This work presents a compact dual-band two-port multiple input multiple output (MIMO) antenna with high performance that is specifically used for 5G applications. The proposed design comprises closely spaced, mirror-symmetrical X-shaped structures positioned at an edge spacing of 0.02 λ0 between antenna elements. Subsequently, a metasurface is located at a distance of 0.27 λ0 above the radiator to improve the performance of the MIMO antenna. The proposed antenna resonates at 3.27 GHz within a frequency range of (3.03–3.44) GHz in the primary band, achieving a peak realized gain of 7.57 dBi. In the secondary band, the resonance occurs at 4.78 GHz with a range of (4.01–5.87) GHz below −10 dB reflection coefficient and produces a peak realized gain of 5.60 dBi. After positioning the metasurface on top of the reference antenna, the peak realized gain improves by 116.28 % in the primary band and 69.69 % in the secondary band respectively. Whereas the isolation is increased to −30.01 dB from –22.26 dB in the primary band, similarly for the secondary band the isolation is amended to −21.00 dB from −18.20 dB. Moreover, circular polarization is realized at working frequencies after placing the metasurface on the reference antenna. Simulation and measurement results prove that the S-parameters exceed more than −20 dB in both frequency bands. Additionally, MIMO performance metrics, including envelope correlation coefficient (ECC), channel capacity loss (CCL), total active reflection coefficient (TARC), mean effective gain (MEG), and diversity gain (DG) are simulated and measured. The designed antenna proves suitable for the new radio (NR) 5G of n48 (3.55–3.70 GHz) in the primary band and the n79 (4.4–5.0 GHz) in the secondary band respectively.
