Frequency Reconfigurable Two-element MIMO Antenna for 3G/4G/5G Cellular Communications

A frequency reconfigurable two-element multiple input multiple output (MIMO) antenna with inverted-E shaped unit radiator is designed and presented in this communication. The proposed MIMO Antenna can be electrically reconfigured in two distinct operating modes. In the first mode, it operates at all the 3G (1800 MHz, 2100 MHz), 4G (2300 MHz) and mid-band 5G (3500 MHz) bands of cellular communication whereas in second mode, it operates at 3500 MHz mid-band 5G only. The unit radiator of the MIMO is an inverted-E shaped monopole resonator which achieves its resonant modes by varying the feed position. The isolation of the MIMO has been enhanced from 4 dB to 22 dB using a square split ring resonator (SRR) at the ground plane. The MIMO offers above 300 MHz bandwidth and more than 12 dB gain throughout the operating bands. The performance of the MIMO in diversity environment has been examined using all the standard MIMO parameters like envelope correlation co-efficient ($\text{ECC} < 0.06$), diversity gain ($\text{DG} > 0.98$), total active reflection co-efficient $(\text{TARC} < -20\ \text{dB})$, mean effective gain ($\text{MG} < 0.5\text{dB}$) and channel capacity loss $(\text{CCL} < 0.1 \text{bits}/\text{sec}/\text{Hz})$.