Abstract: Objectives To address the reduced communication efficiency caused by the limited installation space of shipborne communication equipment and interference from other onboard devices, a compact frequency reconfigurable ultra-wideband (UWB) antenna incorporating four notched bands is proposed. Methods By incorporating two inverted U-shaped slots into the radiating patch, and a split-ring resonator together with a rectangular open-slot resonator is introduced near the feed line to generate four notched frequency bands. PIN diodes are inserted between the two inverted U-shaped slots and controlled by a biasing circuit, enabling frequency reconfiguration of the antenna under four operating modes by switching the diode states. Results Simulation and measurement results demonstrate that the proposed antenna has an overall compact size of 35.5 mm × 30 mm × 1.6 mm and operates across a broad frequency range of 2.43  GHz to 12.00  GHz. Under the four operating modes, independent notched bands corresponding to the WiMAX/C-band satellite downlink (3.42-4.09 GHz), WLAN band (4.72-5.44 GHz), C-band uplink (5.86-6.35 GHz), and ITU band (7.94-8.68 GHz) are achieved. The antenna exhibits a maximum gain of 3.87 dBi and exhibits excellent omnidirectional radiation characteristics. Conclusions The proposed antenna achieves four reconfigurable band-notched characteristics within a compact structure, effectively suppressing multiple narrowband interferences. It is well suited for UWB wireless systems operating in complex interference environments, such as ship formation communications and maritime unmanned aerial vehicle swarm links.