A very compact and closely spaced circular shaped UWB MIMO antenna with improved isolation

A very compact and closely spaced circular-shaped UWB - MIMO antenna with slotted T-shaped stubs and protruded strips for high isolation is discussed in the present paper. The fractional bandwidth of the proposed model reaches 134.68% from 2.82 GHz to 14.45 GHz with S11 < - 10 dB, which covers the unlicensed band 3.1-10.6 GHz approved by FCC in 2002 and X-band applications. The proposed model is fabricated on an FR-4 substrate having dimensions of 0.150 lambda(0) x 0.244 lambda(0) (16 x 26 mm(2)) and tested. The antenna elements in the proposed modal are separated by a small distance of 0.018 ko (2 mm). Due to T-shaped stubs and rectangular-shaped protruded strips, the isolation is improved to higher than 22 dB in most of the band. The proposed antenna achieves a maximum peak gain of 6.86 dB at 10.7 GHz. Radiation efficiency is above 91.70% for the entire band. The diversity performance metrics such as Envelope Correlation Coefficient (ECC), Diversity Gain (DG), and Total Active Reflection Coefficient (TARC) are studied and the values are lower than 0.08, greater than 9.984 dB and below -10 dB respectively. The measured and simulated values are found to be in good agreement. (C) 2019 Elsevier GmbH. All rights reserved.