Leaky wave antenna with backfire to endfire beam-scanning capability based on even mode spoof surface plasmon polaritons

In this paper, a leaky wave antenna (LWA) based on even mode excited spoof surface plasmon polaritons (SSPPs) is proposed. The LWA can radiate beams from backfire to endfire as the frequency increases. The proposed LWA is asymmetrically modulated by the method of sinusoidal modulation of the reactance surface at two sides of the SSPP structure, which brings a phase difference between two sides of the antenna. The phase difference produces the field component that radiates the beam in the backfire or endfire direction. In this way, the full-angle beam scanning is realized. Moreover, to reduce the open-stop band effect, an improved LWA with multiperiod modulation and asymmetric units is proposed. The simulated results indicate that the radiation beam steers from backfire to endfire. A prototype of the proposed LWAs is fabricated and measured. The measured results agree well with the simulated ones.