Abstract: Aiming at the current shortcomings of ultra-wideband (UWB) microstrip monopole antennas such as narrow bandwidth and large size, a miniaturized ultra-wideband stepped microstrip monopole antenna is designed. The good UWB characteristic is obtained by using rectangular radiation patch slots, a stepped microstrip feeder and defective ground structure (DGS). The antenna return loss, voltage standing wave ratio (VSWR), radiation pattern and gain were simulated and optimized. The measured results show that the operating frequency range of antenna is 2.6−22.1 GHz, and the maximum gain is 12.9 dBi. The simulation and measurement results basically match. The antenna has simple structure, wide coverage frequency, compact size and good radiation characteristics in the operating frequency band, indicating that it is suitable for various UWB communication systems.