ferrites were investigated. The complex permeability and permittivity were measured using a network analyzer. In the BoFe(12-x)(TiCo) O-x(19) system, the ferrimagnetic resonance frequency shifts down to the 1 similar to 20 GHz range, when x is increased. Due to the relatively high UP value, thin matching thicknesses of 0.9 similar to 1.9mm were obtained in the 5 similar to 10 GHz range. The frequency characteristics of mu(r)' and mu(r)" were analyzed and simulated successfully using a parallel resonant circuit model based on the crystalline structure. Dual peak characteristics of mu(r)" were observed for a certain sintering temperature and duration, and a relative absorption bandwidth of 16 % was obtained. The simulation showed that a wider absorption bandwidth of 33 % may be possible.