This application discloses an antenna, an antenna array, and a communications device. The antenna includes a radiation part and a feeding part. The feeding part is coupled to the radiation part and is configured to feed power to the radiation part, so that the radiation part radiates a low-frequency signal outward. The radiation part includes one or more frequency selection units with a bandpass characteristic, and the radiation part is a structure that is capable of exciting, when a high-frequency signal passes through, coupling currents. When the high-frequency signal passes through the radiation part, each pair of coupling currents excited on the radiation part appear in pairs and can cancel each other. This can reduce or even completely eliminate a high-frequency induced current with the same frequency as the high-frequency signal on the radiation part.