A design of 5G low-observable circularly polarized array antenna based on characteristic mode analysis and polarization conversion

Abstract This paper presents an ultra-wideband circularly polarized (CP) metasurface antenna for 5G applications, featuring high gain and low radar cross-section (RCS). The multiplexing of the CP antenna and the polarization converter (PC) is realized by using a co-design, which is based on the characteristic mode analysis method and PC principle. Subsequently, by optimizing the feeder network and implementing mirror-symmetric array arrangement, the operating bandwidth, the axial ratio bandwidth, and the gain performance are significantly improved simultaneously. The fabricated antenna operates at 5 GHz (fractional bandwidth of 47.2%), with a CP coverage ratio 91.1%. It maintains a consistent gain above 7 dBi across the entire band and exceeds 10 dBi over 70% of the bandwidth, while exhibiting stable radiation patterns and excellent directivity. Notably, the antenna achieves a 10 dB RCS reduction across the entire operational bandwidth, enabling its wide application in 5G communications.