Polarization-insensitive unidirectional spoof surface plasmon polaritons coupling by gradient metasurface
Shi Hong-yu1, Zhang An-xue1, 2, †, , Chen Jian-zhong1, Wang Jia-fu3, Xia Song4, Xu Zhuo4
       

The normalized measured radiation patterns: (a) under parallel polarized incidence, (b) under normal polarized incidence.