Wideband circularly polarized array antenna based on sequential phase feeding metasurfaces for 5G (sub-6G) applications

In this paper, a broadband circularly polarized array antenna is presented, which consists of four loop slot antennas based on metasurfaces. The antenna element is a loop slot antenna fed by a microstrip line. Cross slots are added to the loop slot to improve the antenna bandwidth, and four corner-cut square metasurfaces are loaded above it, thus generating circularly polarized radiation. The antenna adopts a sequential phase (SP) feed network to realize broadband characteristics. The antenna has been fabricated and experimented. The overall size of the antenna is 78 x 78 x 10.1 mm(3) (approximately 1.22 lambda(0 )x 1.22 lambda(0 )x 0.15 lambda(0)), the antenna array has a measured |S-11| < -10 dB bandwidth of 3.6-6.2 GHz (53.1%) and a 3-dB axial ratio bandwidth of 3.7-4.8 GHz (28.32%). Furthermore, the antenna also has radiation with a peak gain of 5.5 dBi.