Leaky-Wave Radiations by Modulating Surface Impedance on Subwavelength Corrugated Metal Structures.

Ben Geng Cai,Yun Bo Li,Hui Feng Ma,Tie Jun Cui,Wei Xiang Jiang,Qiang Cheng

doi:10.1038/srep23974

Abstract

One-dimensional (1D) subwavelength corrugated metal structures has been described to support spoof surface plasmon polaritons (SPPs). Here we demonstrate that a periodically modulated 1D subwavelength corrugated metal structure can convert spoof SPPs to propagating waves. The structure is fed at the center through a slit with a connected waveguide on the input side. The subwavelength corrugated metal structure on the output surface is regarded as metasurface and modulated periodically to realize the leaky-wave radiation at the broadside. The surface impedance of the corrugated metal structure is modulated by using cosine function and triangle-wave function, respectively, to reach the radiation effect. Full wave simulations and measuremental results are presented to validate the proposed design.

Highlights

We apply the concept of surface impedance to the subwavelength corrugated metal structure, which originally supports the spoof surface plasmon polaritons (SPPs), and modulate the surface impedance using the cosine function and triangle-wave function, respectively, so that the modulated structures could radiate propagating waves as a periodic leaky-wave antenna
Like SPPs in the optical frequency, spoof SPPs is a kind of TM surface wave
The corrugated metal structure composed of subwavelength unit cells with the same size is quasi-uniform[35], and support slow surface waves only[21,22,23]

Summary

Introduction

We apply the concept of surface impedance to the subwavelength corrugated metal structure, which originally supports the spoof SPPs, and modulate the surface impedance using the cosine function and triangle-wave function, respectively, so that the modulated structures could radiate propagating waves as a periodic leaky-wave antenna. The energy is coupled from the slit to the subwavelength corrugated structure on the output surface of the metal to propagate spoof SPPs and radiate a narrow broadside beam with high directivity. The design process is analytical, and the experimental results agree well with the numerical simulations

Methods

Results

Conclusion