Flexible ultra-wideband (UWB) antenna arrays with band notching characteristics are proposed in this work. A new wideband and high-isolation Wilkinson power divider (WPD) is designed to construct the feed systems of the UWB antenna arrays. The proposed WPD is achieved by introducing a significant modification to the conventional WPD and the new one is composed of four isolation stages. Multiple stages helped to achieve wideband from 2GHz to more than 12GHz with high isolation characteristics of more than 20dB and insertion losses around 3.3dB. The designed WPD is then applied to feed two UWB monopole antenna arrays which offer a notched band centered at 5.5GHz to reject interference from wireless local area network (WLAN) system and can be integrated with curved surfaces. To verify the performance of the proposed structure, two array configurations are practically fabricated and measured. The results show that both the arrays have UWB operational bandwidth (3.5-11.8GHz for 1×2 array and 3.6-12GHz for 1×4 array) that includes the UWB spectrum. Attractive agreement between simulation and measurement results is obtained. Furthermore, the bending test is carried out on the 1×4 array showing the good performance of the proposed system when installed on curved surfaces for different bent angles. © 2021 World Scientific Publishing Company.