Objective To address the limited installation space and strong mutual coupling encountered in shipborne communication systems, this study proposes a compact, low-coupling, ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna. The goal is to enhance system reliability and communication efficiency under complex electromagnetic environments typically found in naval platforms.

Method The front-side radiating patch of the antenna adopts a combination of rectangular and semicircular shapes, along with chamfered corners, to optimize impedance matching and achieve wideband coverage. The innovation on the backside lies in the introduction of a composite decoupling structure that integrates porous parasitic patches and defected ground structures (DGS), endowing the antenna with low coupling characteristics. To further enhance anti-interference performance, an inverted U-shaped slot is etched into the radiating patch to generate a notch band targeting the satellite C-band uplink frequency range (5.925～6.425GHz). The antenna is fabricated on a 1.6 mm thick FR4 substrate, which provides a good balance between mechanical strength and cost efficiency, with overall dimensions of 30 mm×24 mm×1.6 mm.

Results Simulated and measured results demonstrate that the antenna supports stable operation across a wide frequency range of 2.95～20 GHz. The reflection coefficient remains consistently below −10 dB, and the isolation consistently exceeds 19 dB, with a peak isolation of up to 40 dB observed in higher frequency bands. The envelope correlation coefficient （ECC） is less than 0.005, and the diversity gain DG remains above 9.9 throughout the entire operating range. The antenna also achieves stable omnidirectional radiation with gain levels maintained between 0 and 5 dBi. The introduced notch structure effectively eliminates interference within the designated C-band uplink frequency range.

Conclusion The proposed UWB-MIMO antenna offers advantages such as compact structure, wide bandwidth, high isolation, and strong anti-interference capability. It demonstrates excellent performance and engineering feasibility, making it well-suited for modern shipborne wireless communication systems and showing great potential for practical engineering applications.