Nonperiodic Metasurfaces for Retroreflection of TE/TM and Circularly Polarized Waves

In this article, we propose nonperiodic metasurfaces used for retroreflection of oblique incident wave with linear polarization (TE/TM) and circular polarization (CP). For CP wave, both handedness reversal and handedness preservation cases are demonstrated. The proposed metasurfaces consist of nonperiodic group cells optimized by genetic algorithm for desired scattered power patterns. Each group cell includes several locally periodic elements that are characterized by their reflection phase response under TE/TM or CP illumination. The proposed metasurfaces for retroflection have achieved reduced sidelobe level and suppressed specular beam and are verified by both full wave simulation and measurement at 10 GHz. This nonperiodic metasurface design method offers fast implementation for retroreflection of any plane wave with easy planar fabrication and can be easily scaled to millimeter-wave, THz, and optical regimes.