A novel stopband frequency-selective surface (FSS) made of high-conductivity graphene assemble films (HCGFs) for reducing the mutual coupling between dielectric resonator antennas (DRAs) is investigated and presented. The FSS is a "Hamburg" structure consisting of a two-layer HCGF and a one-layer dielectric substrate. A laser-engraving technology is applied to fabricate the FSS. The proposed improved Jerusalem cross FSS, compared with cross FSS and Jerusalem cross FSS, can effectively reduce the size of the unit cell by 88.89%. Moreover, the FSS, composing of 2 × 10-unit cells along the E-plane, is proposed and embedded between two DRAs, which nearly has no effect on the reflection coefficient of the antenna. However, the mutual coupling is reduced by more than 7 dB on average (7.16 dB at 3.4 GHz, 7.42 dB at 3.5 GHz, 7.71 dB at 3.6 GHz) with the FSS. The patterns of the antenna are also measured. Therefore, it is suggested that the proposed FSS is a good candidate to reduce mutual coupling in the multiple-input-multiple-output (MIMO) antenna system for 5G communication.
Keywords: dielectric resonator antenna array; frequency-selective surface; high-conductivity graphene films; mutual coupling reduction.