Dual-band dual-circularly polarized patch antenna with integrated design of coupling structure and stepped-impedance resonators

Abstract In this paper, a dual-band dual-circularly polarized (CP) patch antenna with integrated coupling structure and stepped impedance resonators (SIRs) is proposed. The tapped-line coupling generates $0^{\circ}/180^{\circ}$ phase in two frequency bands, while the parallel coupled-line coupling exhibits an inherent $90^{\circ}$ phase delay in two frequency bands. The two-way coupling structure generates the $\pm90^\circ$ phase shift enabling dual-CP, eliminate the need for additional phase shifters. Then, the SIRs excite the two orthogonal modes of the radiation patch while concurrently matching the impedance between the antenna and the input port, eliminating the need for an additional matching network. Finally, the radiation patch and SIRs are integrated into a complete structure, and a T- junction is used to connect the two branches. Compared to traditional design, the proposed antenna greatly reduces the complexity and difficulty. The development stages are discussed in detail. The proposed design is demonstrated through prototype fabrication and characterization.