Broadband dual-polarized antenna for active array applications

A broadband dual-polarized microstrip antenna is presented. It uses the aperture-coupled feed for one polarization, while the microstrip line feed with slotted ground plane is used for the other polarization. The antenna can make good use of the space on both sides of the ground plane, as the feed circuits for two orthogonal polarizations are placed on each side of the ground plane, respectively. By using only one patch, the prototype antenna yields a bandwidth over 17% at both ports, and an isolation below -32 dB. Good broadside radiation patterns are observed, and the cross-polar levels are below -18 dB at both E- and H-planes.