Ferromagnetic Nanoparticles in Broad Band Radar Absorbers

The construction of thin, broad band absorbers using magnetic materials rely on the presence of high magnetic losses. In this paper, we discuss the possibilities of realizing these losses by studying the Landau-Lifshitz-Gilbert model of ferromagnetic materials. The small signal permeability derived from this nonlinear model is then combined with modern homogenization techniques to study a composite material made up of nanosized magnetic particles embedded in a background material. This is used to produce bounds in the complex plane as to what effective material parameters can be achieved from such a composite material.