This work proposes a novel 2×2 MIMO antenna module with a dense 16-port configuration, engineered for seamless integrationinto the rear cover of mobile devices while meeting compliance requirements for next-generation 6G applications. Designed ona low-profile footprint of 55 mm × 55 mm × 1.8 mm and optimized through full-wave simulations in Ansys HFSS, the 16-portantenna module operates within the new international mobile telecommunication spectrum (7–24 GHz). Resonance is observedin the 10.7–13.25 GHz sub-band, an operational range that remains largely unexplored in recent compact MIMO antennadesigns. A novel approach of introducing an air gap between the substrate and the ground plane is employed to enhance theantenna performance. The proposed antenna is fabricated and experimentally characterized to validate its performance, andthe measured results show good agreement with the simulation results. Surface power density measurements confirm thatthe antenna operates within the safety limits specified by the ICNIRP guidelines, supporting its suitability for mobile deviceintegration. With the average gain across the ports greater than 6 dB, the design achieves a balance between compactnessand radiation performance.