Design of optically transparent film with high electromagnetic shielding effectiveness

The proliferation of electronic and wireless systems has elevated electromagnetic interference (EMI) to a critical challenge in modern photoelectric applications. High-performance EMI shielding solutions for optical windows in aircraft, spacecraft, and electronic displays demand simultaneous achievement of superior shielding effectiveness (SE) and optical transparency. This study presents two innovative transparent shielding film configurations: a double-layer nested ring metamaterial and a bio-inspired honeycomb grid structure. By optimizing the unit cell period and wire filling ratio, it can realize high SE and balance high optical transmittance. Full-wave simulations demonstrate that the single-layer nested ring metallic mesh achieves a SE exceeding 28.8 dB below 40 GHz, with a theoretical transmittance of 88.3%. For the double-layer nested ring metallic mesh, the SE exceeds 45.7 dB below 40 GHz, with a theoretical transmittance of 78%. Another approach involves a transparent EMI shielding film based on double-layer hexagonal grid structure. The full-wave simulation SE at 18 GHz is 54 dB, the measured SE at 18 GHz is 46 dB, and the transmittance is 80.3%. The experimental and simulation curves are in good agreement. The proposed schemes hold promising prospects in the broadband high-shielding applications of aerospace optoelectronic systems.