Ferrite-impregnated fibre-glass composites as microwave absorbers

The absorption of microwaves in a composite containing a random distribution of iron-oxide particles embedded in fiberglass composites is considered. Generally, iron-oxide particles in the form of spheres or cylinders are held together by a binder such as fiberglass. Since weight and structural integrity of the composite are also of concern in many applications, it is desirable to choose the optimum volume fraction of iron-oxide particles and adjust the shape, size, and distribution of particles to obtain the required mass density and microwave absorbing properties. A short review of mixture theories is given. Results are shown for spherical conducting particles in a pure dielectric host medium and are compared with experimental data. Results (real and imaginary parts of the permittivity and permeability, loss tangent, reflection coefficient, and attenuation per unit length) on iron-oxide impregnated fiberglass composites in the frequency range of 1 to 12 GHz are reported