Abstract: A circularly polarized microstrip phased array antenna that can achieve azimuth±40 ° beam scanning in the 5G frequency band is proposed. The phased array antenna element is composed of a rectangular patch, upper and lower dielectric plates, a slot coupled feed structure and a metal reflective plate. The feed form of phased array antenna is realized by using the one-eighth unequal power divider of Chebyshev synthesis method. The test results show that the standing wave ratio bandwidth of the array antenna is 3. 25 GHz~ 3. 69 GHz, the port isolation is greater than 25 dB, the maximum gain during scanning is 21 dB, the gain fading is less than 3 dB, and the axial ratio at the maximum scanning angle is 2. 89 dB. The antenna has the advantages of low profile, high isolation, high gain and good beam scanning performance.