Recent advances in graphene-based terahertz microstrip antennas: A technical review of substrate choices and emerging challenges

Abstract

The Terahertz (THz) spectrum, bridging the microwave and infrared regions, holds immense promise for high-speed communications, imaging, and sensing. However, efficient THz antenna design remains a critical challenge due to issues like narrow bandwidth and signal attenuation. This review focuses on recent advances in graphene based microstrip antennas for THz applications, with a particular emphasis on substrate selection and associated design challenges. Graphene’s exceptional electrical conductivity, high electron mobility, and tunable surface impedance make it an ideal candidate for reconfigurable and miniaturized THz antennas. The study categorizes and compares both linearly and circularly polarized THz antenna designs, highlighting the impact of conductive and substrate materials on impedance, bandwidth, gain, and polarization characteristics. Polyimide and SiO₂ emerge as leading substrate materials due to their low loss, thermal stability, and compatibility with graphene. Circularly polarized antennas demonstrate promising axial ratio bandwidths and gains when employing graphene polyimide and graphene-SiO₂ combinations. Despite notable advancements, challenges such as limited gain-bandwidth tradeoffs, polarization purity, and fabrication complexity remain. The review concludes by identifying future research directions, including substrate engineering, reconfigurable architectures, and dual polarization techniques, to meet the growing demands of next-generation THz communication systems.