Ultrathin Spoof Surface Plasmons Polaritons Antenna with Flat-Top Radiation Patterns

Ultrathin spoof surface plasmon polaritons (SSPP) exhibits attractive characteristics of both simple structure and easy control of its dispersion curve, which are utilized in this paper to synthesize flat-top radiation patterns. The proposed SSPP-based antenna radiates through +1
^st
space harmonic and the flat-top patterns are achieved by controlling the attenuation and phase constants at different positions of the antenna. Besides, a differential algorithm is also implemented to optimize the flat-top patterns. For validation, a prototype operating at 18.0 GHz is designed, fabricated and measured. Flat-top patterns are realized from 17.0 GHz to 18.0 GHz with a relative bandwidth of 5.7%. Compared with existing works, the proposed work has advantages of simpler structure and smaller size. Furthermore, the proposed structure can be extended to a planar one to synthesize two-dimensional flat-top patterns.