Accurate Permittivity and Permeability Measurement of Composite Broadband Absorbers at Microwave Frequencies

This paper presents complex permittivity and permeability measurements of iron-loaded materials. These materials are found to be useful as microwave absorbers for application in electromagnetic interference reduction. A transmission reflection based waveguide measurement technique has been used for accurately characterizing the materials in the 2 to 40 GHz microwave frequency range. The precise frequency dependence of the constitutive material properties has been determined. The reflection spectrum has been studied to determine the absorption properties of each sample. The materials were combined to form a composite structure that maintained good absorption over a wide range of frequencies. A detailed error analysis has been presented to discuss the sources of errors in the experimental set-up and how these have been minimized in the measurements.