Dual-polarised slot-coupled patch antenna excited by a square ring slot

A novel slot-coupling feeding technique for dual-polarised patch antennas is presented. A square patch is fed through a square ring slot excited by two non-overlapping feed lines printed on the same side of a single-layer substrate. With respect to other slot-coupling feeding techniques for dual-polarised patch antennas, the configuration here proposed exhibits a simple structure and a valuable symmetry property with respect to the two feeding ports, while preserving a satisfactory isolation. To show the working principle and the radiation properties of the proposed slot-coupled patch, a sample antenna operating in the 3.3-3.8-GHz WiMAX^™ frequency band has been designed, prototyped and characterised.