Design and Experimental Characterization of a Tunable Hexagonal Unit Cell for 5G Reconfigurable Intelligent Surfaces at 2.5 GHz
Reis, J. R.
;
Oliveira, T.O.
; Madail, S.
; Salgado, J.
;
Caldeirinha, R. F. S.
Design and Experimental Characterization of a Tunable Hexagonal Unit Cell for 5G Reconfigurable Intelligent Surfaces at 2.5 GHz, Proc European Conference on Antennas and Propagation - EuCap, Dublin, Ireland, Vol. , pp. - , April, 2026.
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Abstract
In this paper, an electronically tunable hexagonal- slotted unit cell with continuous phase control, designed for a reconfigurable intelligent surface (RIS) operating within the mid-band 5G NR frequency range (n41, 2.496 – 2.69 GHz), is presented. The unit cell features a hexagonal geometry with overall dimensions of 46 × 46 mm2 and incorporates a BB833 varactor diode. This work details the design, simulation, and experimental validation of the proposed reconfigurable unit cell for potential use in RIS applications. The unit cell demonstrates relatively good amplitude and phase control, achieving a measured phase tuning range up to 310◦, in strong agreement with simulation results. When implemented in a RIS, the proposed design attains aperture efficiencies of 60.3% (RIS = 73.18 dB(mm2)) for reflection at 20º in azimuth and 55.5% (RIS = 71.05 dB(mm2)) for reflection at 40º in elevation. These results confirm the high reconfigurability and excellent performance of the proposed unit cell, paving the way for practical RIS implementations.
