A high gain circularly polarized 2 × 2 antenna array based on the spoof surface plasmon polariton and spoof localized surface plasmon

Abstract

Two circularly polarized (CP) 2 × 2 array antennas based on the spoof surface plasmon polariton (SPP) and spoof localized surface plasmon (LSP) are proposed. The antenna I is fed by a feed network to increase the axial-ratio (AR) bandwidth. The spoof SPP and spoof LSP are introduced to increase the gain through energy localization, and the structure can suppress the cross-polarization to a certain extent and obtain a wider axial-ratio beamwidth. In addition, the electromagnetic band gap (EBG) is used to suppress surface waves to further increase the gain. The size of antenna I is 1.27λg × 1.27λg × 0.18λg. The impedance bandwidth and the AR bandwidth of antenna I are 72% (3.15–6.75 GHz) and 55% (3.97–6.72 GHz), respectively, and the peak gain is 11.11 dBi. The antenna II optimizes the distance between the two substrates according to antenna I to further increase the gain.