The Influence of Particle Size and Volume Fraction on Hybrid Ferrite Microwave Absorbers

As 5G technology becomes ubiquitous and the internet of things expands, sources of microwave EMI are rapidly increasing, and the threat of coupling EM energy into susceptible electronic circuits.  Mitigating this threat requires compact, lightweight broadband absorbers to protect sensitive electronics.  Magnetite, MnZn ferrite, and NiZn ferrite, alone and in conjunction, have the potential to meet the energy density and EM attenuation performance needs.  However, optimizing the absorption loss requires improved understanding of the role of particle size and volume fraction on the complex permittivity and permeability of these materials.  This presentation discusses experimental investigation of the particle size and volume fraction on the absorption losses of these ferrites.  Complex permeability and permittivity measurements were conducted to identify the absorption mechanisms.  We present a possible explanation of these results in the context of Snoek’s limit and the Landau-Lifshitz theory of permeability.

This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.