Transmission Attenuation Evaluation of Noise Suppression Sheet for 5G and Beyond

To support the development of smart technology, such as the Internet of Things, smart devices, and smart manufacturing, 5G and beyond mobile communication systems will utilize higher frequencies. Accordingly, the number and types of network devices will increase, and how to suppress electromagnetic interference in such small wireless communication terminals will be an important issue. As one of the essential technologies, a noise suppression sheet needs to be developed to minimize electromagnetic interference problems in the new frequency bands. Here, we have developed a method to evaluate the transmission attenuation characteristics of noise suppression sheets up to 60 GHz, with reference to the IEC standard (IEC62333-2: below 6 GHz). To confirm its practicality, a systematic demonstration was performed by measuring commercially available noise suppression sheets under various conditions. The mechanism of the transmission attenuation effect in a wide frequency range, including an unexpected effect due to surface modes, is investigated based on material properties and electromagnetic simulations.