This paper presents a programmable hybrid copper–graphene metasurface antenna for simultaneous steerable beam generation in the terahertz band, targeting wide‑angle, low‑voltage multi‑beam operation for emerging 6G wireless systems. The metasurface consists of a 20 × 20 array of E‑shaped unit cells designed to operate at 2.35 THz, with overall dimensions of 800 × 800 × 10 μm³. Each unit cell integrates an E‑shaped copper resonator with tunable graphene arms on a quartz substrate backed by a polysilicon ground plane and a thin HfO2 gate dielectric, enabling low‑voltage electronic control. The design process begins with parametric optimization of the hybrid unit-cell geometry to maximize phase tunability at 2.35 THz, followed by selection of an 8 nm HfO2 gate dielectric to achieve practical low-voltage operation, and concludes with array-level phase distribution synthesis for beam steering and multi-beam generation. Comprehensive parametric study is conducted on the effect of graphene chemical potential (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\:{{\upmu\:}}_{\text{c}}\)</EquationSource> </InlineEquation>), relaxation time (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\:{\uptau\:}\)</EquationSource> </InlineEquation>), and temperature (<InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\:\text{T}\)</EquationSource> </InlineEquation>) on material response characteristics for phase tuning perforFmance. At <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\:{\uptau\:}=3\:\text{p}\text{s}\:\)</EquationSource> </InlineEquation>and <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\:\text{T}=300\:\text{K}\)</EquationSource> </InlineEquation>, variation of <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\:{{\upmu\:}}_{\text{c}}\)</EquationSource> </InlineEquation> from 0.22 eV to 1.0 eV yields reflection magnitude ranging from − 10 dB to − 0.1 dB with 355° phase coverage. The metasurface supports beam steering over elevation angles up to <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(\:\pm\:6{8}^{\text{o}}\)</EquationSource> </InlineEquation> with full <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(\:360^\circ\:\)</EquationSource> </InlineEquation> azimuthal coverage, achieving a maximum gain of 17.4 dB and maintaining acceptable sidelobe levels and beamwidth across the steering range. In addition, simultaneous dual, triple, and quadruple beams radiation patterns are realized using a superposition‑based phase synthesis, enabling independently steerable directive beams without aperture partitioning. Compared with previously reported terahertz graphene metasurfaces operating at lower frequencies with narrower steering ranges (typically ±45–60°) and single/dual-beam capabilities, the proposed design offers clear advantages in steering range, multi-beam generation (up to four beams), and biasing practicality (0.2–4.3 V operation), making it well suited as a reconfigurable intelligent surface for 6G terahertz wireless communication and sensing.

A programmable hybrid metal-graphene metasurface antenna for wide-angle multi-beam steering at terahertz frequencies

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2026年4月22日

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Abdelkarim S. Elhenawy,
Ahmed Allam,
Haruichi Kanaya,
Adel B. Abdel-Rahman

摘要

This paper presents a programmable hybrid copper–graphene metasurface antenna for simultaneous steerable beam generation in the terahertz band, targeting wide‑angle, low‑voltage multi‑beam operation for emerging 6G wireless systems. The metasurface consists of a 20 × 20 array of E‑shaped unit cells designed to operate at 2.35 THz, with overall dimensions of 800 × 800 × 10 μm³. Each unit cell integrates an E‑shaped copper resonator with tunable graphene arms on a quartz substrate backed by a polysilicon ground plane and a thin HfO₂ gate dielectric, enabling low‑voltage electronic control. The design process begins with parametric optimization of the hybrid unit-cell geometry to maximize phase tunability at 2.35 THz, followed by selection of an 8 nm HfO₂ gate dielectric to achieve practical low-voltage operation, and concludes with array-level phase distribution synthesis for beam steering and multi-beam generation. Comprehensive parametric study is conducted on the effect of graphene chemical potential ( \(\:{{\upmu\:}}_{\text{c}}\) ), relaxation time ( \(\:{\uptau\:}\) ), and temperature ( \(\:\text{T}\) ) on material response characteristics for phase tuning perforFmance. At \(\:{\uptau\:}=3\:\text{p}\text{s}\:\) and \(\:\text{T}=300\:\text{K}\) , variation of \(\:{{\upmu\:}}_{\text{c}}\) from 0.22 eV to 1.0 eV yields reflection magnitude ranging from − 10 dB to − 0.1 dB with 355° phase coverage. The metasurface supports beam steering over elevation angles up to \(\:\pm\:6{8}^{\text{o}}\) with full \(\:360^\circ\:\) azimuthal coverage, achieving a maximum gain of 17.4 dB and maintaining acceptable sidelobe levels and beamwidth across the steering range. In addition, simultaneous dual, triple, and quadruple beams radiation patterns are realized using a superposition‑based phase synthesis, enabling independently steerable directive beams without aperture partitioning. Compared with previously reported terahertz graphene metasurfaces operating at lower frequencies with narrower steering ranges (typically ±45–60°) and single/dual-beam capabilities, the proposed design offers clear advantages in steering range, multi-beam generation (up to four beams), and biasing practicality (0.2–4.3 V operation), making it well suited as a reconfigurable intelligent surface for 6G terahertz wireless communication and sensing.