Abstract: This paper presents a design of a wideband and high gain circularly polarized(CP) antenna for millimeter-wave applications. The proposed lens consists of a hemispherical lens and a cylindrical polarizer, which integrate a dielectric polarizer with a dielectric hemispherical lens, and can transfer an incident wave from linear to circular polarization. The proposed CP lens is different from the cascaded design of a polarizer and a lens. It can achieve dual function by using single device. Moreover, it can decrease the profile of the extended hemispherical lens, and decrease the insertion loss and the cost of the antenna as well. Besides, benefiting from the low-cost three-dimensional (3D) printed technology, the CP lens can be fabricated in an accurate and convenient way. For demonstration, the proposed circularly polarized lens antenna is implemented and measured. This antenna can achieve a wide impedance bandwidth of 38% and a wide axial ratio(AR) bandwidth of 36%, and its gain can reach 22 dBic.