Wide-angle transmitarray metasurface retroreflector

Due to its important academic values and widespread applications in civil and military domains, metasurface-assisted wide-angle planar retro-reflectors have received much attentions across from optics to microwave band recently. Compared to conventional retro-reflectors such as corner reflectors or Luneburg lens reflectors, metasurface reflector have many advantages such as low-profile, easy fabrications, conformal design and versatile backscattering enhancement control, etc. However, it is a great challenge to design a wide-angle metasurface retro-reflector which can outperform traditional ones with a reduced device thickness. Inspired by recent progresses on high-efficiency transmit-array antenna-assisted flat retro-reflectors, we here provide a complete performance comparison between this kind of four-layer metasurface-assisted retroreflector and conventional reflectors (corner reflectors and Luneburg lens reflectors) in terms of RCS backscattering level and working angular range for the same effective area and operation frequency. According to our measurement results, the 3dB RCS working angular range of metasurface retroreflector is between corner reflector and Luneburg lens reflector while the peak RCS value in the middle is much lower than these traditional retro-reflectors. The reason for this degraded RCS level is also discussed and analyzed. This work is meaningful to judge the device quality of metasurface-based retroreflectors compared to conventional ones and can provide a deep understanding of its working mechanism of this kind of flat retro-reflectors.