In this paper, a 360° continuously scanning circular array antenna is presented. The circular array consists of eight Yagi-Uda monopoles, each one consisting of a driver, a reflector and four directors. When the circular array is fed identically, an azimuthal omnidirectional pattern is obtained. When the circular array is fed with an optimized distribution of excitations that is calculated by the expanded method of maximum power transmission efficiency, an azimuthal directional pattern with maximum directional gain is obtained. The measurement and simulation results indicate that the average gain of the omnidirectional pattern is about 3.78 dBi with azimuthal fluctuation of less than 2.0 dBi, and the maximum gain of the directional pattern is about 11.1 dBi with azimuthal continuously scanning fluctuation of less than 0.4 dBi and front-to-back ratio of larger than 12.5 dB. The reported circular array antenna is featured by high directional gain and 360° azimuthal beam continuous scanning, and it has potential applications in indoor communications.