This paper compares two dual-polarization (DP) MIMO systems with compact size, full isolation, and channel capacity for modern applications. Demonstrates two different designs of compact ultra-wideband (UWB) antennas. It presents two different designs of compact ultra-wide-band (UWB) antenna. These antennas are manufactured and designed to fit and compare to a four-element MIMO system. The first design is a compact UWB cup-antenna with a notch in the partial ground plane. The second design is a coplanar waveguide (CPW) UWB antenna. In this paper, the isolated coefficient for two dual-polarization (DP) and the channel capacity of the MIMO system is calculated to achieve the optimum antenna system for modern communications that are very low, approximately -20 dB. Further, the BW and channel capacity of these designs are better than the other previous works. The simulation results are taken using CST STUDIO SUITETM 2018. Furthermore, there is a great agreement between simulations and fabricated results.