A ridged TEM horn wideband antenna is designed to operate in the VHF band. Inspired by the fishtail structure and the classic ridged structure, the antenna's operating bandwidth at low frequencies is extended through a unique curved structure design. Compared with the conventional TEM horn antenna, the antenna designed in this paper achieve stronger directivity and widened frequency by using a unique shape structure and dielectric loading technology. Furthermore, we optimize the main structural parameters of the antenna. It can be seen from the simulation results that the antenna satisfies S11 less than -10dB in the ultra-short wave VHF operating frequency range 65 ~ 308MHz, and the antenna's radiation pattern and gain are wonderful. The result indicates that the antenna has potential for application in ultra-short wave systems.