Closely‐coupled wideband MIMO antenna with isolation improvement using decoupling circuit and hexagonal split‐ring resonators

Abstract

In this paper, a design of a closely‐coupled wideband multiple‐input–multiple‐output (MIMO) antenna using a new simple wideband decoupling circuit (DCkt) based on a 2nd order filter for isolation improvement is presented to decouple the wideband MIMO antenna array. The wideband closely‐coupled MIMO antenna and the DCkt are designed using the structure's admittance parameter. To achieve good isolation in wide‐bandwidth six hexagonal split‐ring resonators are utilized. The presented closely‐coupled wideband MIMO antenna is resonating at 5.08–6.30 GHz (WLAN) bands, with measured isolation (>25 dB) in the 5.12–5.98 GHz frequency range. The envelope correlation coefficient is less than 0.1, and channel capacity loss (Closs) is less than 0.05, along with good radiation characteristics. It exhibits an exceptional expansion that makes the proposed solution the right candidate for advanced technological applications such as 5G and IoT.

Self-isolated MIMO antenna using mixed coupling by close coupling technique

“…Numerous approaches in the previous works of MIMO antennas to increase the isolation have neutralization line, defected ground structure (DGS), metamaterial, and Electromagnetic Band Gap (EBG) [3][4][5][6][7][8][9][10][11][12][13][14] . The narrow open-ended slots and space diversity 3 , DGS in the ground plane 4,7 , the vertical ground strip with EBG structure in the top plane orthogonally arranged patch antenna 5 , the shorting stub 6 , the complementary-split-ring-array (CSRA) 8 , loading split-ring-resonators (SRR) [9][10][11] , complementary slot coupled SRR 12 , the planar EBG structure 13 , 2nd order de-coupling circuit 14 are applied in the MIMO antenna, which in turn leads to isolation improvement. Phase-gradient metasurfaces (PGMs) are used to deflect an antenna beam in a preferred direction 15 .…”

Cavity‐backed substrate integrated waveguide MIMO element with enhanced isolation for 5G communication

“…18 Hexagonal-SRR and decoupling second-order filter circuit are placed in proximity to the octagonal-shaped wideband MIMO antenna for enhancement of isolation at 5G-WLAN application. 19 The meta-surfaces-based multiple decoupling techniques are reported in literature such as decoupling structures between adjacent elements to minimize EM coupling, 20 metasurface-SRR as decoupling unit printed on same surface, 21 superstrate, 22 or downstrate, 23 and double-negative (DNG) metasurface-based antenna 24 is reported for size reduction, wide bandwidth, and isolation enhancement of 5G-MIMO wireless application. The dielectric resonator antenna is positioned in closed loop, 25 opposite each other, 26 to obtain enhanced isolation since the magnetic fields excited inside the radiator are out of phase (180 ).…”

“…The orthogonal placement of staircase four element planar antenna loaded with complementary‐SRR is placed above and bottom layer to enhance the performance for 5G mm‐wave application 18 . Hexagonal‐SRR and decoupling second‐order filter circuit are placed in proximity to the octagonal‐shaped wideband MIMO antenna for enhancement of isolation at 5G‐WLAN application 19 . The meta‐surfaces‐based multiple decoupling techniques are reported in literature such as decoupling structures between adjacent elements to minimize EM coupling, 20 metasurface‐SRR as decoupling unit printed on same surface, 21 superstrate, 22 or downstrate, 23 and double‐negative (DNG) metasurface‐based antenna 24 is reported for size reduction, wide bandwidth, and isolation enhancement of 5G‐MIMO wireless application.…”