Two different four-port reconfigurable diversity antennas have been realized with dimensions 60 mm × 60 mm for 5G devices by deployment of PIN diodes for frequency reconfigurability. The first MIMO antenna comprises a four-slotted rectangular patch as an antenna element, while the second MIMO antenna consists of a triangular slotted patch as an antenna element. By switching the diodes ON and OFF, the frequency with minimum return loss of the antenna can be altered. In the first design, the resonance frequency of antenna varies from 4.7 GHz to 4.9 GHz, while in the second design, the resonance frequency varies from 6.8 GHz to 7 GHz. The resonance frequencies get altered due to change in the patch geometry in the designs at different functional conditions of the PIN diodes. In the first design, four PIN diodes are incorporated in each patch, while in the second design, one PIN diode has been used in each microstrip patch. A reflective metasurface has been constructed for exhibiting resonance at the frequency matching with that of the antenna so that it can cause its gain enhancement by 2 dB when placed 10 mm below the antenna. The metasurface comprises a periodic pattern of a circular patch inscribed within a hexagonal ring. The radiated waves from the antenna are reflected from the metasurface to give a stable maximum gain of 4 dBi. The presumed metasurface-integrated antenna can be used in 5G communication systems. Numerical simulations have been conducted using finite integration technique.