Mutual coupling reduction between elements of UWB MIMO antenna using small size uniplanar EBG exhibiting multiple stop bands

In this paper, mutual coupling reduction between elements of UWB MIMO antenna using small size uniplanar EBG is presented. Proposed UWB antenna geometry consists of two circular shaped monopole radiator swith a slot in ground plane for proper impedance matching. A UC-EBG (Uniplanar Electromagnetic Band Gap) cell of size 6.8 mm x 6.8 mm is inserted between the antenna elements in 4 x 1 array configuration to improve the isolation. Bandgap of the UCEBG is determined using dispersion diagram and suspended stripline method. The proposed antenna is fabricated on 1.6 mm thick, low cost FR4 substrate, possessing an overall size of 27.2 mm x 46 mm. The antenna has been fabricated and experimentally verified. The antenna shows simulated and measured -10 dB impedance bandwidths of 14.6 GHz (3-17.6 GHz) and14.8 GHz (3.6-17.9 GHz) respectively. UCEBG structure exhibits multiple stop bands and suppresses E-plane coupling over these bands. Isolation better than -18 dB is achieved over the complete impedance bandwidth. Radiation efficiency and peak gain of the antenna varies from 78% to 96.7% and 1.4 dB to 4 dB respectively. MIMO parameters, i.e. error correlation coefficient (ECC) better than0.018 and Total active reflection coefficient (TARC) better than - 26 dB is achieved over the impedance bandwidth.