Microwave composites filled with thin ferromagnetic films. Part Ⅰ. Theory

摘要

The microwave permeability of composites filled with pieces of film-shaped ferromagnetic inclusions with small thickness and in-plane anisotropy is studied. A rigorous derivation is presented of Acher's constraint for microwave permeability of composites. The effect of eddy currents on the microwave magnetic performance of ferromagnets is discussed. Simple equations are introduced that are useful for estimating this effect. The composites under consideration are shown to be advantageous magnets for microwave applications. The results obtained are used in Part Ⅱ of the paper where the microwave permeability of composites filled with pieces of thin ferromagnetic films is studied experimentally.