Abstract: For the positioning needs of mobile devices, electric vehicles, and smart transportation systems, ultra-wideband positioning systems require integration into increasingly compact device spaces. However, the traditional Vivaldi antenna's large size makes them unsuitable to meet these demands. In this paper, we propose a new compact Vivaldi antenna is proposed. By optimizing the exponential opening function of the Vivaldi antenna is optimized as the basis, and rhombic and rectangular slots are introduced on the surface of the antenna patch to prolong the surface current path, so as to broaden the bandwidth and improve the return loss performance of the antenna. Simulation results demonstrate that the proposed slots enhance the antenna’s low-frequency response, achieving an S₁₁<−10 dB over a bandwidth of 4.7 GHz~14.75 GHz. The designed antenna has a size of 26 mm×25 mm×0.8 mm, and the fraction bandwidth reaches 103.13% with the maximum gain of 7.5 dBi. This compact design exhibits strong performance, compact size, and wide bandwidth in the operational bands, making it suitable for ultra-wideband positioning, wireless communications, and integration into portable devices.