Shift of resonance frequency of long conducting fibers embedded in a composite

Abstract

An experimental study on the dipole resonance of long high-conducting fibers embedded in an inhomogeneous composite sheet was conducted. The location of the resonance characterizes the effect of the inhomogeneous environment on the electromagnetic response of the fibers. It is shown that the resonance frequency is determined completely by the thickness and permittivity of the composite sheet, in particular, with the anisotropy of the permittivity. No effect due to inhomogeneity of the environment is observed. This is in disagreement with the scale-dependent effective medium theory (SDEMT) that is conventionally exploited to model the permittivity of fiber-filled composites, because this theory shows that the response of the fibers depends on the inhomogeneity scale of the environment. Therefore, although the SDEMT provides qualitative agreement with the observed behavior of fiber-filled composites, it must be further improved to obtain better quantitative agreement with experimental data. The experimental data obtained can also be useful to the development of microwave dielectrics with complex frequency dispersion behavior, which are necessary for many microwave applications.

Unified Spectral Technique Application for Study of Radiator Behavior Near Planar Layered Composites

“…the dielectric base. The frequency characteristics for the permittivity of the composite are calculated using the Maxwell Garnett effective medium formulation [24][25][26][27][28][29][30][31], described in Appendix C, and they are shown in Figures 11(a), (b). The base dielectric is assumed to be non-dispersive (ε b = 2.2).…”

Microwave Dielectric Properties of Carbon Nanotube Composites

“…The planar CF composites are anisotropic with degraded dielectric response across the plane. Due to the heterogeneity of the composites, a surface layer of millimeters in thickness appears with properties different from those of the bulk composites (Simovski, et al, 2000 andMatitsine, et al, 2003). This gives rise to difficulty in modeling and designing composites with desired properties.…”

Modeling of Shielding Composite Materials and Structures for Microwave Frequencies

“…An advantage of using carbon fibers in composite materials is that its range of pronounced frequency dispersion is shifted to the RF and lower frequency portion of the microwave band [17]. To characterize electromagnetic properties of composite media, it is important to know the electromagnetic parameters of a host (matrix, base) material and inclusions.…”