Graphene-Based Compact Ultrawideband Terahertz Plasmon Antenna With Characteristic Mode Analysis

An ultrawideband planar patch antenna based on graphene, operating in the terahertz (THz) frequency range, is presented in this work. The radiator is planned on a high-permittivity silicon (Si) dielectric material as substrate with a relative permittivity of 11.9, and its structure comprises three layers: a ground plane, a dielectric substrate, and a graphene patch. The silicon substrate and ground plane share identical dimensions of$30\times 35$$\mu $m2, while the radiating patch measures$25\times 25$$\mu $m2, offering a compact design suitable for THz integration. The proposed antenna exhibits ultrawideband (UWB) presentation, spreading an inclusive frequency range from 3.50 to 10 THz. This corresponds to a total bandwidth (BW) of 6.5 THz and a fractional BW of 96.29%. A deep reflection coefficient of −33.35 dB is observed at 7.831 THz, confirming excellent impedance matching. The radiator also exhibits the highest gain of 10.80 dBi and maintains high radiation efficiency across the band. To further validate the UWB, characteristic mode analysis (CMA) is conducted, providing deeper insight into the modal behavior of the structure. Given its high performance and compact size, the antenna is a suitable candidate for a wide range of THz applications.