Abstract
A wide-band and high gain circularly polarized (CP) graphene-based reflectarray operating in the THz regime is proposed and theoretically investigated in this paper. The proposed reflectarray consists of a THz CP source and several graphene-based unit-cells. Taking advantages of the Pancharatnam Berry (PB) phase principle, the graphene-based unit-cell is capable of realizing a tunable phase range of 360° in a wide-band (1.4–1.7 THz) by unit-cell rotating, overcoming the restriction of intrinsic narrow-band resonance in graphene. Therefore, this graphene-based unit-cell exhibits superior bandwidth and phase tunability to its previous counterparts. To demonstrate this, a wide-band (1.4–1.7 THz) focusing metasurface based on the proposed unit-cell that exhibits excellent focusing effect was designed. Then, according to the reversibility of the optical path, a CP reflectarray was realized by placing a wide-band CP THz source at the focal point of the metasurface. Numerical simulation demonstrates that this reflectarray can achieve a stable high gain up to 15 dBic and an axial ratio around 2.1 dB over the 1.4–1.7 THz band. The good radiation performance of the proposed CP reflectarray, as demonstrated, underlines its suitability for the THz communication applications. Moreover, the design principle of this graphene-based reflectarray with a full 360° phase range tunable unit-cells provides a new pathway to design high-performance CP reflectarray in the THz regime.
Highlights
Terahertz (THz) science and technology that is undergoing an unprecedented rapid development has attracted considerable attention in the scientific community
In terms of communication applications, the THz communication system is promising as it has a sufficient bandwidth that is capable of handling high data rate up to
We propose a graphene-based wide-band circularly polarized (CP) reflectarray operating in the THz regime
Summary
Terahertz (THz) science and technology that is undergoing an unprecedented rapid development has attracted considerable attention in the scientific community. It seems that reflectarrays can be chosen as a competitive candidate for high gain and CP THz applications Most of these reflectarrays rely on judiciously designed metallic structures, which cannot scale to the THz frequencies because of the prominent skin effect of the conventional metal.The ohm loss of the metallic will immensely affect the array gain and radiation efficiency. Due to the intrinsic resonant properties and finite losses (such asa damped oscillator) of the graphene-based material, only a narrow band phase tunable range of 300◦ has been presented [20,42,43,44], which restrict their applications in scenarios where high radiation performances are required.
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