A multi-band base station antenna comprises: a reflector; a plurality of high-band radiators arranged on the reflector; and a plurality of low-band radiators arranged on the reflector. Each of the plurality of low-band radiators comprises: a radiation substrate; a first dipole radiator including a first+dipole arm and a first−dipole arm formed on the radiation substrate; a second dipole radiator including a second+dipole arm and a second−dipole arm formed on the radiation substrate; and a metal coupler coupled to the lower portion of the radiation substrate. The metal coupler comprises: a first coupling patch located below the first+dipole arm; a second coupling patch located below the first−dipole arm; a third coupling patch located below the second+dipole arm; and a fourth coupling patch located below the second−dipole arm.