An antenna array and a communications device are provided. The antenna array includes a feeding waveguide and a waveguide cover. A waveguide port is disposed on the feeding waveguide, and an array of radiation slots are arranged along the length of the waveguide cover. The slots are configured to transmit signals fed from the waveguide port, and are classified into a first subarray and a second subarray. At a center frequency of the antenna array, the difference between a beam angle of the first subarray and a required beam angle, and a difference between a beam angle of the second subarray and the required beam angle, is each less than a specified threshold. With a frequency change of the antenna array, the beam angle of the first subarray and the beam angle of the second subarray change in opposing directions. Therefore, when the first and second subarray beams are combined, the combined beam angle has reduced frequency dependence.