The Effect of Fiber Orientation Distribution on the Effective Permittivity of Fiber Composite Materials

Abstract

We numerically and experimentally investigate the effective permittivity of 2D fiber composite materials with arbitrary fiber orientation at microwave frequency. We focus on the effect of fiber orientation distribution (FOD) rather than on the effect of fiber content, aspect ratio, and the matrix itself. We use the generalized equivalent conductor (GEC) method to study the electromagnetic behavior of fibers with an arbitrary orientation distribution numerically. For experimental verification, we measured the transmission coefficient of three cases of models using the free space measurement. The measurement models are classified into three categories according to the FOD. Good agreement is found between the measured and calculated effective permittivities. We also calculate the dielectric dispersion with respect to the standard deviation and frequency, and construct a dispersion curve using curve-fitting from the Lorentz model. The Lorentz model with fitting parameters shows that the FOD does not affect the resonance frequency and quality (Q) factor but only the resonance peak.