Reconfigurable Graphene-Based Metamaterial Polarization Converter for Terahertz Applications

Abstract This paper suggests a high gain polarization converter using a graphene-based metamaterial array. The graphene-based metamaterial polarization converter is a rectangular array that consists of 20 periodic unit-cell elements. Each graphene-based metamaterial unit-cell element consists of a rectangular patch with four triangular-shaped graphene parts at its four corners. The rectangular patch with the four graphene parts are placed over a rectangular substrate backed with a perfect electric conductor (PEC) and has a relative permittivity of εsub = 3.38. The metamaterial characteristics of the proposed graphene-based metamaterial unit-cell element are obtained over a wide range of frequencies of 0.7 THz ranging from 1.5 THz to 2.2 THz. The graphene-based metamaterial array is placed over a linear polarized slot antenna that operates at 1.8 THz with a maximum gain of 5.5 dBi. The linearly polarized wave that radiated from the slot antenna can be converted into a reconfigurable right-handed circular polarization (RHCP) or Left-handed circular polarization (LHCP) according to the biasing states of the graphene parts. Moreover, the operating -10 dB B.W of the slot antenna is increased to 22.2%, and the gain is enhanced to 8 dBi at the same operating frequency. A reconfigurable polarization conversion for the slot antenna can be obtained over a wide 3dB axial ratio (AR) B.W from 1.75 THz to 1.92 THz (20% 3dB B. W).