Electromagnetic wave shielding flexible films with near-zero reflection in the 5G frequency band

Abstract

The concern regarding the electromagnetic interference (EMI) issue with a short wavelength of the 5G frequency band has been increasing. Hence, EMI shielding materials with low reflection and high absorption capability are in high demand. However, current shielding materials are generally based on conductive materials and are reflection dominated. To address this problem, a novel EMI shielding flexible film with near-zero reflection has been proposed in this study. By integrating a magnetic absorbing composite layer and a tailored conductive grid, extremely low reflection and high shielding effectiveness were obtained. The conductive grid only transmits a specific resonant frequency of electromagnetic (EM) waves so that the EM waves are absorbed by the shielding film system with no reflection at the resonant frequency. The proposed film reports 0.1 dB reflection shielding effectiveness and 11.2 dB absorption shielding effectiveness at 26 GHz, which reflects only 0.2% of the incident waves while absorbing 92.2% of them. Another film with a higher shielding capability is also reported, which reflects 10.2% of the incident waves while shielding 99.7% of them. The remarkably low reflectance and thinness of the proposed films provide an important advancement toward the commercialization of EMI shielding materials for 5G communication applications.