High-efficiency circularly polarised leaky-wave antenna fed by spoof surface plasmon polaritons

A circularly polarised (CP) periodic leaky-wave antenna excited by spoof surface plasmon polaritons (SPPs) is proposed. It is based on an SPP transmission line loaded by periodic rectangular patches on both sides with 90 ∘ phase shift, which converts the SPPs mode to CP propagating waves in the air. Due to the dispersion nature of SPPs waveguide, this leaky-wave antenna exhibits a beam scanning feature. Both simulated and measured results demonstrate that the proposed antenna has an impedance bandwidth of 33% for | S 11 | < − 10 dB and a 3 dB axial ratio bandwidth of 15%. The average gain and radiation efficiency are about 10 dBic and 87% from 5.5 to 6.4 GHz, respectively.