An additively manufactured dual circularly polarized open-ended waveguide antenna using outer ridges with wideband characteristic

This paper presents a novel additively manufactured wideband dual circularly polarized (CP) open-ended waveguide (OEW) antenna, which adopts a pair of wedge-shaped outer ridges acting as a circular polarizer. Study found that compared to the con- ventional designs that employ internal polarization converting structures, such outer ridges are capable of achieving wider axial ratio bandwidth (ARBW) and better reflection coefficients. On each ridge, two rectangular slots are designed to suppress the higher order mode caused by the increased waveguide size, and further expanding the ARBW. The proposed antenna is fed by two differential ports. By switching the feeding ports, the CP states can be altered to either right-handed CP (RHCP) or left-handed CP (LHCP). In terms of configuration, the proposed antenna has a simple one-piece structure and is fabricated by using dielec- tric 3-D printing technology. To form the waveguide walls, its partial surfaces are coated by copper films through electroplat- ing. The proposed antenna features easy fabrication and light weight. Experimental results show that the proposed antenna has an impedance bandwidth of larger than 47.6% (8–13 GHz) with reflection coefficients lower than −15 dB, while the 3-dB ARBW is 37.7% from 8.4 to 12.3 GHz.