This paper presents the design of a miniaturized polyimide-based antenna for Ultra-Wideband (UWB) communication. Miniaturization is achieved through the utilization of adhesive material with a high dielectric constant (high-Dk). The goal of this work is to investigate the impact of such material on the antenna performance and to optimize its design for UWB operation. The manufacturing of the antenna using the proposed structure was developed and the prototype of antenna for UWB high-band (6 - 9 GHz) is measured and analyzed. By leveraging the high Dk of the adhesive material, the simulation and measurement results showed that the proposed antenna with high Dk adhesive film can achieve the compact dimension with good performance in gain, and time domain characteristics. The results of this study show a potential of exhibiting a reduction in the size of the antenna and will contribute to the advancement of miniaturized UWB antenna technology.