EFFECTIVE-MEDIUM AT FINITE FREQUENCY - THEORY AND EXPERIMENT

Besides their technological importance in electromagnetic applications , composites materials made of magnetic metal inclusions in an insulat ing matrix provide a stringent test of effective medium theories. Whil e there exists numerous experimental and theoretical studies in the lo ng wavelength approximation, that is, when induced currents can be neg lected, much less information is available on the effects of, e.g., ed dy currents on the effective permeability of composites, especially wh en it comes to a systematic comparison between experimental data and t he various theoretical formulations. We intend to throw some light on this rather intricate problem by comparing experimental data with an e xtension of Bruggeman effective medium theory.