In this paper, a dual-port ultra-wideband (UWB) MIMO antenna is proposed, featuring a highly compact structure with dimensions of only 25 × 36 × 1.6 mm 3 . The designed antenna comprises two racket-shaped monopole antennas and a defective floor. Cross slots on the original T-shaped floor impede coupling current flow, significantly enhancing antenna isolation to achieve over 20 dB isolation across most frequency bands. The antenna operates at frequencies from 2.74 ∼ 14.8 GHz, meeting the stringent design criteria for UWB antennas. Furthermore, the diversity performance of the antenna is rigorously analyzed by simulating the envelope correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), and channel capacity losses (CCL). The designed antenna demonstrates excellent performance through comprehensive simulation and testing, showcasing its potential for applications in UWB MIMO systems.