A circular patch antenna with annular coupling is proposed in this paper. Using the circular metal patch as the radiation patch of the antenna, two new resonant bands are generated by introducing two resonant rings onto the dielectric plate. By adjusting the height between the circular patch and the coupling ring, the operating frequency band of the antenna is further broadened. The irregular dielectric substrate is processed by 3D printing technology, which effectually solves the problems of difficult processing and long production cycle of traditional processing methods. The measured results show that the return loss is less than -10 dB in the operating frequency band of 3.8~5.8 GHz. At 5.1 GHz, the antenna gain reaches 8.4 dBi. The relative bandwidth of the antenna is 42%, and it has good omnidirectional radiation characteristics. The measured results are in good consistent with the simulation ones.