Abstract: A miniaturized bidirectional beam antenna is designed for the ultra-wide band (UWB) precise positioning of personnel in coal mines. By arranging two U-shaped monopole antennas with λ/4 spacing and introducing a U-shaped slit structure on the metal ground, the bidirectional beam radiation characteristics is realized while ensuring a compact overall structure. The overall size of the antenna is 0.3×0.3×0.01λ3. The simulation and measurement results show that the -10dB bandwidth of the antenna is 1GHz (3.6~4.6GHz), which can effectively cover the working band of the current UWB precise positioning system in coal mines(3.7~4.2GHz). The designed antenna has a good amplitude-frequency response with a peak gain of 2.2~2.5dBi during the frequency band from 3.6~4.2GHz. The proposed antenna is suitable for various UWB precise positioning terminal devices used in mining.