Graphene-based series-fed plasmonic antenna array optimised with metaheuristic algorithm for 6G THz communications

Abstract

This paper presents the modelling and optimisation of a compact series-fed plasmonic antenna array operating in the terahertz (THz) frequency range from 1 THz to 1.8 THz, suitable for 6 G communication applications. The proposed antenna is designed using graphene over a polyimide substrate, taking advantage of graphene’s tunable plasmonic properties and the substrate’s mechanical flexibility. The antenna elements are configured using a single resonator structure, comprising a rhombus-shaped resonator and an octagonal resonator, connected via a central cross dipole to ensure broadband impedance matching and stable radiation characteristics. Firefly Algorithm (FFA) is employed for optimisation, improving the antenna’s performance parameters. A series-fed configuration is adopted to achieve compact integration with directional gain. The design is extended to a two-element multiple-input multiple-output (MIMO) system for improved data throughput. The array occupies a physical size of 125 × 28 µm, corresponding to 0.417λ × 0.093λ at 1 THz, and achieves a fractional bandwidth of 55.5 %. The realized gain of the antenna is greater than 7.8 dBi and a total efficiency above 80 % across the entire operational band. Key MIMO performance indicators—envelope correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), and channel capacity loss (CCL)—are evaluated and presented, demonstrating strong isolation and diversity performance. Simulation results confirm that the optimized antenna array, using FFA, is a promising candidate for integration into compact THz front-end modules for 6 G communication systems.