Abstract: Vivaldi antenna, a kind of tapered slot antenna, is widely used in the design of planar ultra wideband antennas. Vivaldi antennas can broaden the bandwidth infinitely in theory, but the improvement of the gain is not prominent because of the processing technology and the dimension. This paper loads the antipodal structural dielectric on the front of the radiation structure. The results indicate that the relative bandwidth broadens by 79.1% and the gain increases 3 dBi at 5.5 GHz and 12 GHz. The technology of slotting correction makes the radiation phrase distribution more symmetrical, thus enhancs the efficiency of the amplitude distribution. The results indicate that the gain increases 2 dBi through loading the technology. Both technologies in the design own the merits of high gain, simple design and miniaturization, which provides a new idea for end-fire antenna gain and directivity improvement.