High Isolation Compact UWB MIMO Antennas

In this work, two elements and four elements compact UWB MIMO antennas are designed and fabricated. A printed circular disc with five circular slots is selected in this work due to its UWB performance and compact size for the MIMO antenna system. CST software is used in the simulation process. Measured S parameters show that the MIMO antennas work well from 3 GHz up to 20 GHz (maximum working frequency of the measurement instruments). The two elements MIMO antenna has a size of 70 × 40 mm2 meanwhile the four elements MIMO antenna has a size of 70 × 70 mm2. Measurement results show that the isolation among the antenna elements is higher than 20 dB. The envelope correlation coefficient, diversity gain, channel capacity loss, mean effective gain and total active reflection coefficient are studied in this paper. Simulations results show that the MIMO antennas have a satisfactory performance up to 50 GHz.