Compact Dual-Polarized/Duplex Filtering Antenna With High Isolation

This paper introduces novel dual-polarized/duplex filtering antennas with a novel filtering feeding network. The feeding network consists of an all-resonator structure, which shares a common dualmode resonator. This structure facilitates the isolation of two well-isolated channels through the exploitation of the even and odd modes of the dual-mode resonator. By applying balanced excitation to the odd mode and unbalanced excitation to the even mode, the two modes can be separated, creating a hybrid-like feeding structure. Despite the common resonator, the channels exhibit high isolation, and the overall size of the filtering circuit is much smaller than conventional cascaded-resonator designs. To demonstrate the effectiveness of the proposed feeding network, we have designed, fabricated, and measured a dual-polarized and a duplex filtering antenna. The simulated and measured results agree well, showing isolations greater than 34 dB and 38 dB for dual-polarized and duplex cases, respectively. Our proposed antennas are compared with state-of-the-art developments, demonstrating the advantages of compact size, flexible decoupling frequency ratio, and high isolation.