The invention discloses a wide-beam circularly-polarized phased-array antenna unit, and relates to the field of communication, measurement and control. The antenna unit comprises a dielectric plate and a feed inserting sheet; a radiation patch is applied on one surface of the dielectric plate and a microstrip line is carved in the same surface of the dielectric plate; the other surface of the dielectric plate is an antenna floor; and the radiation patch is a semicircular patch with a semicircular nick. According to the demands of communication, measurement and control on the polarization features and the installation space, the wide-beam circularly-polarized phased-array antenna unit is designed into the circularly-polarized radiation unit structure with wide standing wave bandwidth, wide axis ratio bandwidth, and wide beam width; and the wide-beam circularly-polarized phased-array antenna unit further has the characteristics of small size, easy integration, capability of realizing brick type phased-array antenna design and the like, so that the antenna unit is suitable for manufacturing the high-performance low-outline circularly-polarized antennas for aircraft carriers in the communication, measurement and control systems.