This paper proposes a novel electromagnetic band gap (EBG) structure based on a dual-layer dual-patch unit (DLDP-EBG) cell to improve isolation and decrease envelope correlation between MIMO slot antenna array elements. A wideband MIMO slot antenna array operating in the frequency range of 4.2-6.5 GHz (43%) is deployed. The antenna array is based on slotted rectangular microstrip radiating elements printed on the top surface of two stacked FR4 substrates to widen the array impedance bandwidth. A 2 x 7 dual-layer DLDP-EBG unit cell is inserted between the array elements to reduce the mutual coupling and detect the individual beams of each antenna in opposite directions. An isolation improvement of up to 56 dB is maintained throughout the working bandwidth of the antenna, when the EBG is inserted. Also, the DLDP-EBG unit cells reduce the envelope correlation coefficient by 5-30 dB across the whole operating bandwidth by detecting the radiation beams of the individual antenna elements in opposite directions. The MIMO array gain and radiation eciency have been improved after using the EBG structure due to the reduction in mutual coupling and surface wave mitigation between the array elements. The proposed low-prole MIMO slot antenna array is the first in literature to exhibit such wideband isolation improvement, gain enhancement, and correlation reduction behavior simultaneously.
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