Wideband Directional Base-Station Antenna with Dual-linear and Circular-Polarization Capabilities

A crossed-dipole antenna providing polarization diversity is presented. The antenna which employs a planar reflector yields high directivity and good isolation between ports over a wide impedance bandwidth, suitable for polarization-agile wireless base-station use. The dipole wing shape is optimised, which yields the wide bandwidth. Matching is achieved using a quarter-wave balanced-to-unbalanced section which also improves the port-to-port isolation. Radiation characteristics for linear and circular polarizations are presented