Embodiments of the present invention provide a beam forming network, including: a first 180-degree bridge for equal-power division, a 180-degree bridge for unequal-power division, a 90-degree phase shifter, and a second 180-degree bridge for equal-power division. A coupling port of a sum input port of the first 180-degree bridge for equal-power division is connected to a difference input port of the 180-degree bridge for unequal-power division, a straight-through port of the sum input port of the first 180-degree bridge for equal-power division is connected to an input port of the 90-degree phase shifter, an output port of the 90-degree phase shifter is connected to a difference input port of the second 180-degree bridge for equal-power division, and a straight-through port of a sum input port of the 180-degree bridge for unequal-power division is connected to a sum input port of the second 180-degree bridge for equal-power division.