Miniaturized inverted ultra-wideband multiple-input multiple-output antenna with high isolation

For the ultra-wideband (UWB) transmission requirements in wireless communication systems and better miniaturization of mobile terminal antennas, a compact UWB multiple-input multiple-output (MIMO) antenna with higher isolation between units is proposed. The MIMO antenna consists of two semi-circular antenna units and a defective ground structure. By improving the structure of the ground plane, the antenna units are placed upside down by taking advantage of the inherent directional radiation characteristics of the antenna units, thereby achieving higher isolation. The proposed antenna size is 15 x 22 x 1.6 mm(3). The measurement results show that the proposed UWB MIMO antenna satisfies the port reflection coefficient S-11 < -10 dB in the 3.4-12.9 GHz band, and the isolation is all greater than 25 dB, which has high isolation. The allowable limit of the envelope correlation coefficient ensures good MIMO performance, which can meet the requirements of UWB wireless communication in practical engineering applications.