Abstract: In this paper, a directional dual-circularly polarized antenna with the characteristic of broadband is designed. The designed antenna has a three-layer structure: radiation layer, reflection layer and decoupling layer. The radiation layer is a rectangular driving patch to generate circularly polarized radiation by exciting the U-shaped gap. The antenna can realize left-handed circular polarization and right-handed circular polarization through two symmetrical microstrip feed ports respectively. The reflection layer is a metal plate placed directly below the antenna to achieve directional radiation pattern, but with the deterioration of antenna axis ratio and port isolation performance. To solve this problem, chamfering and slotting are made at the U-shaped gap of the radiation layer to improve the axial ratio bandwidth, and the decoupling layer of parasitic patch with etching period distribntion is loaded above the radiation layer to improve the port isolation. The designed antenna is fabricated and tested, the simulated and measured results show that the impedance bandwidth is from 1. 59 GHz to 7. 79 GHz ( 132. 1%) , the 3 dB axial ratio bandwidth is from 2. 75 GHz to 5. 78 GHz (71%), the port isolation of the antenna is less than -10 dB in the whole frequency band, and the peak gain is 8. 1 dBi.