Frequency reconfigurable antipodal Vivaldi 2-port antenna based on graphene for terahertz communications

Abstract

A graphene-based two ports antipodal Vivaldi antenna with improved gain for THz applications is introduced. The single antenna is composed of an antipodal Vivaldi antenna with a graphene radiator on the top and copper ground plane on the back with a total size equal to 108 µm × 84 µm to achieve reconfigurable performance from 3 to 4.5 THz. The reconfigurability is validated by changing the external DC Volt which in turn changes the graphene chemical potential and then changes the operating frequency. As well, to enhance the antenna gain, frequency selective surfaces (FSS) with a metallic patch are utilized to enhance the antenna gain. The FSS performance is investigated and optimized using a finite integral technique (FIT) software to achieve a reflective feature with band rejection from 2 up to 5 THz within the operating bands of the suggested antenna. The FSS is inserted below the MIMO antenna to reflect the antenna radiation and then enhance the antenna gain. The antenna gain is increased from 6 dB (single antenna without FSS) to 10.8 dB (with FSS) at 3.4 THz. The MIMO antenna is operated from 3.2 to 4.45 THz with S11 ≤ − 10 dB, isolation ˃ 20, gain from 8 to 10.8 dB, and efficiency higher than 80%. Finally, the MIMO parameters outcomes achieved good values which suggested the antenna to be employed in IoT THz applications.