Millimeter-wave FSS Improving Antenna Performance in 5G Mobile Terminal with Glass Cover Case

As the glass cover case becomes the dominated design in high-end smart phone, it commonly deteriorates antenna radiation performance due to its high dielectric constant. To solve this problem, a transmissive frequency selective surface (FSS) is proposed in this paper for antenna performance improvement at 5G millimeter-wave band. The proposed FSS based on metallic grid structure is designed on an ultra-thin dielectric layer, which can achieve a highly efficient passband of 21.45 - 30.56 GHz (35%) when attached to the glass cover case. Furthermore, the proposed FSS is co-designed with commercial cover case and a patch antenna in 5G mobile terminal and verified for its ability of improving beam coverage and gain of the antenna. It is also proved that the proposed FSS contributes to suppressing surface waves caused by the smartphone glass cover case.