In this paper, a dual-band modified multiple-input-multiple-output (MIMO) antenna with high isolation is presented and discussed. The proposed compact structure (35×25 mm2) consists of two monopole elements and defected ground planes to obtain high impedance bandwidth. Two elliptical-shaped patches are placed orthogonal to each other to obtain high isolation, and a neutralization slit is integrated into the ground plane of each element to further improve the isolation between the elements. The measurement results of the proposed structure show satisfactory agreement with the simulation results. The measured bandwidths are 47.05% (2.6-4.2 GHz) and 64.72% (5.11-10 GHz) at S11 ≤ -10 dB which covers bandwidth requirements of WiMAX (3.4-3.6 GHz, 5.25-5.85 GHz), sub 6 GHz 5G band (3.4-3.8 GHz), WLAN (5.15-5.35 GHz, 5.725-5.825 GHz), and X band satellite communication systems (7.25–8.39 GHz). The designed antenna offers a peak gain of about 9.0 dBi and radiation efficiency of about 92%. The measured minimum isolation is greater than 27.3 dB across the dual band with a maximum value of 73.4 dB. The envelope correlation coefficient (ECC) is below 0.0035, channel capacity loss less than 0.37 bits/s/Hz, and peak diversity gain about 10 dBi.