Design of tunable THz dielectric resonator antenna with cross-slot for circular polarization

A novel dual band tunable terahertz (THz) circularly polarized dielectric resonator antenna (CPDRA) is designed and numerically studied. Hybrid Silicon-Graphene materials are employed as radiator with cross-slot shaped aperture coupled feed, enabling tunable linearly and circularly polarized radiation. Silicon is a good material as dielectric resonator with its operation in the THz regime due to lack of absorption, cheaper to grow and machine. Cross shaped slots of appropriate dimensions are engraved in the centre of the ground plane to split the fundamental mode of the rectangular DR into two near degenerate orthogonal modes having quadrature phase difference. As a result, circular polarization is obtained in the upper passband. Introducing cross slot also helped to improve the impedance matching and dual band operation is achieved with linearly polarized response in lower band and circularly polarized response in the upper band. By adjusting the chemical potential of graphene, frequency tunability in the both the operating bands is obtained, without changing the physical geometry of the antenna. The proposed antenna operates with \(10\;{\text{dB}}\) $10\text{dB}$ impedance bandwidth of \(4.24{\text{\% }}\) $4.24\text{\%}$ (2.31–2.41 THz) and \(12.1{\text{\% }}\) $12.1\text{\%}$ (3.11–3.51 THz) and \(3\;{\text{dB}}\) $3\text{dB}$ axial ratio bandwidth of \(3.54{\text{\% }}\) $3.54\text{\%}$ (3.33–3.45 THz). The antenna parameters are calculated and gain of \(6.11 \;{\text{dBi}}\) $6.11\text{dBi}$ and \(5.8 \;{\text{dBiC}}\) $5.8\text{dBiC}$ in lower and upper band, respectively and radiation efficiency of \(96.5{\text{\% }}\) $96.5\text{\%}$ in both operating bands is obtained. This hybrid radiator-based THz CPDRA shows great potential in the development of tunable THz devices and could pave a path for new researchers.