UWB, compact, dual-polarized antenna designed by tightly coupling technology

Abstract

This study explores tightly coupling technology applied in the design of an ultra-wideband (UWB), compact, dual-polarized antenna. The proposed design utilizes tightly coupling effects to achieve UWB performance, with a notable feature being its double-dipole topology. This topology significantly reduces the difficulty of impedance matching across the ultra-wide band. To suppress the significant edge effect that occurs in tightly coupled dipoles, coupled grounded posts are added to the surrounding dipoles, effectively attenuating edge reflections and significantly expanding the bandwidth to lower frequencies. A periodic patch superstrate is loaded above the dipoles to improve the impedance matching and radiation performance. A prototype was fabricated and measured, showing a bandwidth is 1.8–12.5 GHz (149.7%) with VSWR $<$ 2.2, fully covering the S, C, and X bands. The proposed antenna is printed on a thin substrate and its size is very small, only $33\times 33\times 18.2$ mm ($0.2\times 0.2\times 0.11{\lambda }_L$), where the ${\lambda }_L$ is the wavelength of the lowest operating frequency.