Low sidelobe leaky-wave antenna based on spoof plasmonic waveguide
Spoof surface plasmon polaritons (SSPPs) are highly confined surface electromagnetic waves, which can be supported by subwavelength periodic metal structure. According to the theory of sinusoidally modulated reactance surface (SMRS), SSPPs could be transformed into directional leaky-wave radiation through wavenumber modulation. In this paper, we propose a method to suppress the sidelobe level of the plasmonic leaky-wave antenna by designing a non-uniform sinusoidally modulated plasmonic waveguide composed of double edge corrugated metallic strip. A low sidelobe plasmonic leaky-wave antenna has been designed by controlling the amplitude of SSPPs to be a taper distribution on the aperture of plasmonic waveguide. Furthermore, an unsymmetrical SSPPs waveguide is designed by staggering corrugated grooves on two sides with μ/4 offset to increase the radiation efficiency at broadside. Both numerical simulations and experimental results have good agreements, which show that this method is effective to reduce the sidelobe of leaky-wave radiation by using non-uniform sinusoidally modulation of the plasmonic waveguide.