A Circularly Polarized Antenna with Low Sidelobe Based on Spoof Surface Plasmon Polariton

A circularly polarized leaky wave antenna based on spoof surface plasmon polariton (SSPP) with sidelobe suppression design is proposed. By arranging a series of elliptical patch arrays and coupling the energy on the transmission line (TL), the slow wave mode originally bounded on the SSPP TL is converted to the space wave mode of radiation. The variation of frequency leads to the change of transmission phase on the TL, and then forms the scanning of beam. The shape and the position of patches determine the formation of CP beams. The multi-layer spatial layout enables the patch array to achieve the effect of low sidelobe. In the simulation results, the antenna can realize right-handed CP wave scanning from -19 degrees to 16 degrees in 11.8-14.0GHz, and the radiation efficiency is mostly around 90%. The sidelobe levels in the bandwidth are less than -16dB, axial ratios (ARs) are less than 3dB, and the gain is also higher than 10dBi. Its excellent characteristics make it have great application potential in wireless communication system.