Millimeter-Wave Switchable Quadri-Polarization Array Antenna Based on Folded C-Type SIW

Array antennas with multipolarization function have important research value to improve the stable transmission of communication systems by supporting antenna diversity technology. In this letter, a millimeter-wave (mm-wave) quadri-polarization array antenna based on folded C-type substrate integrated waveguide is proposed. The operating principle is that the proposed differential feeding network can flexibly provide the required amplitude and phase difference, so that four mutually perpendicular single-branch slot array antennas can achieve multiple polarization characteristics. In addition, by removing the metal floor around the array antenna, the distortion of the antenna's main beam is suppressed. Simulation and experimental results show that the proposed quadri-polarization array antenna can provide orthogonal dual-linear polarization and dual-circular polarization radiation patterns. At the same time, it has the advantages of low profile and easy integration.