Tunable Graphene Reflective Cells for THz Reflectarrays and Generalized Law of Reflection

TL;DR

This paper introduces a tunable graphene-based reflective cell for THz reflectarrays, enabling dynamic phase control, miniaturization, and implementation of the generalized law of reflection, with validated circuit models and promising performance metrics.

Contribution

It presents a novel graphene-based reflective cell design with a wide phase tuning range and accurate circuit modeling for THz applications.

Findings

Achieved 300-degree phase tuning range.

Demonstrated effective control of reflected wave phase.

Validated circuit model accurately predicts element response.

Abstract

A tunable graphene-based reflective cell operating at THz is proposed for use in reconfigurable-beam reflectarrays, or similarly to implement the so-called generalized law of reflection. The change in the complex conductivity of graphene when biased by an electric field allows controlling the phase of the reflected field at each element of the array. Additionally, the slow wave propagation supported by graphene drastically reduces the dimensions of the cell, which allows smaller inter-element spacing hence better array performance. An elementary cell is optimized and its scattering parameters computed, demonstrating a dynamic phase range of 300 degrees and good loss figure for realistic chemical potential variations. Finally, a circuit model is proposed and shown to very accurately predict the element response.