Effective permittivity of planar composites with randomly or periodically distributed conducting fibers

Abstract

Theoretical and experimental studies have been conducted on the effective electromagnetic properties of planar composites at microwave frequencies, with embedded conductive fibers of various volume concentrations. Two types of distribution are considered: random and periodic. Experimental results for the transmission coefficient and effective permittivity are obtained via the free space method. Simulation results are obtained using the finite element method (FEM). Good agreement is found between the measured and computed results, indicating the suitability of the FEM as a theoretical modeling tool for such composites, as compared to other numerical methods, such as the method of moments. It is also found that the type of distribution affects the effective permittivity of the composites: lower microwave permittivity with broader peak response is observed for composites with randomly distributed fibers, in comparison to that with periodically distributed fibers.