Application of the end element method to screening challenges

E. A. Gushchina

Saint-Petersburg State University of Aerospace Instrumentation

Abstract: The rapid advancement of modern electronics and telecommunications has intensified the need for high-performance electromagnetic interference (EMI) shielding materials. As electronic devices become more compact and operate at higher frequencies, traditional shielding solutions often fall short in providing adequate protection against electromagnetic noise. In this context, composite materials—particularly those incorporating nanoscale conductive or dielectric fillers—have emerged as a highly promising solution due to their tunable electromagnetic properties, lightweight nature, and flexibility.
This study investigates the electromagnetic field distribution within composite materials across a broad frequency spectrum, with a particular emphasis on how the geometry and spatial orientation of nanofillers influence shielding effectiveness. The research focuses on anisotropic nanofillers, such as carbon nanotubes (CNTs), graphene flakes, and other nanostructured carbon-based materials, embedded within polymer matrices. These composites exhibit strong dielectric polarization effects, which play a crucial role in their interaction with incident electromagnetic waves.
The primary goal of this work is to systematically analyze how the shape, aspect ratio, and alignment of nanofillers affect the EMI shielding performance of thin-film composites. To achieve this, a combination of experimental characterization and computational modeling was employed:
$\bullet$ Dielectric Permittivity Measurements – The frequency-dependent dielectric properties of the composites were evaluated to understand their polarization behavior under alternating electromagnetic fields.
$\bullet$ Morphological and Microstructural Analysis – Advanced microscopy techniques (e.g., SEM, TEM) were used to assess filler dispersion, orientation, and percolation networks within the polymer matrix.
$\bullet$ Electromagnetic Shielding Effectiveness (SE) Testing – The composites were subjected to standardized EMI shielding tests across microwave and millimeter-wave frequencies to quantify their attenuation performance.
$\bullet$ Numerical Simulations – Finite-element modeling (FEM) and effective medium theory (EMT) were applied to predict electromagnetic field distribution and losses within the composites.
Elongated nanostructures, such as CNTs, demonstrated enhanced electromagnetic shielding when aligned along the direction of the electric field due to their high aspect ratio and conductive pathways. In contrast, randomly distributed fillers provided more isotropic attenuation, making them suitable for applications requiring uniform shielding in all directions. Plate-like fillers (e.g., graphene) exhibited strong interfacial polarization, contributing to additional dielectric losses at higher frequencies.
Aligned CNT-based composites showed superior shielding efficiency (SE) in the alignment direction, with a notable increase in reflective losses due to improved electrical conductivity. Randomly oriented fillers enhanced absorption losses, as their disordered arrangement promoted multiple internal reflections and scattering of electromagnetic waves.
Even at low filler loadings (below 5 wt%), properly aligned anisotropic nanostructures significantly improved EMI shielding, reducing the need for high filler content that could compromise mechanical flexibility. Increasing composite thickness led to a logarithmic improvement in SE, particularly in absorption-dominant shielding mechanisms. This study underscores the critical influence of nanofiller morphology and orientation on the electromagnetic shielding performance of polymer nanocomposites. The findings provide valuable insights into structure-property relationships, enabling the rational design of advanced EMI shielding materials. Optimized filler alignment can enhance shielding efficiency while minimizing material usage, benefiting lightweight and flexible electronics. Hybrid filler systems (e.g., combining CNTs and graphene) may offer synergistic effects, further improving broadband EMI attenuation.
Computational models developed in this work can guide the design of next-generation shielding materials for 5G, IoT, and aerospace applications.

Keywords: Maxwell polarization, composite polymeric materials, dielectric permeability, shielding, microwave field.

UDC: 537.871.5

MSC: 65N30