High Isolated Four Element MIMO Antenna for ISM/LTE/5G (Sub-6GHz) Applications

A compact quad-port Multiple-Input-Multiple-Output (MIMO) antenna with an electrical dimension of
$0.28\lambda _{0}\times 0.28\lambda _{0}$
and impedance bandwidth of 5.03GHz (2.42-7.45GHz) is proposed. By combining a tapered feed line and stubs in the ground plane, which serve as open circuit stubs and whose dimensions are properly tuned to compensate for the antenna’s input impedance, as the inductance and capacitance values are dependent on it, the bandwidth and isolation are improved. The MIMO antenna has a 15dB average isolation and a group delay < 1nsec. In terms of the envelop correlation coefficient (ECC), diversity gain (DG), mean effective gain (MEG), and total active reflection coefficient (TARC), the proposed antenna’s diversity performance characteristics are investigated, and the obtained values are 0.004, 9.99dB, ±3dB, -10dB respectively. Further the channel capacity of the MIMO antenna is also calculated. The maximum channel capacity of the four elements is 21.34bits/sec./Hz. Equivalent circuit of the proposed MIMO is discussed in this article and S-parameter has been compared with simulated results and found good agreement between simulated and circuit results. A prototype was created to compare the calculated parameters with the measured ones to validate the suggested design. In addition, the scattering matrix, which includes the reflection coefficient (S11) and transmission coefficient (S21) between two elements, and other antenna parameters are all advantageous for applications in the Bluetooth (2.400-2.483GHz), ISM band (2.40-2.483GHz, 5.725-5.850GHz), WLAN/Wi-Fi, and 5G (sub-6GHz) bands.