Design of dual polarized patch antennas fed by hybrid feeds

We propose new designs of broadband dual-polarized patch antennas fed by hybrid feeds of an aperture-coupled feed and a gap-coupled feed or an aperture-coupled feed and a capacitively-coupled feed. For these hybrid feed designs, since the gap-coupled feed or the capacitively-coupled feed has no backward radiation, their possible port coupling with the aperture-coupled feed in the region between the ground plane and the reflecting plate will be eliminated, which facilitates the design problem when a reflecting plate is required for practical applications. Also, for the proposed antennas with a thick air substrate studied in this article, the 10-dB return-loss impedance bandwidths for the two polarizations can both be greater than 10% and high isolation (>-30 dB) between the two feeding ports over the entire impedance bandwidth can be obtained. Good cross-polarization levels for the radiation patterns of the two polarizations are also observed.