Dual-port planar MIMO antenna with ultra-high isolation and orthogonal radiation patterns

A dual-port planar MIMO antenna designed for 2.4 GHz WLAN applications is presented. It consist of two X-shaped arms etched on a square-shaped substrate, which forms a self-decoupled structure that can generate two orthogonal modes with ultra-high isolation. In measurement, the -10 dB bandwidth covers from 2.39 to 2.51 GHz, and better than 43 dB isolation is achieved between the two ports. Meanwhile, the patterns are orthogonal, and the envelope correlation coefficient is only 0.0052. The antenna it is fabricated on FR-4 substrate, and the size is only 33 × 33 × 3.2 mm, which is very much suited to space-limited MIMO applications that require ultra-high isolation, good pattern diversity and low fabrication cost.