Abstract: The ultra wide band (UWB) antenna is a key component of wide band electromagnetic system. This paper researches the problems of electromagnetic simulation and performance experiment of a log periodic folded slot antenna (LPFSA). A LPFSA fed by coplanar waveguide is designed, according to the basic principles of the log periodic dipole antenna (LPDA). The VSWR characteristics of the antenna in the low frequency band are improved by loading phase slot in the center conductor of the folded slot unit. The measurement of the phase slot loaded LPFSA was done. The experiment results show that the VSWR is less than 3. 5 within the frequency range of 2 GHz to 18 GHz, which were in good agreement with the simulation results. The conformal LPFSA is designed using the phase slot loaded LPFSA, and the corresponding simulation results are provided. The research work can provide a technical reference for the practical application of LPFSA.