Broadband Low-AR Dual-CP High-Order-Mode Back-Cavity Slot Antenna

In this paper, a broadband, low-axial-ratio (low-AR), single-dielectric-layer dual circularly polarized (dual-CP) antenna array based on high-order-mode back-cavity slot antenna (HOM-BSA) is proposed for fifth-generation (5G) applications. Two broadband single-CP arrays with low-AR are obtained by sequential rotation based on L-type and rectangular-type (Rect-type) HOM-BSA element, respectively. Furthermore, through splicing geometric structure, the above two single-CP arrays are combined to obtain a single-dielectric-layer dual-CP array. The simulated results show that the −10 dB impedance bandwidth of the dual-CP array can fully cover 5G communication bands n257, n258 and n261 (19.54%, 24.25-29.5 GHz). Within the impedance bandwidth, the AR of left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) are less than 0.02 dB and 0.03 dB, respectively, which means that the purity of circular polarization is very high.