Abstract: The relationship between fidelity of pulse signals and phase-frequency and gain-frequency characteristics of ultra-wideband antennas is studied, and a technique to compensate for the transmission loss in free space via the design of antenna gain is proposed. The simulation of a high-fidelity ultra-wideband printed tapered monopole antenna(PTMA) gain and the compensation technology in the application of an ultra-wideband planar monopoly antenna fidelity with 5% improvement has verified the compensation technique, which is valuable to the design of high-fidelity ultra-wideband pulse antennas.