Shielding Effectiveness Calculation of Anisotropic Carbon Fiber Honeycomb Transparent Structures Based on LOD-FDTD Method

Aiming at the theoretical calculation of electromagnetic shielding effectiveness (SE) for carbon fiber honeycomb structures used in transparent stealth windows, this paper proposes a multi-scale analysis method based on equivalent circuit modeling and numerical simulation. First, an equivalent impedance network of the carbon fiber honeycomb structure is constructed based on the Keller model and the symmetry of the honeycomb unit cell, from which the equivalent electromagnetic tensor is derived. Next, an anisotropic algorithm based on Leapfrog Locally One-Dimensional Finite-Difference Time-Domain (LOD-FDTD) is developed, enabling full-wave electromagnetic simulation of honeycomb structures under oblique incidence. Finally, experimental results validate the accuracy of the theoretical model. The results indicate that the carbon fiber honeycomb structure achieves a shielding effectiveness of up to 42.3 dB and an optical transmittance exceeding $83 \%$ in the $1-18 \mathrm{GHz}$ frequency band. In addition, this study provides a theoretical basis for designing transparent stealth windows using carbon fiber honeycomb structures. It offers new insights for metasurface design under multiphysics coupling, thereby possessing dual value in military protection and civilian anti-interference applications.