Metamaterial-Inspired Multi-port Tunable THz Antenna with Self-Multiplexing and MIMO Capability for 6G Wireless and Sensing Applications

Abstract

This work presents a novel THz antenna for 6G wireless and sensing applications, featuring multi-port frequency tunability with MIMO and self-multiplexing capabilities. The antenna consists of four fractal-shaped graphene patches arranged orthogonally on the top layer of a SiO₂ substrate, coupled with a CPW feed. Electrostatic potential applied to the graphene-loaded radiators enables diverse functionalities. A metamaterial structure, functioning as a band-reject filter, is integrated into the lower layer of the SiO₂ substrate to inhibit surface wave propagation. The proposed metamaterial structure uses Hilbert-shaped curves separated by high-impedance open-circuited stubs to improve isolation within the desired frequency band. The compact antenna (140 μm × 135 μm) offers a combined impedance bandwidth of 115% (3.98 to 14.5 THz) while utilizing frequency tunability and achieving over 25 dB isolation between radiators, with a peak gain of 7.7 dBi. The design operates in tunable four-port MIMO, self-duplexing two-port MIMO, and self-quadruplexing modes. MIMO parameters such as Envelope Correlation Coefficient (ECC), Total Active Reflection Coefficient (TARC), Diversity Gain (DG), and Channel Capacity Loss (CCL) are evaluated to confirm the antenna’s diversity performance. An equivalent circuit model (ECM) is also analyzed to explain the working principle and validate the results.