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 2[Formula: see text]GHz to more than 12[Formula: see text]GHz with high isolation characteristics of more than 20[Formula: see text]dB and insertion losses around 3.3[Formula: see text]dB. The designed WPD is then applied to feed two UWB monopole antenna arrays which offer a notched band centered at 5.5[Formula: see text]GHz 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 (3.5–11.8[Formula: see text]GHz for [Formula: see text] array and 3.6–12[Formula: see text]GHz for [Formula: see text] array) that includes the UWB spectrum. Attractive agreement between simulation and measurement results is obtained. Furthermore, the bending test is carried out on the [Formula: see text] array showing the good performance of the proposed system when installed on curved surfaces for different bent angles.