Effective Complex Permittivity Determination and Microwave Absorption Properties of a Granular Dielectric Composite Material

Abstract

The Transmission / Reflection (T/R) method for effective complex permittivity determination is employed to characterize granular dielectric composite material over a wideband frequency. This characterization is a starting point for designing a Radar Absorbent Material (RAM) by optimizing the thickness of the composite layer and inclusion concentrations. A series of 2D-simulations of granular composite material (Graphite / Teflon PTFE), in the dilute limit approximation, are performed; and the maximum electromagnetic absorption (i.e., minimum reflection) is reached for different frequency bands. An optimized composite sample has shown a maximum reflection loss of -31.2 dB (>99% power absorption) at 13.7 GHz with a bandwidth (full frequency width at half of the maximum response) of 2.6 GHz in a sample thickness of 4.3 mm and filler concentration of 1.38%. Materials can find applications in suppression of electromagnetic interference and microwave absorbing coatings.