A Compact Left-Handed Circularly Polarized Planar Antenna for Terahertz Applications

This paper presents a compact left-hand circularly polarized planar antenna for terahertz applications. The antenna features a graphene-based structure built on an RT/duroid® 5880 substrate, optimized for THz band operation. Initially, the antenna exhibited linear polarization. To achieve circular polarization, the graphene-based radiating element was modified through an optimization process that introduced truncated corners, flower and circular slots. These steps ensure optimal resonance at 2.45 THz with improved reflection loss and axial ratio characteristics. The resulting LHCP antenna, with compact dimensions of 54 × 52 × 1.57 µm3, exhibits superior performance, achieving a 10 dB return loss bandwidth of 100 GHz (2.4–2.5 THz), a 3 dB axial ratio bandwidth of 161 GHz (2.345–2.506 THz), a peak gain of 7 dB, and a peak radiation efficiency of 95%. These characteristics underscore its strong potential for high-performance wireless communication within the THz band (2.4–2.5 THz).