Multiadapted Conformal Metasurface for Wideband Omnidirectional Circularly Polarized Antenna

This letter provides an omnidirectional linear-to-circular polarization converter (OLCPC) with adaptability for wideband high-gain omnidirectional circularly polarized (OCP) antenna design. The OLCPC is a cylindrical structure composed of periodically arranged conformal metasurface units. The unit could convert vertically linearly polarized electromagnetic waves within 40
$^\circ$
of the incidence angle to circular polarization ranging from 4.47 to 6.3 GHz (relative bandwidth 34.0%). To verify the polarization modulation performance and adaptability of the proposal, two different types of omnidirectional linearly polarized (OLP) antennas (biconical antenna and sleeve antenna) are used as radiation sources. Finally, prototypes of the OLCPC and two OLP antennas have been fabricated and measured, the measured results show that the OLCPC can increase the gain of the radiating source by 2 dBi and the OCP antenna system operating bandwidth can reach 33.7% (4.04–5.68 GHz). This study provides a flexible way to design an OCP antenna applied to the wideband high-gain communication system.