Effective Permittivity of Shielding Composite Materials for Microwave Frequencies

Abstract

Due to mass constraints, composite materials are possible candidates to replace metal alloys for electromagnetic shielding applications. The design of standard metallic shielding enclosures often relies on finite-element calculations. But in the case of composite materials, the strong dependence on the shielding properties to the microstructure makes the finite-element approach almost impossible. Indeed meshing the microstructure would imply a huge number of elements, incompatible with usual computational resources. We propose in this paper to develop homogenization tools to define the effective electromagnetic properties of composite materials at microwave frequencies. The ratio between the characteristic size of the microstructure and the wavelength is shown to be a key parameter in the homogenization process. The effective properties can then be used as an input for electromagnetic compatibility standard tools, designed for homogeneous media.Index Terms-Effective medium, heterogeneous materials, homogenization, inclusion problem, Maxwell-Garnett model, shielding effectiveness.

Optimized 3-D electromagnetic models of composite materials in microwave frequency range: application to EMC characterization of complex media by statistical means

“…). Thus, different domains including wireless propagation [3] and electromagnetic compatibility [4] have shown a growing interest for theoretical, numerical [5], and/or experimental [6] developments in this framework.…”

“…at macroscopic scale, for instance regarding shielding effectiveness, SE). Various works were proposed to extract the properties of composite materials mixing gas, liquid, and solid phases with solid matrix, respectively for metrological control [7], geoscience remote sensing [8], and electromagnetic compatibility (EMC) [4]. In this context, different methods are based upon effective medium theory (EMT, e.g.…”

Theoretical Approach of Electromagnetic Shielding of Multilayer Conductive Sheets

“…It is observed that the reflection loss and shielding effectiveness increase with angle of incidence for perpendicular polarization and decrease for parallel polarization. Better reflection loss and shielding 2,0x10 7 4,0x10 7 6,0x10 7 8,0x10 7 effectiveness can be obtained if we associate the magnetic and conductor material to conductive polymer. The reflection loss and shielding effectiveness of multilayer's shield (Aluminum-Pani44/PUAluminum) with using, respectively, equations (23) and (25) are plotted as a function of frequency, respectively, in Figures 6(a) and 6(b) at normal (0 • ) and oblique (45 • and 80 • ) incidence.…”

“…Several analytical and numerical models have been proposed and applied to estimate shielding effectiveness of plate shield and the effective EM properties of heterogeneous materials [7][8][9][10]. As for analytical method, there are mainly three kinds of methods to calculate plate shielding effectiveness.…”

From Microscopic to Macroscopic Description of Composite Thin Panels: A Road Map for Their Simulation in Time Domain

“…In a first stage, our concern is to obtain an accurate EM characterization of the thin-panel transmission and reflection properties for normal incidence as a function of frequency. We can distinguish three distinct procedures to obtain these parameters: to perform experimental measurements with standard setups such as ASTM D4935 or its variants [1]- [3], to derive analytical formulations accounting for its microscopic structure [4]- [6], or to carryout simulations of the unit cell with appropriate periodic boundary conditions [6]- [8]. These results can be typically expressed in two frequency-dependent matrix forms: transmission matrices (ABCD) and S-parameters, both linked by well-known equivalence relations [9].…”