High Gain and High-Efficiency Millimeter-Wave Antenna Based on Spoof Surface Plasmon Polaritons

Planar spoof surface plasmonic polaritons (SPPs) have attracted much attention due to the features of the subwavelength confinement and low transmission loss. The latter feature is highly desired in millimeter wave (mm-wave) and terahertz band. In this communication, a novel method is proposed to convert bounded spoof SPPs mode to radiation mode. An equivalent radiating aperture is formed by gradually decreasing the grooves of an odd-mode plasmonic structure. The mechanism of SPPs wave radiating out through the aperture is clarified by referring to a horn antenna. Furthermore, a spoof SPPs traveling-wave antenna prototype is designed and measured to validate the concept. Measured results show that the antenna has a high gain (~15 dB) and high radiating efficiency (~90%) at the mm-wave frequency. The measured narrow beamwidth in endfire direction indicates that it can be used to construct switched-beam arrays for 5G applications.