To address the challenges of limited installation space and strong mutual coupling in shipborne communication systems, this study proposes a miniaturized ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna with enhanced decoupling performance. The goal is to improve system reliability and communication efficiency under complex electromagnetic conditions as typically found on naval platforms.

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. On the backside, a novel composite decoupling structure is introduced, integrating porous parasitic patches and defected ground structures (DGS) to achieve low mutual coupling. By etching an inverted U-shaped slot into the radiating patch, the antenna generates a notch band at 5.71–6.56 GHz, which fully covers the satellite C-band uplink frequency range (5.925–6.425 GHz), thereby effectively suppressing interference signals in this band. The antenna is fabricated on an FR4 substrate with a thickness of 1.6 mm, offering a balance between mechanical strength and cost efficiency. The overall dimensions are 30 mm×24 mm×1.6 mm.

Simulated and measured results demonstrate that the antenna achieves stable performance over a wide frequency range from 2.95 to 20 GHz. The reflection coefficient is maintained below −10 dB, while the isolation exceeds 19 dB throughout, reaching up to 40 dB at higher frequencies. The envelope correlation coefficient (ECC) is less than 0.005, and the diversity gain (DG) remains above 9.9 across the entire operating band. The antenna also achieves stable and omnidirectional radiation, with gain levels maintained between 0 and 5 dBi. The introduced notch structure effectively suppresses interference within the designated C-band uplink frequency range.

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