In this work metasurface based frequency reconfigurable two-port multiple input multiple output (MIMO) antenna is presented. Initially, the proposed antenna is configured as a single-port radiating patch with pin-diode operating in the frequency reconfigurable mode. Later the designed antenna is converted to a two-port MIMO antenna that realizes an S11 below -10 dB intended for two resonant bands operating at 2.95 GHz (2.71-3.33 GHz) and 4.91 GHz (4.48-5.24 GHz) with pin-diode off-mode and 3.69 GHz (2.60-4.79 GHz) in on-mode with maximum peak realized gain of 6.29 dB and 4.13 dB at diode off-mode and 9.84 dB in diode on-mode. The two feeding ports of the proposed antenna are positioned adjacent to each other to permit the antenna in self-isolation mode later metasurface-reflector is placed below 10mm of radiator used as a de-coupling circuit and maintaining the minimum isolation of (S21) below -18.5 dB and maximum isolation of -23.07 dB in off-mode and -20.48 dB in diode on-mode. Moreover, the isolation and peak realized gain has improved after adding a reflector to the proposed antenna. The distance between antenna elements is 0.04 λo. The designed antenna is applicable for 5G new radio (NR) bands of n7, n48, n77, and n78 in on-mode, and n79 in diode off-mode respectively.
