Dual-layer single-varactor driven reflectarray cell for broad-band beam-steering and frequency tunable applications

A dual-layer active reflectarray configuration is proposed for broad-band beam-steering and/or frequency tunable applications. A unit cell composed by two stacked fixed size rectangular patches, properly loaded with a single varactor diode, is designed to realize the dynamic phase tuning mechanism. The proposed approach offers wider bandwidths, with respect to the existing varactor-based reflectarray cells, and quite good frequency reconfigurability features, as demanded by several radar or satellite communication applications. A X-band reflectarray cell is fabricated and tested, to prove the effectiveness of the proposed approach, achieving a 318° phase agility within a measured frequency range of about 14.6% with respect to the central design frequency (i.e. 11 GHz). Wideband beam-steering reflectarray designs are demonstrated, showing 1dB-gain bandwidths equal to 9-10%.