Low-profile high-efficiency bidirectional endfire antenna based on spoof surface plasmon polaritons

We proposed a simple method to realize a bidirectional endfire antenna based on spoof surface plasmon polaritons (SPPs). The bidirectional "8"-shaped radiation characteristic is achieved by the backfeeding method and the spoof SPPs structure, and the endfire radiation is obtained by loading parasitic strips at the ends of two dipoles. The overall dimension is 3.33? × 0.74λ × 0.015λ, showing low-profile characteristic. The proposed antenna is optimized to operate in the 5G WiFi frequency range. The realized gain is over 7 dBi, and the total radiation efficiency is over 85% from 5.3 to 5.7 GHz. The experimental results of S11 , normalized radiation pattern at different frequencies, the realized gain, and the radiation efficiency curves all agree well with the simulated ones. The proposed bidirectional endfire antenna will have potential applications in the spoof-SPPs-based communication system.