Dual-Layer Dual-Patch Ebg Structure for Isolation Enhancement and Correlation Reduction in Mimo Antenna Arrays

Abstract

This paper proposes a novel electromagnetic band gap (EBG) structure based on a duallayer 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 × 7 dual-layer DLDP-EBG unit cell is inserted between the array elements to reduce the mutual coupling and deflect 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 deflecting the radiation beams of the individual antenna elements in opposite directions. The MIMO array gain and radiation efficiency 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-profile MIMO slot antenna array is the first in literature to exhibit such wideband isolation improvement, gain enhancement, and correlation reduction behavior simultaneously.

Ridge gap waveguide antenna array with improved mutual isolation for millimeter wave applications

“…The PMC unit cell (see Figure 1(A)) specifies the needed stopband (i.e., bandgap) that takes place over the frequency range where no possible propagating modes are available 22 . This frequency band is basically specified by the dimensions of the mushroom‐like unit cell and the air gap to the upper plate.…”

“…Frequency selective surfaces (FSS) are widely used to filter out the coupling currents using defected ground surface (DGS) 18,19 or electromagnetic band gap (EBG) structures. Periodic EBG surfaces with and without plated vias are efficient in reducing mutual coupling between antennas at the cost of electric loss and fabrication challenges 20‐22 . The authors in Ref.…”

“…20 presented one of the early designs that employed EBG two‐dimensional structure between two patch antennas, finite‐difference time‐domain (FDTD) method was used to analyze the whole radiating system and an 8 dB isolation improvement has been measured. Recently, Sokunbi et al 22 proposed the use of dual‐layer dual‐patch EBG structure to improve the isolation and reduce the envelop correlation coefficient (ECC) between the elements of MIMO slot antennas array, they achieved an isolation enhancement of up to 56 dB over the frequency band of 4.2–6.5 GHz.…”

A Novel Compact Highly Isolated UWB MIMO Antenna with WLAN Notch

“…Various techniques have been used for isolation enhancement such as Defected Ground Structure (DGS) [2,3], Electromagnetic band gap (EBG) [4][5][6][7], Parasitic Element [8][9][10][11], complementary split ring resonators [12][13][14], metallic stubs and shorting pins [15][16][17][18], and neutralization line [19,20]. For instance, in [2], S-Shape periodic defected ground structure (PDGS) is used for coupling reduction.…”

“…Moreover, isolation can also be improved by making multiple rectangular shape DGS in between patch antennas [3]. In [4], EBG is used in the ground plane for improving isolation between patch antennas. A novel EBG is etched in the ground plane to stop EM waves propagation in a particular band.…”