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.