A Reconfigurable Reflectarray Structure Based on Metamaterial Unit Cells for 5G Applications

This article presents the design and analysis of the reconfigurable reflectarray structure based on metamaterials for Sub-6 GHz 5G applications. The proposed reflectarray structure is printed on a 1 mm-thick FR4 dielectric substrate with a total size of 180 × 180 mm2. The reflectarray consists of 144 unit cells, each with dimensions of 15 × 15 × 1 mm3. The unit cell design is a single layer based on multi-concentric square rings. A single layer is used to achieve a negative constitutive parameter (-εr or -μr); multiple rings of different sizes provide a wide reflection bandwidth to improve the performance of the reflective surface. Dual bands of reflection were observed. The first band of reflection is 2.6 GHz, 1.98-4.6 GHz, and the second band is 1.71 GHz, 7.41-9.1 GHz. Two PIN diodes are used in each unit cell of the reflectarray structure for reconfigurable behavior achievement. Depending on the diode states, the phase distribution across the proposed reflectarray structure changes, and the incident waves are reflected at different angles. This work conducted a comprehensive analysis of S-parameters, constitutive parameters, and refractive index, based on full-wave analysis. The CST Microwave Studio software package was used to design and analyze the proposed design structures. A good agreement was observed between the measurement results and those from the simulation.