Additively Manufactured Dual Circularly Polarized Antennas With Bidirectional Same-Sense Radiation and Wide Bandwidth Characteristics

This communication presents two additively manufactured bidirectional circularly polarized (CP) antennas. Each antenna radiates the same-sense CP waves in opposite directions and has the capability of altering the CP state to either right-hand CP (RHCP) or left-hand CP (LHCP) by switching the feeding ports. They adopt the same scheme of combining a linearly polarized (LP) bidirectional source and two polarizers of the same type. Different polarizers, a single-slab dielectric polarizer (Ant 1) and a linearly tapered slot polarizer (Ant 2), are proposed and applied for them, respectively. The LP source adopts a circular waveguide-based structure. By altering the orthogonal degenerate modes in the waveguide, the CP states can be switched correspondingly. To validate the design ideas, prototypes of the two antennas are fabricated and tested. Experimental results show that the axial ratio bandwidth (ARBW) of Ant 1 and Ant 2 is 30.3% (4.9–6.66 GHz) and 17.9% (5.26–6.3 GHz), respectively. Within the ARBW, their gain is 8.4± 0.8 and 7.2± 1 dBic, respectively. These results demonstrate that both antennas exhibit the advantages of wide band, high gain, and ease of fabrication over the conventional designs.