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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.

The plasmonic waveguide made of uniform corrugated metallic strip can support and guide spoof surface plasmon polaritons (SSPPs) with high confinements. Here, we propose periodically-modulated plasmonic waveguide composed of non-uniform corrugated metallic strip to convert SSPPs to radiating waves, in which the main beam of radiations can steer continuously as the frequency changes. To increase the radiation efficiency of the periodically-modulated plasmonic waveguide at the broadside, an asymmetrical plasmonic waveguide is further presented to reduce the reflections and realize continuous leaky-wave scanning. Both numerical simulations and experimental results show that the radiation efficiency can be improved greatly and the main beam of leaky-wave radiations can steer from the backward quadrant to the forward quadrant, passing through the broadside direction, which generally is difficult to be realized by the common leaky-wave antennas.

Spoof surface plasmon polaritons(SSPPs) are kind of highly confined surface waves, which can be supported by corrugated metallic strips at microwave frequencies. In this letter, an omnidirectional antenna utilizing periodically modulated double-edge corrugated metallic strips has been proposed, in which the depths of grooves are designed periodically to modulate wave number. The designed SSPPs antenna radiates at 55° from z-axis at 9.3GHz with the directivity of 12.2dBi. Simulation results show that the radiation beam is omnidirectional in azimuth plane and frequency steerable in elevation plane.

We propose a kind of anisotropic planar metasurface, which has capacity to manipulate the orthogonally-polarized electromagnetic waves independently in the reflection mode. The metasurface is composed of orthogonally I-shaped structures and a metal-grounded plane spaced by a dielectric isolator, with the thickness of about 1/15 wavelength. The normally incident linear-polarized waves will be totally reflected by the metal plane, but the reflected phases of x- and y-polarized waves can be controlled independently by the orthogonally I-shaped structures. Based on this principle, we design four functional devices using the anisotropic metasurfaces to realize polarization beam splitting, beam deflection and linear-to-circular polarization conversion with a deflection angle, respectively. Good performances have been observed from both simulation and measurement results, which show good capacity of the anisotropic metasurfaces to manipulate the x- and y-polarized reflected waves independently.

Broadband circular and linear polarization conversions have been proposed in the paper by using thin birefringent reflective metasurfaces, which are composed of two orthogonal I-shaped structures placed on the top of a printed circuit broad with grounded plane on the bottom. We show that the metasurface manipulates the reflective phases of two orthogonal linearly-polarized waves independently by changing the dimensions of I-shaped structure. Hence, the polarization states of a linearly-polarized incident wave with normal incidence can be manipulated as desired after reflected by the anisotropic metasurface. Two polarization conversions have been presented by using such thin birefringent reflective metasurfaces: from linearly-polarized wave to circularly-polarized wave, and from linearly-polarized wave to cross-polarized wave. The metasurfaces work at microwave frequency, and the axial ratio better than 1dB is achieved within fractional bandwidth of 15% for circular polarization. Numerical and experiment results demonstrate good polarization conversions in a broad frequency band, which have excellent agreements with the theoretical calculations.