Characterization of Reconfigurable Reflectarray Elements using Scattering Measurement Technique

Reconfigurable reflectarrays and intelligent surfaces provide viable solutions to address joint communication and sensing requirements in next-generation wireless networks. Typically, the reconfigurable reflectarray consists of a large number of reflecting elements, or unit cells, whose reflection phase can be varied dynamically through electronic tuning. The functionality of the reconfigurable reflectarray depends on the tuning characteristics of its unit cells. Experimental characterization of the unit cells/elements can be accomplished using the classical waveguide simulator technique or near-field non-contact probing methods. However, the waveguide simulator technique application requires interconnects which may not be feasible to realize for many cell designs. On the other hand, the near-field probing methods, do not require interconnects but their accuracy could be affected by perturbation-induced errors. To improve upon the existing techniques, this paper devises a simple scattering technique to measure the reflection phase of the unit cells remotely. The measurement model will be developed and verified experimentally in the Ka-band (26.5 - 40 GHz). The measured reflection phase of a Ka-band waveguide unit cell using the proposed technique will be compared to the results obtained using the waveguide simulator technique. It will be shown that the proposed remote method provides comparable results to the waveguide simulator technique.