Characteristic Modes-Inspired Polarization Twisting Metasurface Element for 1-bit Folded Reflectarray.

A 1-bit folded reflectarray (FRA) based on characteristic modes-inspired polarization twisting metasurface element is proposed. The element is inspired by a 2×2 patch-based metasurface where a corner patch is removed and a pair of the patch is connected to break the symmetry for polarization twist and reduce the number of switches with the assistance of the characteristic mode analysis. On this basis, only two switches are required in each element for 1-bit phase encoding. To verify the proposed metasurface element, two 1-bit FRA in the Ka-band with beam directions of 0° and 60° are designed and fabricated where the metal stubs/open circuits are employed instead of real switches. The measured peak gains reach 27.4 dBi at 30 GHz with an aperture efficiency of 21.2% and a 3 dB bandwidth of 16.2%. This FRA exhibits good beam scanning characteristics with high gain and wide fractional bandwidth, which shows great potential in the application of low-cost electronically beam-steerable antennas. [ABSTRACT FROM AUTHOR]