Coupling reduction using a novel circular ripple-shaped decoupling mechanism in a four-element UWB MIMO antenna design

A 4*4 multiple-input multiple-output (MIMO) antenna with compact size and good isolation is presented for UWB applications. The concept of polarization diversity is here discussed and employed to satisfy contemporary wireless communication systems requirements. In the proposed antenna, the utilization of a novel circular ripple-shaped decoupling structure and a matching structure are presented to minimize mutual coupling of the inter-elements and enhance adaptation. Experimental results show a bandwidth range from 2.96 to 11.4 GHz with a good reflection coefficient which is S11 < −12 dB, high isolation S21 and S31 < −20 dB, good Envelope Correlation Coefficients ECC21 and ECC31 < 0.03, Diversity Gain DG21 and DG31 equal to 8.75, and a Total Active Reflection Coefficient (TARC) less than −12 dB. The antenna also exhibits a maximum gain of about 4 dBi with a maximum efficiency of 70% which proves that this antenna is a potential candidate for UWB applications.