Single radiator four-port MIMO antenna for WLAN and WIMAX applications with high isolation

A single radiator four-port multiple-input-multiple-output (MIMO) antenna for WLAN and WIMAX applications is presented. The proposed antenna is composed of a single radiating element and a square ring ground. To reduce mutual coupling among antenna ports, the four feeding ports are placed perpendicular to each other in order to mismatch their polarization. By introducing radiation stubs and ground stubs, impedance matching and isolation is improved. The measured results show a −10 dB reflection coefficient bandwidth is from 4.5 to 7.0 GHz (covering the 5.2 GHz/5.8 GHz WLAN and the 5.5 GHz WIMAX bands), and the isolation between various ports below −25 dB.