Ultrathin switchable microwave filter based on graphene and slot array

The concept of ultrathin switchable microwave filter consisting of graphene sheet and slot array is presented. The proposed microwave filter shows a passband ranging from 14.4 GHz to 15.6 GHz, in which the transmission can be electrically controlled and decreased to lower than −17.5 dB at resonance achieving an off state, via electrostatic gating on the graphene stack. The analysis of transmission indicates that the current resonance of the filter is degraded due to surface resistance change of graphene layer, thus the reflectivity rises drastically. Furthermore, it is demonstrated that compared with the single-layer graphene sheet, the capability of tuning microwave transmission can be greatly improved using hybrid structures. The considerable switchable filter promises an active device in electromagnetic interference suppression and has an ultrathin thickness which can be easily integrated.